Ground is ground. Common usage is imprecise and dangerous.

The power return wires are not ground, neither is the reference voltage network
unless it is connected to the earth somehow.

Donald.
--
*Plain Text* email -- it's an accessibility issue
()  no proprietary attachments; no html mail
/\  ascii ribbon campaign - <www.asciiribbon.org>

----- Original Message -----
> From: "David" <dalbamonte@...>
> To: "Electronics 101" <Electronics_101@yahoogroups.com>
> Sent: Wednesday, February 29, 2012 10:13:32 PM
> Subject: [Electronics_101] When is ground ground?
> I have never been able to get my head around floating ground. I know
> it is ground relative to a signal, but how does that affect safety?
>
> I have three pieces of equipment I want to hook together.
>
> One is a late 50'/early 60's Hammond Organ. I know the chassis is
> floating ground because it is 2 wire mains.
>
> The second is a behringer mixer which has a three pin cord for the
> wall and a weird connecter on the mixer itself. I assumed that signal
> ground on this would be earth ground.
>
> The third is a keyboard which runs off a wall wart. I dont know
> exactly why I am not concerned about the ground on this, but I am not.
> I guess in reality I am not worried about it being compatible with the
> mixer.
>
> The hammond has a rca in. I want to come out of the mixer effects out
> and into the rca in. This will let me run my wall wart keyboard
> through the leslie. I know the pin on the leslie is connected to a
> capacitor which should isolate it from the dc operating voltage in the
> tube amp on the Hammond. I also know that if the capacitor is bad it
> will mess with the operating voltage on the Hammond and possibly not
> be as loud. So i want to test the dc voltage on the pin on the rca.
> But I am not comfortable about how the grounds would work so I checked
> with a volt meter. I figured the Bheringer would ground the Hammond
> through the ground on the signal cable if the difference was not too
> great. I measured the voltage between the ground on the Behringer and
> the Hammond. I was checking DC voltage and it was all over the place,
> but seemed to be less than 150mV. Then I checked the ac voltage.
> Between the behringer and the Hammond there was close to 18V AC. But
> when I disconnected the hammond the ac was still high. I put the lead
> on a screw on the switch plate (assumed ground) and got 26 V AC. Now I
> am really puzzled.
>
> When is ground, ground? And how can I be sure I can hook these things
> up without frying something?
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>

A "floating" chassis can pick up voltage, due to capacitive coupling effects. 
Think of a hot wire (120Vac), brought near to the chassis.  Stray capacitive
effects will couple from the wire to the chassis.  What is worse is when a
"ground" wire picks up voltage, due to current on it.  Due to the resistance
(and inductance) a wire can pick up a voltage across the wire itself.  Let's
pretend for a moment that one piece of equipment outputs a signal, and that
signal goes into say an amplifier.  The amplifier has a relatively low input
impedance, so there is some current on the wires.  The low side of that wire
won't be 0V across its length.  Had it been 0V at the output equipment,
relative to its ground, it would be some other voltage at the other equipment,
even if there was no difference between the chassis!

Now, let's pretend that these two pieces of equipment were on different circuit
breakers in your house.  Although that safety ground wire, going from the
chassis to the electrical box, should have zero current on it--and thus, making
that equipment chassis the same potential, it turns out that the ground wires
(and especially the neutral wires) are not zero volts, relative to one
another.  Too much coupling in equipment, due to stray capacitance.  The GND
wires should be "close" but the neutral wire's won't be.


Probably the best thing one can do is use isolation transformers on audio
equipment, along with shielded cable.  The transformer allows DC (and low
frequency, like 60Hz) differences, and hopefully reduces the possiblity of
ground loops.

In my head, "ground" refers to one of two things: the earth outside my house,
and a voltage node that is reasonably close to zero volts.  Once a signal
travels a TBD distance, "grounds" stop being the same potential--unless if they
happen to be by design or by chance.

 
Shawn Upton, KB1CKT
NAQCC 4723


________________________________
  From: David <dalbamonte@...>
To: Electronics_101@yahoogroups.com
Sent: Wednesday, February 29, 2012 10:13 PM
Subject: [Electronics_101] When is ground ground?


 
I have never been able to get my head around floating ground.  I know it is
ground relative to a signal, but how does that affect safety?

I have three pieces of equipment I want to hook together.

One is a late 50'/early 60's Hammond Organ.  I know the chassis is floating
ground because it is 2 wire mains.

The second is a behringer mixer which has a three pin cord for the wall and a
weird connecter on the mixer itself.  I assumed that signal ground on this would
be earth ground.

The third is a keyboard which runs off a wall wart.  I dont know exactly why I
am not concerned about the ground on this, but I am not.  I guess in reality I
am not worried about it being compatible with the mixer.

The hammond has a rca in.  I want to come out of the mixer effects out and into
the rca in.  This will let me run my wall wart keyboard through the leslie.  I
know the pin on the leslie is connected to a capacitor which should isolate it
from the dc operating voltage in the tube amp on the Hammond.  I also know that
if the capacitor is bad it will mess with the operating voltage on the Hammond
and possibly not be as loud.  So i want to test the dc voltage on the pin on the
rca.  But I am not comfortable about how the grounds would work so I checked
with a volt meter.   I figured the Bheringer would ground the Hammond through
the ground on the signal cable if the difference was not too great.  I measured
the voltage between the ground on the Behringer and the Hammond.  I was checking
DC voltage and it was all over the place, but seemed to be less than 150mV. 
Then I checked the ac voltage.  Between the behringer and the Hammond there was
close to 18V AC.
  But when I disconnected the hammond the ac was still high.  I put the lead on a
screw on the switch plate (assumed ground) and got 26 V AC.  Now I am really
puzzled.

When is ground, ground?  And how can I be sure I can hook these things up
without frying something?




[Non-text portions of this message have been removed]

On Thu, 01 Mar 2012 06:48:13 -0000, you wrote:

>
>
>--- In Electronics_101@yahoogroups.com, "Dan Nicoson" <A6intruder@...> wrote:
>>
>> I was going to suggest checking with a local motor rewinding shop.  In the
>> past I have bought a couple hundred feet from a local shop.  It has the
>> correct insulation coating to wind nicely and survive in your application.
>> They simply sold it to me by the pound based on what they paid.
>>
>
>Some motor shops have a process for vacuum impregnating they windings with
epoxy.  When I had motors rewound, I would ask for this service.  Extra cost, of
course.  But the rewound motors lasted a lot longer...
>
>So, ask a motor shop what they use.
>
>Richard
>
>
>
>
or simply take it to a motor shop and have them do
the job for you. Probably cheaper and more dependable
in the long run.

Keith Bowers WB4LSJ- Thomasville, NC

Ground is a central point hopefully common to all gear in a system.  It could be
say 4000 V difference between what is ground 3 blocks away.

However, some equipment that has say plastic enclosures where one cannot come in
contact with any metal or electrical parts the ground for this piece of
equipment would have its own ground inside and not connected to other equipment
grounds.  TVs are one example.

Ground is a zero voltage point, but may be zero to that piece of gear and may be
at a different voltage to another piece of equipment ground.

We should not get into RF grounds here for they are much more complex, but for
safety equipment where the operators can come in contact with metal and possible
electrical voltages these metals are "gounded", that is connected with physical
metal or wires together so they will be at the same voltage, zero for reference.

We typically like to bring all these grounds to Earth ground, the actual dirt
around the equipment.

With your equipment that has either a 2 prong AC plug or wal-wart the chassis
are covered and not exposed.  However, when connecting them together there needs
to be a reference for the signals to work together, but this does not have to be
the safety ground of a chassis, but must have some sort of reference point.

I think you are trying to get a safety or common ground on your equipment. 
Often this will only be thru the interconnecting cables, but if want a safety
ground then the chassis's or power supply grounds would need to be connected.

Ground is a zero voltage point, but might be at different voltages for different
pieces of gear.  I've seen PCs get grounded to other equipment and the PC would
shut down.  Why, its ground did not like being grounded to Earth ground or other
equipment grounds.  This was in the design.

In most equipment ground is the zero voltage point all other voltages operate in
reference to so the gear can function, but these grounds might not be at other
equipment grounds; different voltage.  Again has to be in the design.

73, ron, n9ee/r


--- In Electronics_101@yahoogroups.com, "David" <dalbamonte@...> wrote:
>
> I have never been able to get my head around floating ground.  I know it is
ground relative to a signal, but how does that affect safety?
>
> I have three pieces of equipment I want to hook together.
>
> One is a late 50'/early 60's Hammond Organ.  I know the chassis is floating
ground because it is 2 wire mains.
>
> The second is a behringer mixer which has a three pin cord for the wall and a
weird connecter on the mixer itself.  I assumed that signal ground on this would
be earth ground.
>
> The third is a keyboard which runs off a wall wart.  I dont know exactly why I
am not concerned about the ground on this, but I am not.  I guess in reality I
am not worried about it being compatible with the mixer.
>
> The hammond has a rca in.  I want to come out of the mixer effects out and
into the rca in.  This will let me run my wall wart keyboard through the leslie.
I know the pin on the leslie is connected to a capacitor which should isolate it
from the dc operating voltage in the tube amp on the Hammond.  I also know that
if the capacitor is bad it will mess with the operating voltage on the Hammond
and possibly not be as loud.  So i want to test the dc voltage on the pin on the
rca.  But I am not comfortable about how the grounds would work so I checked
with a volt meter.   I figured the Bheringer would ground the Hammond through
the ground on the signal cable if the difference was not too great.  I measured
the voltage between the ground on the Behringer and the Hammond.  I was checking
DC voltage and it was all over the place, but seemed to be less than 150mV. 
Then I checked the ac voltage.  Between the behringer and the Hammond there was
close to 18V AC.  But when I disconnected the hammond the ac was still high.  I
put the lead on a screw on the switch plate (assumed ground) and got 26 V AC. 
Now I am really puzzled.
>
> When is ground, ground?  And how can I be sure I can hook these things up
without frying something?
>

Unfortunately on many pieces of older equipment unless you have a detailed
schematic you will never know what the original designer intended for that
specific equipment. Many times racked pieces of equipment had extensive
circuitry connected and a point was chosen as a reference point for taking
readings from.  This ref. point many times was the chassis that the electronic
boards were mounted in. Often this point was never intended to be grounded as
what todays definition of grounded means.  Many times the chassis actually
carries current from parts of the circuit so it would not be a good idea to
ground this.  In fact making sure it is properly isolated would be more
important.  From an electrical point of view the most important part of the
circuit to have a ground connection is the power supply portion of the device. 
And a point to remember is to test handle this equipment chassis only when the
power is removed.  And if you must test this equipment use you ref. points not
ground unless that is what you intend.  Also all amplifier connection must be
secure and tight so as not to introduce any unwanted radio signals that can
enter on any open wiring.

Note: many times floating ground is really talking about this ref. point but not
always.  In many instances improperly connected power systems may be left
floating (i.e. no connection of the neutral line at the power source to ground)
and if you are taking a meter and trying to check a circuit to ground your
readings will not mean a thing.





-----Original Message-----
From: David <dalbamonte@...>
To: Electronics_101 <Electronics_101@yahoogroups.com>
Sent: Wed, Feb 29, 2012 9:13 pm
Subject: [Electronics_101] When is ground ground?





I have never been able to get my head around floating ground.  I know it is
ground relative to a signal, but how does that affect safety?

I have three pieces of equipment I want to hook together.

One is a late 50'/early 60's Hammond Organ.  I know the chassis is floating
ground because it is 2 wire mains.

The second is a behringer mixer which has a three pin cord for the wall and a
weird connecter on the mixer itself.  I assumed that signal ground on this would
be earth ground.

The third is a keyboard which runs off a wall wart.  I dont know exactly why I
am not concerned about the ground on this, but I am not.  I guess in reality I
am not worried about it being compatible with the mixer.

The hammond has a rca in.  I want to come out of the mixer effects out and into
the rca in.  This will let me run my wall wart keyboard through the leslie.  I
know the pin on the leslie is connected to a capacitor which should isolate it
from the dc operating voltage in the tube amp on the Hammond.  I also know that
if the capacitor is bad it will mess with the operating voltage on the Hammond
and possibly not be as loud.  So i want to test the dc voltage on the pin on the
rca.  But I am not comfortable about how the grounds would work so I checked
with a volt meter.   I figured the Bheringer would ground the Hammond through
the ground on the signal cable if the difference was not too great.  I measured
the voltage between the ground on the Behringer and the Hammond.  I was checking
DC voltage and it was all over the place, but seemed to be less than 150mV. 
Then I checked the ac voltage.  Between the behringer and the Hammond there was
close to 18V AC.  But when I disconnect ed the hammond the ac was still high.  I
put the lead on a screw on the switch plate (assumed ground) and got 26 V AC. 
Now I am really puzzled.

When is ground, ground?  And how can I be sure I can hook these things up
without frying something?









[Non-text portions of this message have been removed]

Thanks richard:

--- In Electronics_101@yahoogroups.com, "rtstofer" <rstofer@...> wrote:
>
> --- In Electronics_101@yahoogroups.com, "David" <dalbamonte@> wrote:
> > One is a late 50'/early 60's Hammond Organ.  I know the chassis is floating
ground because it is 2 wire mains.
> >
>
> There is a possibility that the chassis is grounded through the neutral.  This
was (and probably still is) a common scheme.  The manufacturer knows that the
neutral should be grounded (somewhere) and they know that the wide blade on the
outlet should be the neutral.  So, they connect it to the chassis.  They also
provide a polarized plug.
>

I'm not sure the Hammond came with a polarized plug and I am sure it has been
replaced at least once prior to when I got it.  I will check with the Hammond
gurus to see which wire gets connected to nuetral.


> Back in the bad old days people would sometimes change the plugs to a style
that wasn't polarized.  No problem as long as they didn't touch the metal.  But
just lose a knob and touch the metal shaft of a potentiometer while barefoot on
the garage floor and see what happens.  There's a reason I know this!
>
I know the metal column in my garage/studio/man cave is ground and my
telecaster/Champ is not.  Also learned the hard way.

David

That is what has me worried.

--- In Electronics_101@yahoogroups.com, Donald H Locker <dhlocker@...> wrote:
>
> Ground is ground. Common usage is imprecise and dangerous.
>
> The power return wires are not ground, neither is the reference voltage
network unless it is connected to the earth somehow.
>
> Donald.
> --

--- In Electronics_101@yahoogroups.com, Shawn Upton <kb1ckt@...> wrote:
>
[snip]  Thanks for the explanation.  just because I sniped it doesnt mean i did
not comprehend.

>>
> Probably the best thing one can do is use isolation transformers on audio
equipment, along with shielded cable.  The transformer allows DC (and low
frequency, like 60Hz) differences, and hopefully reduces the possiblity of
ground loops.
>
Are you talking isolation transformers on the input or on the power.  The Leslie
has isolation transformers which go between it an the organ.  That is why it is
easy to adapt the leslie to use a guitar amp as input.  The power isolation
transformers are pricy.  Anyone know of an inexpensive one?  In genereal I am
not getting a lot of hum.  In the mean time I am using a star configuration for
powering all my equipment.

> In my head, "ground" refers to one of two things: the earth outside my house,
and a voltage node that is reasonably close to zero volts.  Once a signal
travels a TBD distance, "grounds" stop being the same potential--unless if they
happen to be by design or by chance.
>
Does that mean I should not worry about the voltage measured between the two
devices?  26VAC seems excessive.

--- In Electronics_101@yahoogroups.com, "Ron Wright, N9EE" <mccrpt@...> wrote:
>
[snip]
>
> However, some equipment that has say plastic enclosures where one cannot come
in contact with any metal or electrical parts the ground for this piece of
equipment would have its own ground inside and not connected to other equipment
grounds.  TVs are one example.
>
The keyboard in my example is another.  That is one of the reasons I am not
worried about it.

> Ground is a zero voltage point, but may be zero to that piece of gear and may
be at a different voltage to another piece of equipment ground.
>
That is one of the things I am concened about.  In this case the connection of a
peice of tube gear to IC gear.  The tube stuff seems like it works by modulating
an applied high DC voltage.  The use capacitance coupling to keep one part of
the circuite from interfering with the voltage requirements of the nexts stage.

> We should not get into RF grounds here for they are much more complex, but for
safety equipment where the operators can come in contact with metal and possible
electrical voltages these metals are "gounded", that is connected with physical
metal or wires together so they will be at the same voltage, zero for reference.
>
> We typically like to bring all these grounds to Earth ground, the actual dirt
around the equipment.
>
> With your equipment that has either a 2 prong AC plug or wal-wart the chassis
are covered and not exposed.  However, when connecting them together there needs
to be a reference for the signals to work together, but this does not have to be
the safety ground of a chassis, but must have some sort of reference point.
>

> I think you are trying to get a safety or common ground on your equipment. 
Often this will only be thru the interconnecting cables, but if want a safety
ground then the chassis's or power supply grounds would need to be connected.
>
Yes.  I would like a safety ground.  When interconnecting multiple guitar amps
the practice used to be to disconnect the ground on the plug on all but one
amplifier.  Then the common ground is made by the shield on the interconnected
guitar cables.  I was thinking the mixer would be ground and then the cable
would provide ground.  I was stopped in step one when I found the shield on the
mixer to be 26V (18VAC to the hammond).  The hammond was plugged in but not
turned on during this test.

My plan was.  Fire up the mixer, test to ground on the hammond.  Then if I wasnt
too unhappy with the results, fire up the hammond and check again.  Then I was
going to check tip to tip for dc voltage.  I was stopped at step one.

> Ground is a zero voltage point, but might be at different voltages for
different pieces of gear.  I've seen PCs get grounded to other equipment and the
PC would shut down.  Why, its ground did not like being grounded to Earth ground
or other equipment grounds.  This was in the design.
>
> In most equipment ground is the zero voltage point all other voltages operate
in reference to so the gear can function, but these grounds might not be at
other equipment grounds; different voltage.  Again has to be in the design.
>

The hammond has an RCA input which I was hoping would provide the common ground,
but I do not know what the limitation are regarding the different ground point.

David

Besides checking voltage between two pieces of equipment, also check the
current.  It is possible for two pieces of unconnected and floating (with
respect to earth) equipment to many volts different, but have essentially no
leakage such that they can be safely connected together and to earth. If the
current between the two is less than a few milliamps, you should be safe. If
more, more research into why they so want to exchange charge is in order.

Donald.
--
*Plain Text* email -- it's an accessibility issue
()  no proprietary attachments; no html mail
/\  ascii ribbon campaign - <www.asciiribbon.org>

----- Original Message -----
> From: "David" <dalbamonte@...>
> To: "Electronics 101" <Electronics_101@yahoogroups.com>
> Sent: Thursday, March 1, 2012 1:23:23 PM
> Subject: [Electronics_101] Re: When is ground ground?
> --- In Electronics_101@yahoogroups.com, "Ron Wright, N9EE"
> <mccrpt@...> wrote:
> >
> [snip]
> >
> > However, some equipment that has say plastic enclosures where one
> > cannot come in contact with any metal or electrical parts the ground
> > for this piece of equipment would have its own ground inside and not
> > connected to other equipment grounds. TVs are one example.
> >
> The keyboard in my example is another. That is one of the reasons I am
> not worried about it.
>
> > Ground is a zero voltage point, but may be zero to that piece of
> > gear and may be at a different voltage to another piece of equipment
> > ground.
> >
> That is one of the things I am concened about. In this case the
> connection of a peice of tube gear to IC gear. The tube stuff seems
> like it works by modulating an applied high DC voltage. The use
> capacitance coupling to keep one part of the circuite from interfering
> with the voltage requirements of the nexts stage.
>
> > We should not get into RF grounds here for they are much more
> > complex, but for safety equipment where the operators can come in
> > contact with metal and possible electrical voltages these metals are
> > "gounded", that is connected with physical metal or wires together
> > so they will be at the same voltage, zero for reference.
> >
> > We typically like to bring all these grounds to Earth ground, the
> > actual dirt around the equipment.
> >
> > With your equipment that has either a 2 prong AC plug or wal-wart
> > the chassis are covered and not exposed. However, when connecting
> > them together there needs to be a reference for the signals to work
> > together, but this does not have to be the safety ground of a
> > chassis, but must have some sort of reference point.
> >
>
> > I think you are trying to get a safety or common ground on your
> > equipment. Often this will only be thru the interconnecting cables,
> > but if want a safety ground then the chassis's or power supply
> > grounds would need to be connected.
> >
> Yes. I would like a safety ground. When interconnecting multiple
> guitar amps the practice used to be to disconnect the ground on the
> plug on all but one amplifier. Then the common ground is made by the
> shield on the interconnected guitar cables. I was thinking the mixer
> would be ground and then the cable would provide ground. I was stopped
> in step one when I found the shield on the mixer to be 26V (18VAC to
> the hammond). The hammond was plugged in but not turned on during this
> test.
>
> My plan was. Fire up the mixer, test to ground on the hammond. Then if
> I wasnt too unhappy with the results, fire up the hammond and check
> again. Then I was going to check tip to tip for dc voltage. I was
> stopped at step one.
>
> > Ground is a zero voltage point, but might be at different voltages
> > for different pieces of gear. I've seen PCs get grounded to other
> > equipment and the PC would shut down. Why, its ground did not like
> > being grounded to Earth ground or other equipment grounds. This was
> > in the design.
> >
> > In most equipment ground is the zero voltage point all other
> > voltages operate in reference to so the gear can function, but these
> > grounds might not be at other equipment grounds; different voltage.
> > Again has to be in the design.
> >
>
> The hammond has an RCA input which I was hoping would provide the
> common ground, but I do not know what the limitation are regarding the
> different ground point.
>
> David
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>

What about the Washer?  If you tried to run it, would the wipers work?

I think I have figured out at least how the circuit is supposed to function. 
The key here is that the delay circuitry is moot when operating in either the
Low or High settings since Q3 will be fully on (saturated) from the pull-up R7. 
This energizes the relay and provides continuous power to one of the motor
windings.  When you are on the "low" setting, only one winding in the wiper
motor is energized and so it operates at a set speed.  When you are operating on
High, you are energizing two windings in the motor and so it runs faster.

When operating in the intermittent mode, Q2 is first turned on, which starts
pulling down the relay coil and also turns on Q3 which pulls the relay coil the
rest of the way down, switching power to the motor's low speed winding.  As the
wipers move through their arc, the motor position switch "Run" starts charging
C1 through R1.  Once the voltage gets high enough, Q1 starts turning on which
saps base drive from Q2.  Q2 eventually turns off, which then turns off Q3 which
in turn de-energizes the relay coil.  Since this time constant is less than the
total sweep time for the wipers, the wiper motor is still powered through its
"Run" switch.  (that is also why the wipers will complete the sweep when you
start the car if you shut it off with the wipers not in the parked position.) 
Once the wipers return to the park position, C1 holds the peak voltage it
charged to, which keeps Q1 turned on sucking all the base drive for Q2 keeping
it turned off.  However, C1 is no longer being charged by the "run" switch and
so it starts discharging through the Variable Resistor.  This POT is adjustable
at the steering column, probably on the wiper control lever, and is how you
select the delay between wiper sweeps.  Once C1 discharges enough, Q1 turns off,
which allows Q2 to turn on and start the process over again.

The way the washer works is when you press the button, you charge C2 through R8
which turns on Q2 and keeps it on after the button is released.  Q2 stays on
until C2 discharges through the parallel combo of R4 and the R5/Q2 base diode. 
This also bypasses the intermittent delay circuitry.

Since the only thing that is common to both the Intermittent and Low settings is
Q3, the relay, and the low speed motor winding, that is where I would look.  My
hunch is either too high of a Vce(sat) for Q3 which doesn't fully turn on the
relay, but you said that the relay clicks so that indicates the relay is at
least actuating.  That eliminates pretty much everything in your circuit shown,
all that is left are the relay contacts and the low speed winding on the motor. 
However, that all depends on what was the result from trying the Washer
function.  If the washer didn't work then my guess is either burnt contacts in
the relay, or a bad low speed winding on the motor.  The determining factor
would be when the wipers were on high, at what speed did they operate?  Normal? 
Slower?  If they operated slower, then you had burnt relay contacts.  If it
operated at normal speed then it was most likely a bad winding (or brushes) on
the motor and the Low speed winding wasn't able to initiate rotation.  When on
High, the high speed winding was able to give enough Umph to get the rotor
spinning and the low speed winding was able to start working from there. 
(Similar to the situation where you can tap a bad starter to get it spinning
again.)

Shawn

--- In Electronics_101@yahoogroups.com, Derek <derek@...> wrote:
>
> The "run" part is the wiper motor. There is a wiper on the motor such
> that when the wipers are not in park mode, 12V is being supplied;
> otherwise the connection is ground.
>
> INT switch is one of the states on the wiper switch. All switch
> conditions are open when the wipers are in the OFF control. On the
> steering column, the wiper control has 3 states. First state is
> INTermittent; this is is connected to +12V when active. When one
> switches to either LOW or HI speed, then the 12V is connected; the INT
> is switched open.
>
> When in the HI state, the LOW and INT are not of concern to the delay
> circuit since the motor is powered through a different connection, thus
> the reason the HI works and the LOW and INT did not. I have added
> another PDF file in the directory showing the shop electrical drawing
> portion. This should give better clarification of what is being
> connected and how.
>
> The pot below the INT switch is the wiper delay control and has a value
> from 500 to 10K Ohms.
>
> Derek Koonce
> DDK Interactive Consulting Services
>
>
>
> On 2/29/2012 3:21 PM, sstandfast wrote:
> >
> > In the upper right-hand corner of the hand drawn schematic, what is
> > that part labeled "run"? It's got an arc and one node is at +12V. I
> > don't recognize that symbol. Is that vehicle "ACC" power. I.E. only on
> > when the key is on?
> >
> > Also, can you confirm the state of switch "INT". By the intermittent
> > setting you mean the wipers only pulse once correct? Also can you
> > confirm that when the wipers are running normally in either low or
> > high speed the INT switch is open.
> >
> > Thanks,
> >
> > Shawn
> >
> > --- In Electronics_101@yahoogroups.com
> > <mailto:Electronics_101%40yahoogroups.com>, Derek <derek@> wrote:
> > >
> > > Donald,
> > >
> > > I have moved the schematic pdf into a sub directory in the Temp files
> > > section. The sub directory is "Wiper Sch problem". Here you will find
> > > the original pdf and a zip file of the LTSpice simulation.
> > >
> > > Sorry for the delay. Busy and did forget.
> > >
> > > Still waiting for someone to solve the original problem. I put in a txt
> > > file that outlines this as well.
> > >
> > > Derek Koonce
> > > DDK Interactive Consulting Services
> > >
> > >
> > >
> > > On 2/22/2012 6:01 PM, Donald H Locker wrote:
> > > >
> > > > One other question - is the .asc available separately? I'd hate to
> > > > have to re-enter the schematic, and the pdf rendering is pretty poor,
> > > > or maybe it's my colour-blindness. In any case, I can't really
> > read it.
> > > >
> > > > Donald.
> > > > --
> > > > *Plain Text* email -- it's an accessibility issue
> > > > () no proprietary attachments; no html mail
> > > > /\ ascii ribbon campaign - <www.asciiribbon.org>
> > > >
> > > > ----- Original Message -----
> > > > > From: "Derek" <derek@ <mailto:derek%40dkoonce.com>>
> > > > > To: "Electronics 101" <Electronics_101@yahoogroups.com
> > <mailto:Electronics_101%40yahoogroups.com>
> > > > <mailto:Electronics_101%40yahoogroups.com>>
> > > > > Sent: Wednesday, February 22, 2012 2:53:20 PM
> > > > > Subject: [Electronics_101] Another car circuit issue - wiper
> > problems
> > > > > OK, here is a good one for you thinkers out there. I just fixed my
> > > > > wiper
> > > > > delay circuit in my '88 Bronco II. There are no schematics on
> > how the
> > > > > circuit works, but I did reverse engineer it. There is only a couple
> > > > > of
> > > > > capacitors, some resistors, some diodes and 3 NPN transistors;
> > also a
> > > > > relay to handle the wiper motor power.
> > > > >
> > > > > The problem: Low and intermittent did not work. High wiper speed did
> > > > > work.
> > > > >
> > > > > The work: I checked all parts and found them to be functional:
> > > > > resistors
> > > > > has proper, or close enough values; capacitors were not shorted;
> > > > > diodes
> > > > > had proper Vf drops; NPN transistors show good diode readings
> > and even
> > > > > had decent h-fe values. The relay does click on and off. Oh,
> > there are
> > > > > no disconnected wires. The problem even manifested when I had the
> > > > > circuit hooked up on the bench and out of the car.
> > > > >
> > > > > Anyone want to fathom what the final fix was? I would be glad to
> > > > > answer
> > > > > any additional questions on this as well to see if anyone can get to
> > > > > the
> > > > > answer. I did post up my hand drawn schematic, a simulation
> > schematic,
> > > > > and picture of the bottom of the board. The file is in the Files
> > > > > section, Temp directory, and the file name is
> > > > > 'Wiper_sch_and_layout.pdf'.
> > > > >
> > > > > --
> > > > > Derek Koonce
> > > > > DDK Interactive Consulting Services
> > > > >
> > > > >
> > > > >
> > > > > ------------------------------------
> > > > >
> > > > > Please trim excess when replyingYahoo! Groups Links
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>

Shawn,

The low speed does not bypass this circuit, only the high. As for the
motor operation, it worked, through I swapped out due to the current
being around 2.8A instead of spec of 2.5 maximum.

You spent some time looking closely into this. And the problem was on
the board. But the solution was much simpler than a circuit issue.

My debugging process in the end led me to the solution.

Process:
1. Hook up 12V supply.
2. Connect 12V to LOW and heard relay go on. Relay turned off when 12V
removed.
3. Connect 12V to INT and heard relay go on. Relay had delay turn off
when 12V removed.
These first three steps basically confirmed the board is functional. But
outside the board was all good as well. External wiring is good.

More detail check.
4. Hook voltmeter on Motor output from board.
5. Connect 12V to LOW. Heard relay, but no 12V to motor output.
6. Probe board for 12V coming into relay contact. This is good.
7. Probe trace for 12V From relay to motor output. Not there.
8. Probe relay "pin" for 12V. This is GOOD!
Now, this last step is VERY close to solution.

Take VERY close look at joint. Using a microscope, there appeared to be
a ring in the solder joint. Hit joint with an iron and test.
WORKS!!

Now for the autopsy of WHY? Belief is that over the 24 years of this
car, there must have been some flux remaining on the board. During the
24 years, the flux eventually was able to eat a ring around the solder
joint and thus creating a disconnect.

So, moral of the story... if the electronics is decades old and there is
a connection problem, some reflow of solder joints may be all that is
required to fix. Check all solder joints VERY closely.

Derek Koonce
DDK Interactive Consulting Services



On 3/1/2012 11:13 AM, sstandfast wrote:
>
> What about the Washer? If you tried to run it, would the wipers work?
>
> I think I have figured out at least how the circuit is supposed to
> function. The key here is that the delay circuitry is moot when
> operating in either the Low or High settings since Q3 will be fully on
> (saturated) from the pull-up R7. This energizes the relay and provides
> continuous power to one of the motor windings. When you are on the
> "low" setting, only one winding in the wiper motor is energized and so
> it operates at a set speed. When you are operating on High, you are
> energizing two windings in the motor and so it runs faster.
>
> When operating in the intermittent mode, Q2 is first turned on, which
> starts pulling down the relay coil and also turns on Q3 which pulls
> the relay coil the rest of the way down, switching power to the
> motor's low speed winding. As the wipers move through their arc, the
> motor position switch "Run" starts charging C1 through R1. Once the
> voltage gets high enough, Q1 starts turning on which saps base drive
> from Q2. Q2 eventually turns off, which then turns off Q3 which in
> turn de-energizes the relay coil. Since this time constant is less
> than the total sweep time for the wipers, the wiper motor is still
> powered through its "Run" switch. (that is also why the wipers will
> complete the sweep when you start the car if you shut it off with the
> wipers not in the parked position.) Once the wipers return to the park
> position, C1 holds the peak voltage it charged to, which keeps Q1
> turned on sucking all the base drive for Q2 keeping it turned off.
> However, C1 is no longer being charged by the "run" switch and so it
> starts discharging through the Variable Resistor. This POT is
> adjustable at the steering column, probably on the wiper control
> lever, and is how you select the delay between wiper sweeps. Once C1
> discharges enough, Q1 turns off, which allows Q2 to turn on and start
> the process over again.
>
> The way the washer works is when you press the button, you charge C2
> through R8 which turns on Q2 and keeps it on after the button is
> released. Q2 stays on until C2 discharges through the parallel combo
> of R4 and the R5/Q2 base diode. This also bypasses the intermittent
> delay circuitry.
>
> Since the only thing that is common to both the Intermittent and Low
> settings is Q3, the relay, and the low speed motor winding, that is
> where I would look. My hunch is either too high of a Vce(sat) for Q3
> which doesn't fully turn on the relay, but you said that the relay
> clicks so that indicates the relay is at least actuating. That
> eliminates pretty much everything in your circuit shown, all that is
> left are the relay contacts and the low speed winding on the motor.
> However, that all depends on what was the result from trying the
> Washer function. If the washer didn't work then my guess is either
> burnt contacts in the relay, or a bad low speed winding on the motor.
> The determining factor would be when the wipers were on high, at what
> speed did they operate? Normal? Slower? If they operated slower, then
> you had burnt relay contacts. If it operated at normal speed then it
> was most likely a bad winding (or brushes) on the motor and the Low
> speed winding wasn't able to initiate rotation. When on High, the high
> speed winding was able to give enough Umph to get the rotor spinning
> and the low speed winding was able to start working from there.
> (Similar to the situation where you can tap a bad starter to get it
> spinning again.)
>
> Shawn
>
> --- In Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>, Derek <derek@...> wrote:
> >
> > The "run" part is the wiper motor. There is a wiper on the motor such
> > that when the wipers are not in park mode, 12V is being supplied;
> > otherwise the connection is ground.
> >
> > INT switch is one of the states on the wiper switch. All switch
> > conditions are open when the wipers are in the OFF control. On the
> > steering column, the wiper control has 3 states. First state is
> > INTermittent; this is is connected to +12V when active. When one
> > switches to either LOW or HI speed, then the 12V is connected; the INT
> > is switched open.
> >
> > When in the HI state, the LOW and INT are not of concern to the delay
> > circuit since the motor is powered through a different connection, thus
> > the reason the HI works and the LOW and INT did not. I have added
> > another PDF file in the directory showing the shop electrical drawing
> > portion. This should give better clarification of what is being
> > connected and how.
> >
> > The pot below the INT switch is the wiper delay control and has a value
> > from 500 to 10K Ohms.
> >
> > Derek Koonce
> > DDK Interactive Consulting Services
> >
> >
> >
> > On 2/29/2012 3:21 PM, sstandfast wrote:
> > >
> > > In the upper right-hand corner of the hand drawn schematic, what is
> > > that part labeled "run"? It's got an arc and one node is at +12V. I
> > > don't recognize that symbol. Is that vehicle "ACC" power. I.E.
> only on
> > > when the key is on?
> > >
> > > Also, can you confirm the state of switch "INT". By the intermittent
> > > setting you mean the wipers only pulse once correct? Also can you
> > > confirm that when the wipers are running normally in either low or
> > > high speed the INT switch is open.
> > >
> > > Thanks,
> > >
> > > Shawn
> > >
> > > --- In Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>
> > > <mailto:Electronics_101%40yahoogroups.com>, Derek <derek@> wrote:
> > > >
> > > > Donald,
> > > >
> > > > I have moved the schematic pdf into a sub directory in the Temp
> files
> > > > section. The sub directory is "Wiper Sch problem". Here you will
> find
> > > > the original pdf and a zip file of the LTSpice simulation.
> > > >
> > > > Sorry for the delay. Busy and did forget.
> > > >
> > > > Still waiting for someone to solve the original problem. I put
> in a txt
> > > > file that outlines this as well.
> > > >
> > > > Derek Koonce
> > > > DDK Interactive Consulting Services
> > > >
> > > >
> > > >
> > > > On 2/22/2012 6:01 PM, Donald H Locker wrote:
> > > > >
> > > > > One other question - is the .asc available separately? I'd hate to
> > > > > have to re-enter the schematic, and the pdf rendering is
> pretty poor,
> > > > > or maybe it's my colour-blindness. In any case, I can't really
> > > read it.
> > > > >
> > > > > Donald.
> > > > > --
> > > > > *Plain Text* email -- it's an accessibility issue
> > > > > () no proprietary attachments; no html mail
> > > > > /\ ascii ribbon campaign - <www.asciiribbon.org>
> > > > >
> > > > > ----- Original Message -----
> > > > > > From: "Derek" <derek@ <mailto:derek%40dkoonce.com>>
> > > > > > To: "Electronics 101" <Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>
> > > <mailto:Electronics_101%40yahoogroups.com>
> > > > > <mailto:Electronics_101%40yahoogroups.com>>
> > > > > > Sent: Wednesday, February 22, 2012 2:53:20 PM
> > > > > > Subject: [Electronics_101] Another car circuit issue - wiper
> > > problems
> > > > > > OK, here is a good one for you thinkers out there. I just
> fixed my
> > > > > > wiper
> > > > > > delay circuit in my '88 Bronco II. There are no schematics on
> > > how the
> > > > > > circuit works, but I did reverse engineer it. There is only
> a couple
> > > > > > of
> > > > > > capacitors, some resistors, some diodes and 3 NPN transistors;
> > > also a
> > > > > > relay to handle the wiper motor power.
> > > > > >
> > > > > > The problem: Low and intermittent did not work. High wiper
> speed did
> > > > > > work.
> > > > > >
> > > > > > The work: I checked all parts and found them to be functional:
> > > > > > resistors
> > > > > > has proper, or close enough values; capacitors were not shorted;
> > > > > > diodes
> > > > > > had proper Vf drops; NPN transistors show good diode readings
> > > and even
> > > > > > had decent h-fe values. The relay does click on and off. Oh,
> > > there are
> > > > > > no disconnected wires. The problem even manifested when I
> had the
> > > > > > circuit hooked up on the bench and out of the car.
> > > > > >
> > > > > > Anyone want to fathom what the final fix was? I would be glad to
> > > > > > answer
> > > > > > any additional questions on this as well to see if anyone
> can get to
> > > > > > the
> > > > > > answer. I did post up my hand drawn schematic, a simulation
> > > schematic,
> > > > > > and picture of the bottom of the board. The file is in the Files
> > > > > > section, Temp directory, and the file name is
> > > > > > 'Wiper_sch_and_layout.pdf'.
> > > > > >
> > > > > > --
> > > > > > Derek Koonce
> > > > > > DDK Interactive Consulting Services
> > > > > >
> > > > > >
> > > > > >
> > > > > > ------------------------------------
> > > > > >
> > > > > > Please trim excess when replyingYahoo! Groups Links
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>

On 2/29/2012 9:13 PM, David wrote:
>
> I have never been able to get my head around floating ground. I know
> it is ground relative to a signal, but how does that affect safety?
>
> I have three pieces of equipment I want to hook together.
>
> One is a late 50'/early 60's Hammond Organ. I know the chassis is
> floating ground because it is 2 wire mains.
>
> The second is a behringer mixer which has a three pin cord for the
> wall and a weird connecter on the mixer itself. I assumed that signal
> ground on this would be earth ground.
>
> The third is a keyboard which runs off a wall wart. I dont know
> exactly why I am not concerned about the ground on this, but I am not.
> I guess in reality I am not worried about it being compatible with the
> mixer.
>
> The hammond has a rca in. I want to come out of the mixer effects out
> and into the rca in. This will let me run my wall wart keyboard
> through the leslie. I know the pin on the leslie is connected to a
> capacitor which should isolate it from the dc operating voltage in the
> tube amp on the Hammond. I also know that if the capacitor is bad it
> will mess with the operating voltage on the Hammond and possibly not
> be as loud. So i want to test the dc voltage on the pin on the rca.
> But I am not comfortable about how the grounds would work so I checked
> with a volt meter. I figured the Bheringer would ground the Hammond
> through the ground on the signal cable if the difference was not too
> great. I measured the voltage between the ground on the Behringer and
> the Hammond. I was checking DC voltage and it was all over the place,
> but seemed to be less than 150mV. Then I checked the ac voltage.
> Between the behringer and the Hammond there was close to 18V AC. But
> when I disconnected the hammond the ac was still high. I put the lead
> on a screw on the switch plate (assumed ground) and got 26 V AC. Now I
> am really puzzled.
>
> When is ground, ground? And how can I be sure I can hook these things
> up without frying something?
>
I can't add anything to what has been previously said about "What is
ground?".  However, you can make some easy checks with a volt meter's
ohm scale to see if it is safe to connect the organ and keyboard to the
mixer.   Measure the resistance between each pin on the Hammond Organ's
output connector and each pin on the AC power plug.  It should be
infinite.  Repeat the same test with input pins of the mixer and its AC
power plug.  Repeat the same test with the output pins of the keyboard
and its
AC power plug.

If all the readings are infinite than is is safe to connect the organ
and keyboard to the mixer.
If only the mixer shows a low resistance between its AC power plug's
ground pin and one or more of its input pins than it is safe to connect
the organ and keyboard to the mixer.

Howard.


[Non-text portions of this message have been removed]

From a lightning-protection standpoint, all ground rods need to be
connected together with a heavy conductor, and
all lines entering a structure would use an "SPE", single-point-entry;
these grounds would tie together to a bulkhead of some sort at that
point, as would the building ground, and maybe one or more ground rods
for the bulkhead itself. Typically, the electrical ground and neutral
wires are tied together at the breaker box, regardless, AFAIK. Whatever
"ground" the telco, cable TV, etc., are used would also tie to this
bulkhead, and the lines would also enter the building at that same
point. If you have a ground rod connected to Device A, and a different
ground rod connected to Device B, without the two ground rods being tied
together with a heavy conductor, there can be a very *large* difference
in potential between the two devices in the event of a lightning strike.

I am not familiar with audio equipment, but I seem to recall something
called a "Pin 1" problem with XLR connectors and "ground", IIRC.

FWIW, I have seen an instance where the neutral wire from the pole was
not exactly at "ground" potential, as measured by an electrician...

Randy

On 3/1/2012 9:08 AM, Ron Wright, N9EE wrote:
>
> Ground is a central point hopefully common to all gear in a system. It
> could be say 4000 V difference between what is ground 3 blocks away.
>
> However, some equipment that has say plastic enclosures where one
> cannot come in contact with any metal or electrical parts the ground
> for this piece of equipment would have its own ground inside and not
> connected to other equipment grounds. TVs are one example.
>
> Ground is a zero voltage point, but may be zero to that piece of gear
> and may be at a different voltage to another piece of equipment ground.
>
> We should not get into RF grounds here for they are much more complex,
> but for safety equipment where the operators can come in contact with
> metal and possible electrical voltages these metals are "gounded",
> that is connected with physical metal or wires together so they will
> be at the same voltage, zero for reference.
>
> We typically like to bring all these grounds to Earth ground, the
> actual dirt around the equipment.
>
> With your equipment that has either a 2 prong AC plug or wal-wart the
> chassis are covered and not exposed. However, when connecting them
> together there needs to be a reference for the signals to work
> together, but this does not have to be the safety ground of a chassis,
> but must have some sort of reference point.
>
> I think you are trying to get a safety or common ground on your
> equipment. Often this will only be thru the interconnecting cables,
> but if want a safety ground then the chassis's or power supply grounds
> would need to be connected.
>
> Ground is a zero voltage point, but might be at different voltages for
> different pieces of gear. I've seen PCs get grounded to other
> equipment and the PC would shut down. Why, its ground did not like
> being grounded to Earth ground or other equipment grounds. This was in
> the design.
>
> In most equipment ground is the zero voltage point all other voltages
> operate in reference to so the gear can function, but these grounds
> might not be at other equipment grounds; different voltage. Again has
> to be in the design.
>
> 73, ron, n9ee/r
>
> --- In Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>, "David" <dalbamonte@...>
> wrote:
> >
> > I have never been able to get my head around floating ground. I know
> it is ground relative to a signal, but how does that affect safety?
> >
> > I have three pieces of equipment I want to hook together.
> >
> > One is a late 50'/early 60's Hammond Organ. I know the chassis is
> floating ground because it is 2 wire mains.
> >
> > The second is a behringer mixer which has a three pin cord for the
> wall and a weird connecter on the mixer itself. I assumed that signal
> ground on this would be earth ground.
> >
> > The third is a keyboard which runs off a wall wart. I dont know
> exactly why I am not concerned about the ground on this, but I am not.
> I guess in reality I am not worried about it being compatible with the
> mixer.
> >
> > The hammond has a rca in. I want to come out of the mixer effects
> out and into the rca in. This will let me run my wall wart keyboard
> through the leslie. I know the pin on the leslie is connected to a
> capacitor which should isolate it from the dc operating voltage in the
> tube amp on the Hammond. I also know that if the capacitor is bad it
> will mess with the operating voltage on the Hammond and possibly not
> be as loud. So i want to test the dc voltage on the pin on the rca.
> But I am not comfortable about how the grounds would work so I checked
> with a volt meter. I figured the Bheringer would ground the Hammond
> through the ground on the signal cable if the difference was not too
> great. I measured the voltage between the ground on the Behringer and
> the Hammond. I was checking DC voltage and it was all over the place,
> but seemed to be less than 150mV. Then I checked the ac voltage.
> Between the behringer and the Hammond there was close to 18V AC. But
> when I disconnected the hammond the ac was still high. I put the lead
> on a screw on the switch plate (assumed ground) and got 26 V AC. Now I
> am really puzzled.
> >
> > When is ground, ground? And how can I be sure I can hook these
> things up without frying something?
> >
>
>
>
> No virus found in this message.
> Checked by AVG - www.avg.com <http://www.avg.com>
> Version: 2012.0.1913 / Virus Database: 2114/4842 - Release Date: 02/29/12
>



[Non-text portions of this message have been removed]

thus the use of isolation transformers



Nemo dat quod non habet


________________________________
  From: David <dalbamonte@...>
To: Electronics_101@yahoogroups.com
Sent: Thursday, March 1, 2012 9:31 AM
Subject: [Electronics_101] Re: When is ground ground?



 

That is what has me worried.

--- In Electronics_101@yahoogroups.com, Donald H Locker <dhlocker@...> wrote:
>
> Ground is ground. Common usage is imprecise and dangerous.
>
> The power return wires are not ground, neither is the reference voltage
network unless it is connected to the earth somehow.
>
> Donald.
> --




[Non-text portions of this message have been removed]

http://www.amazon.com/gp/product/B007BUPKAW/ref=pd_lpo_k2_dp_sr_2?pf_rd_p=486539\
851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=3540255826&pf_rd_m=ATVPDKIKX0DE\
R&pf_rd_r=0Z74FSZGMAYGJTZQ50TR
 
 
http://www.amazon.com/Crystal-Self-Powered-Radio-ebook/dp/B007F7VJK6/ref=sr_1_2?\
s=digital-text&ie=UTF8&qid=1330624133&sr=1-2

I placed these in the read for free Amazon Prime category. If you have never
built a crystal set you might want to. That was the first radio I built as a wee
lad and is fond memories. Micro Cogen has extensive info on the care and feeding
of lead acid batteries.
Enjoy!
Kirk



Nemo dat quod non habet

[Non-text portions of this message have been removed]

Bill and friends of Electronics_101,


> By the way Jong how is everything going in NYC?

My first official announcement... I am no longer in NYC.  Now I live in Hawaii
!!!

Yeah !!!!
=====

Shhhhh, don't tell anybody.  It is a  secret between just us electronics_101
guys.

:-)


Jong



--- On Tue, 2/28/12, b_p1969 <b_p1969@...> wrote:

> From: b_p1969 <b_p1969@...>
> Subject: [Electronics_101] LED lights for my cabin
> To: Electronics_101@yahoogroups.com
> Date: Tuesday, February 28, 2012, 2:54 PM
> Thanks for all the answers and web
> sites you guys gave me. I will try jongs suggestion and
> experiment with my first with johns 3 LEDs and 1 resistor
> suggestion. By the way Jong how is everything going in NYC?
> Bill
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>     Electronics_101-fullfeatured@yahoogroups.com
>
>

Derek,

Was the ring _around_ the solder joint, in the copper, or in the
solder itself close to the pin?

If the second, this fault is very common and has nothing to do with flux.

There are a number of factors that cause or contribute to this type of
solder joint failure:

A) Thermal cycles. They are absolutely essential.
B) No freedom of movement for component (mounting points, other solder
joints), so force is applied to the solder joint.
C) pin plating, some platings appear to be more prone to this than others.

I have managed to cause this fault in lab conditions in a relatively
short time (weeks) using hard thermal cycles (-20 to +40°C). It is
basically a mechanical stress failure. Solder cold flows under
pressure, if you flow it this way and that many times it will fatigue.
The failure is very distinct from say vibration or shock failures,
where the copper will rip off the pad.

Experience will teach where these cracks occur, a typical example are
components mounted to heatsinks. If the heatsink is also mounted
rigidly and the component gets hot it stresses the solder joint. In
severe cased just reflowing the joint will not remedy the situation
for long enough, then you need to take additional measures such as
S-bends or stranded wire connections.

ST


On Fri, Mar 2, 2012 at 12:43 AM, Derek <derek@...> wrote:
> Shawn,
>
> The low speed does not bypass this circuit, only the high. As for the
> motor operation, it worked, through I swapped out due to the current
> being around 2.8A instead of spec of 2.5 maximum.
>
> You spent some time looking closely into this. And the problem was on
> the board. But the solution was much simpler than a circuit issue.
>
> My debugging process in the end led me to the solution.
>
> Process:
> 1. Hook up 12V supply.
> 2. Connect 12V to LOW and heard relay go on. Relay turned off when 12V
> removed.
> 3. Connect 12V to INT and heard relay go on. Relay had delay turn off
> when 12V removed.
> These first three steps basically confirmed the board is functional. But
> outside the board was all good as well. External wiring is good.
>
> More detail check.
> 4. Hook voltmeter on Motor output from board.
> 5. Connect 12V to LOW. Heard relay, but no 12V to motor output.
> 6. Probe board for 12V coming into relay contact. This is good.
> 7. Probe trace for 12V From relay to motor output. Not there.
> 8. Probe relay "pin" for 12V. This is GOOD!
> Now, this last step is VERY close to solution.
>
> Take VERY close look at joint. Using a microscope, there appeared to be
> a ring in the solder joint. Hit joint with an iron and test.
> WORKS!!
>
> Now for the autopsy of WHY? Belief is that over the 24 years of this
> car, there must have been some flux remaining on the board. During the
> 24 years, the flux eventually was able to eat a ring around the solder
> joint and thus creating a disconnect.
>
> So, moral of the story... if the electronics is decades old and there is
> a connection problem, some reflow of solder joints may be all that is
> required to fix. Check all solder joints VERY closely.
>
> Derek Koonce
> DDK Interactive Consulting Services
>
>
>
> On 3/1/2012 11:13 AM, sstandfast wrote:
>>
>> What about the Washer? If you tried to run it, would the wipers work?
>>
>> I think I have figured out at least how the circuit is supposed to
>> function. The key here is that the delay circuitry is moot when
>> operating in either the Low or High settings since Q3 will be fully on
>> (saturated) from the pull-up R7. This energizes the relay and provides
>> continuous power to one of the motor windings. When you are on the
>> "low" setting, only one winding in the wiper motor is energized and so
>> it operates at a set speed. When you are operating on High, you are
>> energizing two windings in the motor and so it runs faster.
>>
>> When operating in the intermittent mode, Q2 is first turned on, which
>> starts pulling down the relay coil and also turns on Q3 which pulls
>> the relay coil the rest of the way down, switching power to the
>> motor's low speed winding. As the wipers move through their arc, the
>> motor position switch "Run" starts charging C1 through R1. Once the
>> voltage gets high enough, Q1 starts turning on which saps base drive
>> from Q2. Q2 eventually turns off, which then turns off Q3 which in
>> turn de-energizes the relay coil. Since this time constant is less
>> than the total sweep time for the wipers, the wiper motor is still
>> powered through its "Run" switch. (that is also why the wipers will
>> complete the sweep when you start the car if you shut it off with the
>> wipers not in the parked position.) Once the wipers return to the park
>> position, C1 holds the peak voltage it charged to, which keeps Q1
>> turned on sucking all the base drive for Q2 keeping it turned off.
>> However, C1 is no longer being charged by the "run" switch and so it
>> starts discharging through the Variable Resistor. This POT is
>> adjustable at the steering column, probably on the wiper control
>> lever, and is how you select the delay between wiper sweeps. Once C1
>> discharges enough, Q1 turns off, which allows Q2 to turn on and start
>> the process over again.
>>
>> The way the washer works is when you press the button, you charge C2
>> through R8 which turns on Q2 and keeps it on after the button is
>> released. Q2 stays on until C2 discharges through the parallel combo
>> of R4 and the R5/Q2 base diode. This also bypasses the intermittent
>> delay circuitry.
>>
>> Since the only thing that is common to both the Intermittent and Low
>> settings is Q3, the relay, and the low speed motor winding, that is
>> where I would look. My hunch is either too high of a Vce(sat) for Q3
>> which doesn't fully turn on the relay, but you said that the relay
>> clicks so that indicates the relay is at least actuating. That
>> eliminates pretty much everything in your circuit shown, all that is
>> left are the relay contacts and the low speed winding on the motor.
>> However, that all depends on what was the result from trying the
>> Washer function. If the washer didn't work then my guess is either
>> burnt contacts in the relay, or a bad low speed winding on the motor.
>> The determining factor would be when the wipers were on high, at what
>> speed did they operate? Normal? Slower? If they operated slower, then
>> you had burnt relay contacts. If it operated at normal speed then it
>> was most likely a bad winding (or brushes) on the motor and the Low
>> speed winding wasn't able to initiate rotation. When on High, the high
>> speed winding was able to give enough Umph to get the rotor spinning
>> and the low speed winding was able to start working from there.
>> (Similar to the situation where you can tap a bad starter to get it
>> spinning again.)
>>
>> Shawn
>>
>> --- In Electronics_101@yahoogroups.com
>> <mailto:Electronics_101%40yahoogroups.com>, Derek <derek@...> wrote:
>> >
>> > The "run" part is the wiper motor. There is a wiper on the motor such
>> > that when the wipers are not in park mode, 12V is being supplied;
>> > otherwise the connection is ground.
>> >
>> > INT switch is one of the states on the wiper switch. All switch
>> > conditions are open when the wipers are in the OFF control. On the
>> > steering column, the wiper control has 3 states. First state is
>> > INTermittent; this is is connected to +12V when active. When one
>> > switches to either LOW or HI speed, then the 12V is connected; the INT
>> > is switched open.
>> >
>> > When in the HI state, the LOW and INT are not of concern to the delay
>> > circuit since the motor is powered through a different connection, thus
>> > the reason the HI works and the LOW and INT did not. I have added
>> > another PDF file in the directory showing the shop electrical drawing
>> > portion. This should give better clarification of what is being
>> > connected and how.
>> >
>> > The pot below the INT switch is the wiper delay control and has a value
>> > from 500 to 10K Ohms.
>> >
>> > Derek Koonce
>> > DDK Interactive Consulting Services
>> >
>> >
>> >
>> > On 2/29/2012 3:21 PM, sstandfast wrote:
>> > >
>> > > In the upper right-hand corner of the hand drawn schematic, what is
>> > > that part labeled "run"? It's got an arc and one node is at +12V. I
>> > > don't recognize that symbol. Is that vehicle "ACC" power. I.E.
>> only on
>> > > when the key is on?
>> > >
>> > > Also, can you confirm the state of switch "INT". By the intermittent
>> > > setting you mean the wipers only pulse once correct? Also can you
>> > > confirm that when the wipers are running normally in either low or
>> > > high speed the INT switch is open.
>> > >
>> > > Thanks,
>> > >
>> > > Shawn
>> > >
>> > > --- In Electronics_101@yahoogroups.com
>> <mailto:Electronics_101%40yahoogroups.com>
>> > > <mailto:Electronics_101%40yahoogroups.com>, Derek <derek@> wrote:
>> > > >
>> > > > Donald,
>> > > >
>> > > > I have moved the schematic pdf into a sub directory in the Temp
>> files
>> > > > section. The sub directory is "Wiper Sch problem". Here you will
>> find
>> > > > the original pdf and a zip file of the LTSpice simulation.
>> > > >
>> > > > Sorry for the delay. Busy and did forget.
>> > > >
>> > > > Still waiting for someone to solve the original problem. I put
>> in a txt
>> > > > file that outlines this as well.
>> > > >
>> > > > Derek Koonce
>> > > > DDK Interactive Consulting Services
>> > > >
>> > > >
>> > > >
>> > > > On 2/22/2012 6:01 PM, Donald H Locker wrote:
>> > > > >
>> > > > > One other question - is the .asc available separately? I'd hate to
>> > > > > have to re-enter the schematic, and the pdf rendering is
>> pretty poor,
>> > > > > or maybe it's my colour-blindness. In any case, I can't really
>> > > read it.
>> > > > >
>> > > > > Donald.
>> > > > > --
>> > > > > *Plain Text* email -- it's an accessibility issue
>> > > > > () no proprietary attachments; no html mail
>> > > > > /\ ascii ribbon campaign - <www.asciiribbon.org>
>> > > > >
>> > > > > ----- Original Message -----
>> > > > > > From: "Derek" <derek@ <mailto:derek%40dkoonce.com>>
>> > > > > > To: "Electronics 101" <Electronics_101@yahoogroups.com
>> <mailto:Electronics_101%40yahoogroups.com>
>> > > <mailto:Electronics_101%40yahoogroups.com>
>> > > > > <mailto:Electronics_101%40yahoogroups.com>>
>> > > > > > Sent: Wednesday, February 22, 2012 2:53:20 PM
>> > > > > > Subject: [Electronics_101] Another car circuit issue - wiper
>> > > problems
>> > > > > > OK, here is a good one for you thinkers out there. I just
>> fixed my
>> > > > > > wiper
>> > > > > > delay circuit in my '88 Bronco II. There are no schematics on
>> > > how the
>> > > > > > circuit works, but I did reverse engineer it. There is only
>> a couple
>> > > > > > of
>> > > > > > capacitors, some resistors, some diodes and 3 NPN transistors;
>> > > also a
>> > > > > > relay to handle the wiper motor power.
>> > > > > >
>> > > > > > The problem: Low and intermittent did not work. High wiper
>> speed did
>> > > > > > work.
>> > > > > >
>> > > > > > The work: I checked all parts and found them to be functional:
>> > > > > > resistors
>> > > > > > has proper, or close enough values; capacitors were not shorted;
>> > > > > > diodes
>> > > > > > had proper Vf drops; NPN transistors show good diode readings
>> > > and even
>> > > > > > had decent h-fe values. The relay does click on and off. Oh,
>> > > there are
>> > > > > > no disconnected wires. The problem even manifested when I
>> had the
>> > > > > > circuit hooked up on the bench and out of the car.
>> > > > > >
>> > > > > > Anyone want to fathom what the final fix was? I would be glad to
>> > > > > > answer
>> > > > > > any additional questions on this as well to see if anyone
>> can get to
>> > > > > > the
>> > > > > > answer. I did post up my hand drawn schematic, a simulation
>> > > schematic,
>> > > > > > and picture of the bottom of the board. The file is in the Files
>> > > > > > section, Temp directory, and the file name is
>> > > > > > 'Wiper_sch_and_layout.pdf'.
>> > > > > >
>> > > > > > --
>> > > > > > Derek Koonce
>> > > > > > DDK Interactive Consulting Services
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > > ------------------------------------
>> > > > > >
>> > > > > > Please trim excess when replyingYahoo! Groups Links
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > >
>> > > > >
>> > > >
>> > >
>> > >
>> >
>>
>>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>

How did you accomplish that, Jong? Congrats.
More importantly, how can *I* accomplish the same thing?
Please advise.

Randy

On 3/1/2012 11:02 PM, jong kung wrote:
>
> Bill and friends of Electronics_101,
>
> > By the way Jong how is everything going in NYC?
>
> My first official announcement... I am no longer in NYC. Now I live in
> Hawaii !!!
>
> Yeah !!!!
> =====
>
> Shhhhh, don't tell anybody. It is a secret between just us
> electronics_101 guys.
>
> :-)
>
> Jong
>
> --- On Tue, 2/28/12, b_p1969 <b_p1969@...
> <mailto:b_p1969%40yahoo.com>> wrote:
>
> > From: b_p1969 <b_p1969@... <mailto:b_p1969%40yahoo.com>>
> > Subject: [Electronics_101] LED lights for my cabin
> > To: Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>
> > Date: Tuesday, February 28, 2012, 2:54 PM
> > Thanks for all the answers and web
> > sites you guys gave me. I will try jongs suggestion and
> > experiment with my first with johns 3 LEDs and 1 resistor
> > suggestion. By the way Jong how is everything going in NYC?
> > Bill
> >
> >
> >
> > ------------------------------------
> >
> > Please trim excess when replyingYahoo! Groups Links
> >
> >
> > Electronics_101-fullfeatured@yahoogroups.com
> <mailto:Electronics_101-fullfeatured%40yahoogroups.com>
> >
> >
>
>
>
> No virus found in this message.
> Checked by AVG - www.avg.com <http://www.avg.com>
> Version: 2012.0.1913 / Virus Database: 2114/4845 - Release Date: 03/01/12
>



[Non-text portions of this message have been removed]

Deportation perhaps? ;-)

On 2/03/2012 2:21 PM, Randy wrote:
> How did you accomplish that, Jong? Congrats.
> More importantly, how can *I* accomplish the same thing?
> Please advise.
>
> Randy
>
> On 3/1/2012 11:02 PM, jong kung wrote:
>> My first official announcement... I am no longer in NYC. Now I live
>> in Hawaii !!!

At 06:03 PM 2/26/2012, John Popelish wrote:

>On 02/26/2012 11:08 AM, lists wrote:
>
> > I don't think 53000 will be available anymore you're probably looking at
> > 68000uF (68MF) at 63V and it won't be cheap!
>
>  From Digikey, there is a 68,000uF 50V that you would have
>to solder leads on to the terminals (snap-in) for about $23,
>with a ripple current rating of about 14 amps.
>
>They have a screw terminal 68,000uf 63V 54A ripple current
>unit for about $75.  About 3" dia. X 4" high
>
>If I was buying this, I might buy 3 each, 20,000uF 50 or 63
>volt units and parallel them, for a cheap, high ripple
>current rating.


http://www.all-battery.com/browseproducts/Capacitor--56-000uf.html

56000 uF @ 50 volts. Only $24.95, am I missing something?
....
Oh, it's sold out but they haven't pulled that store listing. @@

Still looking.

Reese

Hawaii is still US so deportation wouldn't work. Maybe marry a weathly Widow in
need of tv repair and tech support.

--------

Willie Pierce
Direct TV sales/installations
Contact me for the best deal

Pls excuse any spelling errors sent from iPhone.
>
>


[Non-text portions of this message have been removed]

--- In Electronics_101@yahoogroups.com, Derek <derek@...> wrote:


> The low speed does not bypass this circuit, only the high.
Hmmm....Then the shop diagram you posted is wrong (the one from the service
manual that you posted second) because it shows that both the Lo and Hi switch
positions connect +12V to wire 993 (BLK/WT).  (As drawn it is the left switch on
the ganged switch.)

>
> Process:
> 1. Hook up 12V supply.
> 2. Connect 12V to LOW and heard relay go on. Relay turned off when 12V
> removed.
> 3. Connect 12V to INT and heard relay go on. Relay had delay turn off
> when 12V removed.
> These first three steps basically confirmed the board is functional. But
> outside the board was all good as well. External wiring is good.
>
> More detail check.
> 4. Hook voltmeter on Motor output from board.
> 5. Connect 12V to LOW. Heard relay, but no 12V to motor output.
> 6. Probe board for 12V coming into relay contact. This is good.
> 7. Probe trace for 12V From relay to motor output. Not there.
> 8. Probe relay "pin" for 12V. This is GOOD!
> Now, this last step is VERY close to solution.

So I was in the right vicinity at least!

>
> Take VERY close look at joint. Using a microscope, there appeared to be
> a ring in the solder joint. Hit joint with an iron and test.
> WORKS!!
>
> Now for the autopsy of WHY? Belief is that over the 24 years of this
> car, there must have been some flux remaining on the board. During the
> 24 years, the flux eventually was able to eat a ring around the solder
> joint and thus creating a disconnect.

I agree with Stefan, if the ring was in the solder joint and appeared to trace
the circumference of the pin, then it is more likely to be a stress fracture
than a corrosive flux problem.  I work for a High-Rel, Military and Aerospace
Engineering company and have seen this before.  We frequently have to ESS
(Environmental Stress Screen) production hardware as part of the acceptance test
prior to delivery.  This usually involves some combination of vibration testing
on a shaker table followed by several thermal cycles.  Some programs even
require testing in a Thermal/Vibe chamber that shakes the product as it cycles
through different temperatures.  The number one failure of hardware after ESS is
usually cracked solder joints.  We have worked very hard to improve our solder
process so that it is now a very rare failure but we take extra care, like
bonding or staking larger parts, designing stiffeners for the CCA's to minimize
PWB deflection, and providing strain relief where ever we can.  Really sensitive
components even get detached from the board and the pins soldered using jumper
wires instead of direct connection.

The point I am trying to make is that cracked solder joints is common.  If the
board is 20+ years old, it has seen lots of thermal cycles and so it is not
surprising that a solder joint failed.  Good job on tracking it down.  It was
definitely a head scratcher.

>
> So, moral of the story... if the electronics is decades old and there is
> a connection problem, some reflow of solder joints may be all that is
> required to fix. Check all solder joints VERY closely.

Very true!

Thanks for the puzzle.  I rarely get to play with hardware anymore, so getting
to put my Inspector Clusoe hat on again was fun.

Shawn

NOBODY gets deported to Hawaii !!! :(

Wharpt



-----Original Message-----
From: Ross McKenzie <valusoft@...>
To: Electronics_101 <Electronics_101@yahoogroups.com>
Sent: Fri, Mar 2, 2012 6:31 am
Subject: Re: Shhhhh !!!!.... Re: [Electronics_101] LED lights for my cabin




Deportation perhaps? ;-)

On 2/03/2012 2:21 PM, Randy wrote:
> How did you accomplish that, Jong? Congrats.
> More importantly, how can *I* accomplish the same thing?
> Please advise.
>
> Randy
>
> On 3/1/2012 11:02 PM, jong kung wrote:
>> My first official announcement... I am no longer in NYC. Now I live
>> in Hawaii !!!







[Non-text portions of this message have been removed]

> > NOBODY gets deported to Hawaii !!! :(

It is the same planet, even the same country.... but it is a completely
different world.


Jong



--- On Fri, 3/2/12, wharpt@... <wharpt@...> wrote:

> From: wharpt@... <wharpt@...>
> Subject: Re: Shhhhh !!!!.... Re: [Electronics_101] LED lights for my cabin
> To: Electronics_101@yahoogroups.com
> Date: Friday, March 2, 2012, 10:35 AM
>
> NOBODY gets deported to Hawaii !!! :(
>
> Wharpt
>
>
>
> -----Original Message-----
> From: Ross McKenzie <valusoft@...>
> To: Electronics_101 <Electronics_101@yahoogroups.com>
> Sent: Fri, Mar 2, 2012 6:31 am
> Subject: Re: Shhhhh !!!!.... Re: [Electronics_101] LED
> lights for my cabin
>
>
>
>
> Deportation perhaps? ;-)
>
> On 2/03/2012 2:21 PM, Randy wrote:
> > How did you accomplish that, Jong? Congrats.
> > More importantly, how can *I* accomplish the same
> thing?
> > Please advise.
> >
> > Randy
> >
> > On 3/1/2012 11:02 PM, jong kung wrote:
> >> My first official announcement... I am no longer in
> NYC. Now I live
> >> in Hawaii !!!
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>     Electronics_101-fullfeatured@yahoogroups.com
>
>

I've seen this exact problem multiple times on Honda heater-fan relays (~15
years old).  Went through almost the same troubleshooting hell you did the first
time (and a needlessly replaced blower motor).  Under a scope I could see a fine
crack all the way around one of the solder joints.  Remelt and fixed.  I blamed
it on heat-cycling stress, but who knows?

--- In Electronics_101@yahoogroups.com, Derek <derek@...> wrote:
>
> Shawn,
>
> The low speed does not bypass this circuit, only the high. As for the
> motor operation, it worked, through I swapped out due to the current
> being around 2.8A instead of spec of 2.5 maximum.
>
> You spent some time looking closely into this. And the problem was on
> the board. But the solution was much simpler than a circuit issue.
>
> My debugging process in the end led me to the solution.
>
> Process:
> 1. Hook up 12V supply.
> 2. Connect 12V to LOW and heard relay go on. Relay turned off when 12V
> removed.
> 3. Connect 12V to INT and heard relay go on. Relay had delay turn off
> when 12V removed.
> These first three steps basically confirmed the board is functional. But
> outside the board was all good as well. External wiring is good.
>
> More detail check.
> 4. Hook voltmeter on Motor output from board.
> 5. Connect 12V to LOW. Heard relay, but no 12V to motor output.
> 6. Probe board for 12V coming into relay contact. This is good.
> 7. Probe trace for 12V From relay to motor output. Not there.
> 8. Probe relay "pin" for 12V. This is GOOD!
> Now, this last step is VERY close to solution.
>
> Take VERY close look at joint. Using a microscope, there appeared to be
> a ring in the solder joint. Hit joint with an iron and test.
> WORKS!!
>
> Now for the autopsy of WHY? Belief is that over the 24 years of this
> car, there must have been some flux remaining on the board. During the
> 24 years, the flux eventually was able to eat a ring around the solder
> joint and thus creating a disconnect.
>
> So, moral of the story... if the electronics is decades old and there is
> a connection problem, some reflow of solder joints may be all that is
> required to fix. Check all solder joints VERY closely.
>
> Derek Koonce
> DDK Interactive Consulting Services
>

Randy (and all prospective future Hawaii locals),


> How did you accomplish that, Jong?

The hardest part is to really decide to move.  For me this was a no brainer
because I always wanted to move here (I lived here for 1 year in my younger
days).  I don't have children, so that itself makes the decision easier.

The second hardest part is the actual move.  That means I had to basically
donate or throw out MOST of what I owned.  Very painful - and very labor
intensive.  But I did ship my O-scope !!!  :-)

The third hardest part is staying.  I heard that many locals in Hawaii don't
invest in becoming friends with new arrivals (new arrivals = less than few
years).  People move here and eventually move back because of jobs, family back
home, tired of laid back attitude (can't get things done), etc..  Last time I
lived here, a local guy (good friend) told me to have family visit you IN
HAWAII, instead of constantly visiting them.  Everybody is happy (especially the
family who gets the Hawaii vacation) and it makes staying forever easier.

In the end.... it is just deciding that I had enough of NYC rat race and
deciding that I need to be back where I was the happiest. But "Hawaii" is many
different islands and each has their own local flavor.  I lived on Maui before
and I really LOVE Maui.  Now I moved to Oahu ("Honolulu island") it is almost
like NYC - except ... except everything !!  I mean everything.

I want to keep this channel clear - so.... private email me if you want to
"talk" about move to Hawaii...

:-)


Jong

Oh, I like it.  Thats what I need simple tests for simple folk. (In addition to
the good explanations previously received regarding ground.)

I do think you missed that I was going to connect the effects send out of the
mixer to the organ.  The output of the organ is to a speaker.  I think it is in
the 8 to 12 watts range.  There will be no effects return from this.  But I
understand what you are saying and thank you for it.

David

> I can't add anything to what has been previously said about "What is
> ground?".  However, you can make some easy checks with a volt meter's
> ohm scale to see if it is safe to connect the organ and keyboard to the
> mixer.   Measure the resistance between each pin on the Hammond Organ's
> output connector and each pin on the AC power plug.  It should be
> infinite.  Repeat the same test with input pins of the mixer and its AC
> power plug.  Repeat the same test with the output pins of the keyboard
> and its
> AC power plug.
>
> If all the readings are infinite than is is safe to connect the organ
> and keyboard to the mixer.
> If only the mixer shows a low resistance between its AC power plug's
> ground pin and one or more of its input pins than it is safe to connect
> the organ and keyboard to the mixer.
>
> Howard.
>
>
> [Non-text portions of this message have been removed]
>

You are the second to mention isolation transformers, but in context of my
example it is unclear if you are suggesting isloation of the input / output of
the indivual devices or isolation of the power supply.

--- In Electronics_101@yahoogroups.com, Kirk McLoren <kirkmcloren@...> wrote:
>
> thus the use of isolation transformers
>
> Nemo dat quod non habet
>
gratias multum amicus

This is a new question, about capacitors more generally.

One someday project I've been considering, making a capacitive discharge
battery tab welder. Assuming I assemble a bank of smaller caps in order
to get the larger capacitance value needed for this project, does it
matter whether (computer grade, expensive) polarized caps are used or can
I get away with (motor-start, inexpensive) non-polarized caps?

And since I've asked that, does it matter whether I use a polarized cap
in that welding machine application or not? It's on the output side of
the transformer, negative side of the rectifying diodes, and all it really
does is remove any remaining ac ripple from the dc output.

Or is there a size limitation for ac caps that makes dc caps the only
game in town for these sorts of larger values?

Reese