If your 12V DC motor doesn't draw too much power, I suggest you look at
buying a used "wall wart". I paid $3 for mine and use it to power the motor
which moves the table on my milling machine. For variable speed, I added a
variable 3 terminal regulator that cost less than $5. I'm not saying that
your thyristor power controller won't work, but it is probably more
dangerous than a wall wart. My key concern is what happens when the control
pot is bumped and the output goes to maximum.

Rick



-----Original Message-----
From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of oakite2000
Sent: Monday, February 18, 2013 10:38 AM
To: Electronics_101@yahoogroups.com
Subject: [Electronics_101] Thyristor Conroller

Hi,
I want to run a 12Volt D.C. motor from the mains power.
Has anyone got any idea what would happen if I connected the motor to my
half wave thyristor power controller,( which is designed for 240VAC
operation), and turned the output down to minimum?
If I connect my 240 VAC electric drill to the controller, it doesn't start
turning until I rotate the control pot. by about 30 degrees.
I don't want to try it without checking first, in case it burns out either
the controller, the motor, or both.
Thanks Guys
Jack



------------------------------------

Please trim excess when replyingYahoo! Groups Links

On 2/18/2013 6:56 AM, normnet2003 wrote:
>
> I recently purchased the following battery:
>
http://www.ebay.com/itm/6800mAh-DC-12V-Super-Rechargeable-Lithium-ion-Battery-En\
ergy-Storage-Pack-/230806115118?pt=US_Rechargeable_Batteries&hash=item35bd1dd32e
>
>
> I planed to use it to power a device requiring 12 volts at 4 amps for
> 10-20 minutes however their doesn't seem to be any power when I plug
> the 4 amp device to the battery as opposed to plugging it into the
> car's 12 power supply.
>
> I thought 6800 ma meant 6.8 amps for one hour?
> What lithium ion battery rating should I order for a 12 volt 4 amp
> 10-20 minute requirement?
>
> Norm
>
> __

I see the battery comes with a built in on-off switch. By any chance did
you forget to turn the battery on?

The other Howard


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

It will come to you not fully charged...charge it for 10 hours and give it
a try...
good advice howard.


On Mon, Feb 18, 2013 at 12:27 PM, Howard Hansen <hrhan@...> wrote:

> **
>
>
> On 2/18/2013 6:56 AM, normnet2003 wrote:
> >
> > I recently purchased the following battery:
> >
>
http://www.ebay.com/itm/6800mAh-DC-12V-Super-Rechargeable-Lithium-ion-Battery-En\
ergy-Storage-Pack-/230806115118?pt=US_Rechargeable_Batteries&hash=item35bd1dd32e
> >
> >
> > I planed to use it to power a device requiring 12 volts at 4 amps for
> > 10-20 minutes however their doesn't seem to be any power when I plug
> > the 4 amp device to the battery as opposed to plugging it into the
> > car's 12 power supply.
> >
> > I thought 6800 ma meant 6.8 amps for one hour?
> > What lithium ion battery rating should I order for a 12 volt 4 amp
> > 10-20 minute requirement?
> >
> > Norm
> >
> > __
>
> I see the battery comes with a built in on-off switch. By any chance did
> you forget to turn the battery on?
>
> The other Howard
>
> [Non-text portions of this message have been removed]
>
>
>


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

A battery rated for 6800 MAhr or 6.8 Ahr really means it will put out 680 mA
for 10 hours.  That is how they cheat.  In one hour, It may put out only 5.2
Amps for the hour.  Specsmanship!  Ain't it great!



Larry



From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of Howard Hansen
Sent: Monday, February 18, 2013 1:28 PM
To: Electronics_101@yahoogroups.com
Subject: Re: [Electronics_101] Lithium ion battery rating





On 2/18/2013 6:56 AM, normnet2003 wrote:
>
> I recently purchased the following battery:
>
http://www.ebay.com/itm/6800mAh-DC-12V-Super-Rechargeable-Lithium-ion-Batter
y-Energy-Storage-Pack-/230806115118?pt=US_Rechargeable_Batteries
<http://www.ebay.com/itm/6800mAh-DC-12V-Super-Rechargeable-Lithium-ion-Batte
ry-Energy-Storage-Pack-/230806115118?pt=US_Rechargeable_Batteries&hash=item3
5bd1dd32e> &hash=item35bd1dd32e
>
>
> I planed to use it to power a device requiring 12 volts at 4 amps for
> 10-20 minutes however their doesn't seem to be any power when I plug
> the 4 amp device to the battery as opposed to plugging it into the
> car's 12 power supply.
>
> I thought 6800 ma meant 6.8 amps for one hour?
> What lithium ion battery rating should I order for a 12 volt 4 amp
> 10-20 minute requirement?
>
> Norm
>
> __

I see the battery comes with a built in on-off switch. By any chance did
you forget to turn the battery on?

The other Howard

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





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

--- In Electronics_101@yahoogroups.com, "oakite2000" <stackerjack@...> wrote:
>
> Hi,
> I want to run a 12Volt D.C. motor from the mains power.
> Has anyone got any idea what would happen if I connected the motor to my half
wave thyristor power controller,( which is designed for 240VAC operation), and
turned the output down to minimum?
> If I connect my 240 VAC electric drill to the controller, it doesn't start
turning until I rotate the control pot. by about 30 degrees.
> I don't want to try it without checking first, in case it burns out either the
controller, the motor, or both.
> Thanks Guys
> Jack
>

Hi Jack,

In theory your idea should work. For instance, when I was 25 years, after my
graduation, I thought charging my 12V acid battery (60 AH) by using a power
triac, not thyristor, and a full diode bridge to let the charging current of the
two half-cycles equal. I measured on my DC ammeter about 15A. But soon later my
battery died. The reason is that the triac has to conduct during a relatively
very short phase (about 1ms, if I remember well but I will likely simulate the
idea in the near future on LTspice). During this period of time, a very high
triangular pulse (about 150A peak) stroke the battery cells... that couldn't cry
;)

In your case, the pulsing will be much lower for two reasons:
(1) The inductance of the motor windings
(2) The DC resistance of the motor is much higher than of a big battery.

I assume you will use a diode bridge to provide a varying DC voltage to supply
the motor and its thyristor controlling it. In general, it is not a good idea to
let the AC current unbalanced; like passing it during one half only. Anyway the
exact shape of the relatively high pulsed current depends on the motor power,
its speed and applied torque. But for the same DC current, I_dc (if 12V DC is
used), the heat generated inside the motor will be much higher. Assuming the
current pulse is square with amplitude I_max with a duty cycle K_dc and the
internal resistance is R_motor:

In case of DC:
P_dc = I_dc * I_dc * R_motor

In case of pulsing:
I_max = I_dc / K_dc
P_pls = I_max * I_max * R_motor * K_dc
P_pls = I_dc * I_dc * R_motor / K_dc

P_pls = P_dc / K_dc

So if the on phase is 1ms:
Full wave:
K_dc = 1ms/10ms = 1/10
P_pls = P_dc * 10

Half wave
K_dc = 1ms/20ms = 1/20 (if half wave)
P_pls = P_dc * 20

Hope this little helps.

Kerim

In article <kftotb+bb5q@eGroups.com>,
    oakite2000 <stackerjack@...> wrote:
> Hi, I want to run a 12Volt D.C. motor from the mains power. Has anyone
> got any idea what would happen if I connected the motor to my half wave
> thyristor power controller,( which is designed for 240VAC operation),
> and turned the output down to minimum?

Smoke, I expect.

--
Stuart Winsor

Only plain text for emails
http://www.asciiribbon.org

In article <006901ce0e02$5debeff0$19c3cfd0$@com>,
    Rick Sparber <rgsparber@...> wrote:
> If your 12V DC motor doesn't draw too much power, I suggest you look at
> buying a used "wall wart". I paid $3 for mine and use it to power the
> motor which moves the table on my milling machine.

If you're anything like me you have accumalateda large collection of the
things over the years!

Saw a lovely cartoon a while back.

--
Stuart Winsor

Only plain text for emails
http://www.asciiribbon.org

I'll try charging it again just in case.

Norm

--- In Electronics_101@yahoogroups.com, Frank Mead <wa6ujj@...> wrote:
>
> It will come to you not fully charged...charge it for 10 hours and give it
> a try...
> good advice howard.
>
>
> On Mon, Feb 18, 2013 at 12:27 PM, Howard Hansen <hrhan@...> wrote:
>
> > **
> >
> >
> > On 2/18/2013 6:56 AM, normnet2003 wrote:
> > >
> > > I recently purchased the following battery:
> > >
> >
http://www.ebay.com/itm/6800mAh-DC-12V-Super-Rechargeable-Lithium-ion-Battery-En\
ergy-Storage-Pack-/230806115118?pt=US_Rechargeable_Batteries&hash=item35bd1dd32e
> > >
> > >
> > > I planed to use it to power a device requiring 12 volts at 4 amps for
> > > 10-20 minutes however their doesn't seem to be any power when I plug
> > > the 4 amp device to the battery as opposed to plugging it into the
> > > car's 12 power supply.
> > >
> > > I thought 6800 ma meant 6.8 amps for one hour?
> > > What lithium ion battery rating should I order for a 12 volt 4 amp
> > > 10-20 minute requirement?
> > >
> > > Norm
> > >
> > > __
> >
> > I see the battery comes with a built in on-off switch. By any chance did
> > you forget to turn the battery on?
> >
> > The other Howard
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>

First of all it's a real shock hazard. The motor insulation probably isn't
designed to withstand 240VAC. There could be leakage to the case. If you DO
try it, please connect a safety ground wire to the motor case.

Second, not all thyristors are suitable for controlling motors. In
particular, triac-based incandescent "light dimmers" may not always turn
off between cycles of the AC line with inductive loads such as motors. The
result is that you could end up applying full AC line voltage to your motor.

Third, if you run the motor at the full rated torque you'll likely burn up
the motor due to I^2R heating. Let's say the motor delivers rated torque
when the shaft is spinning at 2/3 of the unloaded RPMs. That tells us that
the "back EMF" produced by the motor is 2/3 of the rated voltage, i.e. back
EMF = 8V = 2/3 of 12V. And let's say the current is 1A at full load.

Now, assuming that 12V _DC_ is supplied: The voltage drop through the
resistance of the windings and brushes is 12V - 8V = 4V. Thus, we can
determine the motor resistance is R=V/I=4V/1A=4 ohms. And the power
dissipated by the motor as heat is I^2R=1A^2*4 ohms=4W.

But what happens when the current is supplied in narrow pulses? Torque is
proportional to current. To get the same _average_ torque, you need a much
higher _peak_ torque - and corresponding peak current.

The pulses are approximately triangular (the edge of the sine wave). For
50Hz, I calculate the triangle width as .87 ms wide and 23 amps at its
peak. (You can verify that that gives an average current of 1A.)

The peak power is I^2R=(23A)^2*4ohms=2.13KW. The average power _during the
pulse_ (integrate the power) is 1/3 of that, 711W. But the duty cycle is
.87 ms/ 10ms so the overall average power dissipated in the motor is about
62W. Considering our hypothetical motor was designed to dissipate 4W, smoke
seems likely.

Bottom line, running a 12V motor with a thyristor controller from a 240V
line does not seem like a good idea. Likely to be harmful to the motor, the
controller - and you! :-)



On Mon, Feb 18, 2013 at 10:37 AM, oakite2000 <stackerjack@...>wrote:

> Hi,
> I want to run a 12Volt D.C. motor from the mains power.
> Has anyone got any idea what would happen if I connected the motor to my
> half wave thyristor power controller,( which is designed for 240VAC
> operation), and turned the output down to minimum?
> If I connect my 240 VAC electric drill to the controller, it doesn't start
> turning until I rotate the control pot. by about 30 degrees.
> I don't want to try it without checking first, in case it burns out either
> the controller, the motor, or both.
> Thanks Guys
> Jack
>


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

It works!! Thank you, thank you so much!!

Brenda

On 17/2/2013 12:50 PM, Howard Hansen wrote:
>
> Hello Brenda,
>
> You can not use the composite video cables going from the outputs of the
> DVD and VCR to the TV for recording a TV program on the DVD. Instead
> what you need to do is get another composite video cable. Connect this
> cable to the Sat Receiver composite video output jacks and the DVD
> composite video input jacks. Double check the installation of this
> cable to make sure it is connected to Sat receiver composite video
> output jacks and DVD composite video input jacks.
>
> The other Howard
>


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

Pray tell please describe the cartoon if you can't find a link to it...

Dave

-=-=-=-

On 18 February 2013, at 2:24 PM, lists wrote:

> Saw a lovely cartoon a while back.
>
> Stuart Winsor



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

I don't think discharging at close to the one hour rate to be a good idea.
If there is a temperature sensor in the battery pack (there should be!) it
will probably open the circuit quite quickly, even before you feel the
temperature rise outside of the casing.....but maybe 5 minutes later......

The supplier should be in a position to tell you what the maximum discharge
current could be, but don't be surprised if it's only 680ma......

Also, new batteries might need to be charged/discharged several times before
full capacity is reached....depending upon chemistry and manufacturer....

Remember, the 6800ma is the quoted capacity, not the discharge
rate.....major difference.....

Regards

Andy

I have a Max 197 AD connected as follows:

Source - 47KOhm - + - MAX197
                   |
                 zener
                   |
                 ground

With the source disconnected, the Max 197 reads about .22V.

With it connected to a voltage source, it reads about what I expect (3.38V
@ 12V source).

Why would the MAX197 read a voltage with no voltage input?  The other pins
read 0.0 when disconnected; only the two connected to the zener show this
weird voltage.

What is the purpose of the zener on the ground leg? Is it to raise the
level of conversion? Sounds to me to be an application issue somehow
with the IC trying to read a negative input voltage - 0V instead of the
zener-level as the '0'.

Derek Koonce
DDK Interactive Consulting Services


On 2/19/2013 9:04 AM, Yan Seiner wrote:
>
> I have a Max 197 AD connected as follows:
>
> Source - 47KOhm - + - MAX197
> |
> zener
> |
> ground
>
> With the source disconnected, the Max 197 reads about .22V.
>
> With it connected to a voltage source, it reads about what I expect (3.38V
> @ 12V source).
>
> Why would the MAX197 read a voltage with no voltage input? The other pins
> read 0.0 when disconnected; only the two connected to the zener show this
> weird voltage.
>
>



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

On Tue, February 19, 2013 10:50 am, Derek wrote:
> What is the purpose of the zener on the ground leg? Is it to raise the
> level of conversion? Sounds to me to be an application issue somehow
> with the IC trying to read a negative input voltage - 0V instead of the
> zener-level as the '0'.

The ascii art didn't quite turn out; the zener is on the input leg between
the 47KOhm resistor and the chip (where the + sign in my diagram).  Its
purpose is to limit load dumps (this is in an automotive application so
voltages can spike to 70V).

Any spike over 5V gets dumped to ground.

>
> Derek Koonce
> DDK Interactive Consulting Services
>
>
> On 2/19/2013 9:04 AM, Yan Seiner wrote:
>>
>> I have a Max 197 AD connected as follows:
>>
>> Source - 47KOhm - + - MAX197
>> |
>> zener
>> |
>> ground
>>
>> With the source disconnected, the Max 197 reads about .22V.
>>
>> With it connected to a voltage source, it reads about what I expect
>> (3.38V
>> @ 12V source).
>>
>> Why would the MAX197 read a voltage with no voltage input? The other
>> pins
>> read 0.0 when disconnected; only the two connected to the zener show
>> this
>> weird voltage.
>>
>>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> !DSPAM:5123cb97114941804284693!
>


--

On Tue, February 19, 2013 11:04 am, Yan Seiner wrote:
>
> On Tue, February 19, 2013 10:50 am, Derek wrote:
>> What is the purpose of the zener on the ground leg? Is it to raise the
>> level of conversion? Sounds to me to be an application issue somehow
>> with the IC trying to read a negative input voltage - 0V instead of the
>> zener-level as the '0'.
>
> The ascii art didn't quite turn out; the zener is on the input leg between
> the 47KOhm resistor and the chip (where the + sign in my diagram).  Its
> purpose is to limit load dumps (this is in an automotive application so
> voltages can spike to 70V).

To clarify:  the zener is connected from the + sign to ground.

Source - 47KOhm - + - MAX197
.                 |
.               zener
.                 |
.               ground

Ahh, that makes sense. What you are seeing is a floating input voltage.
The zener has a high impedance to ground if not above the breakdown
voltage. Properly, you can add a 1MEG to ground, parallel to the zener
and that should set the input voltage to 0 and not affect the connected
reading to any major concern.

Derek Koonce
DDK Interactive Consulting Services


On 2/19/2013 11:04 AM, Yan Seiner wrote:
>
>
> On Tue, February 19, 2013 10:50 am, Derek wrote:
> > What is the purpose of the zener on the ground leg? Is it to raise the
> > level of conversion? Sounds to me to be an application issue somehow
> > with the IC trying to read a negative input voltage - 0V instead of the
> > zener-level as the '0'.
>
> The ascii art didn't quite turn out; the zener is on the input leg between
> the 47KOhm resistor and the chip (where the + sign in my diagram). Its
> purpose is to limit load dumps (this is in an automotive application so
> voltages can spike to 70V).
>
> Any spike over 5V gets dumped to ground.
>
> >
> > Derek Koonce
> > DDK Interactive Consulting Services
> >
> >
> > On 2/19/2013 9:04 AM, Yan Seiner wrote:
> >>
> >> I have a Max 197 AD connected as follows:
> >>
> >> Source - 47KOhm - + - MAX197
> >> |
> >> zener
> >> |
> >> ground
> >>
> >> With the source disconnected, the Max 197 reads about .22V.
> >>
> >> With it connected to a voltage source, it reads about what I expect
> >> (3.38V
> >> @ 12V source).
> >>
> >> Why would the MAX197 read a voltage with no voltage input? The other
> >> pins
> >> read 0.0 when disconnected; only the two connected to the zener show
> >> this
> >> weird voltage.
> >>
> >>
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > !DSPAM:5123cb97114941804284693!
> >
>
> --
>
>



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

OK, will do.

Thanks!

--Yan

On Tue, February 19, 2013 11:08 am, Derek wrote:
> Ahh, that makes sense. What you are seeing is a floating input voltage.
> The zener has a high impedance to ground if not above the breakdown
> voltage. Properly, you can add a 1MEG to ground, parallel to the zener
> and that should set the input voltage to 0 and not affect the connected
> reading to any major concern.
>
> Derek Koonce
> DDK Interactive Consulting Services
>
>
> On 2/19/2013 11:04 AM, Yan Seiner wrote:
>>
>>
>> On Tue, February 19, 2013 10:50 am, Derek wrote:
>> > What is the purpose of the zener on the ground leg? Is it to raise the
>> > level of conversion? Sounds to me to be an application issue somehow
>> > with the IC trying to read a negative input voltage - 0V instead of
>> the
>> > zener-level as the '0'.
>>
>> The ascii art didn't quite turn out; the zener is on the input leg
>> between
>> the 47KOhm resistor and the chip (where the + sign in my diagram). Its
>> purpose is to limit load dumps (this is in an automotive application so
>> voltages can spike to 70V).
>>
>> Any spike over 5V gets dumped to ground.
>>
>> >
>> > Derek Koonce
>> > DDK Interactive Consulting Services
>> >
>> >
>> > On 2/19/2013 9:04 AM, Yan Seiner wrote:
>> >>
>> >> I have a Max 197 AD connected as follows:
>> >>
>> >> Source - 47KOhm - + - MAX197
>> >> |
>> >> zener
>> >> |
>> >> ground
>> >>
>> >> With the source disconnected, the Max 197 reads about .22V.
>> >>
>> >> With it connected to a voltage source, it reads about what I expect
>> >> (3.38V
>> >> @ 12V source).
>> >>
>> >> Why would the MAX197 read a voltage with no voltage input? The other
>> >> pins
>> >> read 0.0 when disconnected; only the two connected to the zener show
>> >> this
>> >> weird voltage.
>> >>
>> >>
>> >
>> >
>> >
>> > [Non-text portions of this message have been removed]
>> >
>> >
>> >
>> >
>> >
>>
>> --
>>
>>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> !DSPAM:5123cf94126799633161998!
>


--

I usually got such weird (induced and rectified) voltages when a non linear
device is almost open circuited and if the testing wires are somehow long hence
acting as receiving antenna ;)

--- In Electronics_101@yahoogroups.com, "Yan Seiner" <yan@...> wrote:
>
> OK, will do.
>
> Thanks!
>
> --Yan
>
> On Tue, February 19, 2013 11:08 am, Derek wrote:
> > Ahh, that makes sense. What you are seeing is a floating input voltage.
> > The zener has a high impedance to ground if not above the breakdown
> > voltage. Properly, you can add a 1MEG to ground, parallel to the zener
> > and that should set the input voltage to 0 and not affect the connected
> > reading to any major concern.
> >
> > Derek Koonce
> > DDK Interactive Consulting Services
> >
> >
> > On 2/19/2013 11:04 AM, Yan Seiner wrote:
> >>
> >>
> >> On Tue, February 19, 2013 10:50 am, Derek wrote:
> >> > What is the purpose of the zener on the ground leg? Is it to raise the
> >> > level of conversion? Sounds to me to be an application issue somehow
> >> > with the IC trying to read a negative input voltage - 0V instead of
> >> the
> >> > zener-level as the '0'.
> >>
> >> The ascii art didn't quite turn out; the zener is on the input leg
> >> between
> >> the 47KOhm resistor and the chip (where the + sign in my diagram). Its
> >> purpose is to limit load dumps (this is in an automotive application so
> >> voltages can spike to 70V).
> >>
> >> Any spike over 5V gets dumped to ground.
> >>
> >> >
> >> > Derek Koonce
> >> > DDK Interactive Consulting Services
> >> >
> >> >
> >> > On 2/19/2013 9:04 AM, Yan Seiner wrote:
> >> >>
> >> >> I have a Max 197 AD connected as follows:
> >> >>
> >> >> Source - 47KOhm - + - MAX197
> >> >> |
> >> >> zener
> >> >> |
> >> >> ground
> >> >>
> >> >> With the source disconnected, the Max 197 reads about .22V.
> >> >>
> >> >> With it connected to a voltage source, it reads about what I expect
> >> >> (3.38V
> >> >> @ 12V source).
> >> >>
> >> >> Why would the MAX197 read a voltage with no voltage input? The other
> >> >> pins
> >> >> read 0.0 when disconnected; only the two connected to the zener show
> >> >> this
> >> >> weird voltage.

I let the battery charge for 24 hours with the switch on but no luck.
Today I did an online chat with the enjoydeal store website and they replied the
max amp draw is about 1.5

I am going to look into RC batteries as Stephan said they are typically meant
for higher output.

Norm

--- In Electronics_101@yahoogroups.com, "normnet2003" <normnet2@...> wrote:
>
>
>
> I'll try charging it again just in case.
>
> Norm
>
> --- In Electronics_101@yahoogroups.com, Frank Mead <wa6ujj@> wrote:
> >
> > It will come to you not fully charged...charge it for 10 hours and give it
> > a try...
> > good advice howard.
> >
> >
> > On Mon, Feb 18, 2013 at 12:27 PM, Howard Hansen <hrhan@> wrote:
> >
> > > **
> > >
> > >
> > > On 2/18/2013 6:56 AM, normnet2003 wrote:
> > > >
> > > > I recently purchased the following battery:
> > > >
> > >
http://www.ebay.com/itm/6800mAh-DC-12V-Super-Rechargeable-Lithium-ion-Battery-En\
ergy-Storage-Pack-/230806115118?pt=US_Rechargeable_Batteries&hash=item35bd1dd32e
> > > >
> > > >
> > > > I planed to use it to power a device requiring 12 volts at 4 amps for
> > > > 10-20 minutes however their doesn't seem to be any power when I plug
> > > > the 4 amp device to the battery as opposed to plugging it into the
> > > > car's 12 power supply.
> > > >
> > > > I thought 6800 ma meant 6.8 amps for one hour?
> > > > What lithium ion battery rating should I order for a 12 volt 4 amp
> > > > 10-20 minute requirement?
> > > >
> > > > Norm
> > > >
> > > > __
> > >
> > > I see the battery comes with a built in on-off switch. By any chance did
> > > you forget to turn the battery on?
> > >
> > > The other Howard
> > >
> > > [Non-text portions of this message have been removed]
> > >
> > >
> > >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>

Hi all,

I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not read
voltage right. It goes crazy we it sees voltage and jumps around and can stop
and see it for a 1/10 of a second, and then goes crazy again jumping all over. I
tried the battery, fuse, and bypassing the leads, but nothing seems to help. Has
anyone see anything like this? Is there any hope for it?

Travis

Travis,

Try connecting the probes together and set the meter on ohms. Then wiggle
the probe wires.

Rick

-----Original Message-----
From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of travispaul69
Sent: Wednesday, February 20, 2013 7:04 AM
To: Electronics_101@yahoogroups.com
Subject: [Electronics_101] Floating Voltage Problem on Multi-meter

Hi all,

I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not read
voltage right. It goes crazy we it sees voltage and jumps around and can
stop and see it for a 1/10 of a second, and then goes crazy again jumping
all over. I tried the battery, fuse, and bypassing the leads, but nothing
seems to help. Has anyone see anything like this? Is there any hope for it?

Travis

Rick
Replace thr fuses and see if you see the symptoms. A fuse can seem good when
tested but misbehave in circuit.

Also when shorting probes in continuity mode wiggle the plugs (where the probes
plug into the meter). Might be a bad solder joint there.

That meter gets some good reviews...

Dave


> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not read
> voltage right. It goes crazy we it sees voltage and jumps around and can
> stop and see it for a 1/10 of a second, and then goes crazy again jumping
> all over. I tried the battery, fuse, and bypassing the leads, but nothing
> seems to help. Has anyone see anything like this? Is there any hope for it?
>
> Travis
>
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>

Dave,

The fuse is only involved with current measurements AFAIK.

Rick

-----Original Message-----
From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of DaveC
Sent: Wednesday, February 20, 2013 9:22 AM
To: Electronics_101@yahoogroups.com
Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter

Rick
Replace thr fuses and see if you see the symptoms. A fuse can seem good when
tested but misbehave in circuit.

Also when shorting probes in continuity mode wiggle the plugs (where the
probes plug into the meter). Might be a bad solder joint there.

That meter gets some good reviews...

Dave


> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not
> read voltage right. It goes crazy we it sees voltage and jumps around
> and can stop and see it for a 1/10 of a second, and then goes crazy
> again jumping all over. I tried the battery, fuse, and bypassing the
> leads, but nothing seems to help. Has anyone see anything like this? Is
there any hope for it?
>
> Travis
>
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>


------------------------------------

Please trim excess when replyingYahoo! Groups Links

Try discharging meter face electrostatic charge.  Wipe face with wet cloth
or aluminum foil.



Larry



From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of DaveC
Sent: Wednesday, February 20, 2013 11:22 AM
To: Electronics_101@yahoogroups.com
Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter





Rick
Replace thr fuses and see if you see the symptoms. A fuse can seem good when
tested but misbehave in circuit.

Also when shorting probes in continuity mode wiggle the plugs (where the
probes plug into the meter). Might be a bad solder joint there.

That meter gets some good reviews...

Dave

> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not read
> voltage right. It goes crazy we it sees voltage and jumps around and can
> stop and see it for a 1/10 of a second, and then goes crazy again jumping
> all over. I tried the battery, fuse, and bypassing the leads, but nothing
> seems to help. Has anyone see anything like this? Is there any hope for
it?
>
> Travis
>
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>





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

Its a DVM.

Sent from my iPhone

On Feb 20, 2013, at 10:56 AM, "Larry Beaty" <lbeaty@...> wrote:

> Try discharging meter face electrostatic charge.  Wipe face with wet cloth
> or aluminum foil.
>
>
>
> Larry
>
>
>
> From: Electronics_101@yahoogroups.com
> [mailto:Electronics_101@yahoogroups.com] On Behalf Of DaveC
> Sent: Wednesday, February 20, 2013 11:22 AM
> To: Electronics_101@yahoogroups.com
> Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter
>
>
>
>
>
> Rick
> Replace thr fuses and see if you see the symptoms. A fuse can seem good when
> tested but misbehave in circuit.
>
> Also when shorting probes in continuity mode wiggle the plugs (where the
> probes plug into the meter). Might be a bad solder joint there.
>
> That meter gets some good reviews...
>
> Dave
>
>> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not read
>> voltage right. It goes crazy we it sees voltage and jumps around and can
>> stop and see it for a 1/10 of a second, and then goes crazy again jumping
>> all over. I tried the battery, fuse, and bypassing the leads, but nothing
>> seems to help. Has anyone see anything like this? Is there any hope for
> it?
>>
>> Travis
>>
>>
>>
>>
>> ------------------------------------
>>
>> Please trim excess when replyingYahoo! Groups Links
>>
>>
>>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>

what kind of voltage are you checking?
three phase will have a wild leg and if our meter does not have a fast
enough sampling rate it will not read correctly

On Wed, Feb 20, 2013 at 2:07 PM, DaveC <davec2468@...> wrote:

> **
>
>
> Its a DVM.
>
> Sent from my iPhone
>
> On Feb 20, 2013, at 10:56 AM, "Larry Beaty" lbeaty@...> wrote:
>
> > Try discharging meter face electrostatic charge. Wipe face with wet cloth
> > or aluminum foil.
> >
> >
> >
> > Larry
> >
> >
> >
> > From: Electronics_101@yahoogroups.com
> > [mailto:Electronics_101@yahoogroups.com] On Behalf Of DaveC
> > Sent: Wednesday, February 20, 2013 11:22 AM
> > To: Electronics_101@yahoogroups.com
> > Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter
> >
> >
> >
> >
> >
> > Rick
> > Replace thr fuses and see if you see the symptoms. A fuse can seem good
> when
> > tested but misbehave in circuit.
> >
> > Also when shorting probes in continuity mode wiggle the plugs (where the
> > probes plug into the meter). Might be a bad solder joint there.
> >
> > That meter gets some good reviews...
> >
> > Dave
> >
> >> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not
> read
> >> voltage right. It goes crazy we it sees voltage and jumps around and can
> >> stop and see it for a 1/10 of a second, and then goes crazy again
> jumping
> >> all over. I tried the battery, fuse, and bypassing the leads, but
> nothing
> >> seems to help. Has anyone see anything like this? Is there any hope for
> > it?
> >>
> >> Travis
> >>
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> Please trim excess when replyingYahoo! Groups Links
> >>
> >>
> >>
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Please trim excess when replyingYahoo! Groups Links
> >
> >
> >
>
>



--
jeremy youngs


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

Opps!



From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of DaveC
Sent: Wednesday, February 20, 2013 2:08 PM
To: Electronics_101@yahoogroups.com
Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter





Its a DVM.

Sent from my iPhone

On Feb 20, 2013, at 10:56 AM, "Larry Beaty" lbeaty@...
<mailto:lbeaty%40windstream.net> > wrote:

> Try discharging meter face electrostatic charge. Wipe face with wet cloth
> or aluminum foil.
>
>
>
> Larry
>
>
>
> From: Electronics_101@yahoogroups.com
<mailto:Electronics_101%40yahoogroups.com>
> [mailto:Electronics_101@yahoogroups.com
<mailto:Electronics_101%40yahoogroups.com> ] On Behalf Of DaveC
> Sent: Wednesday, February 20, 2013 11:22 AM
> To: Electronics_101@yahoogroups.com
<mailto:Electronics_101%40yahoogroups.com>
> Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter
>
>
>
>
>
> Rick
> Replace thr fuses and see if you see the symptoms. A fuse can seem good
when
> tested but misbehave in circuit.
>
> Also when shorting probes in continuity mode wiggle the plugs (where the
> probes plug into the meter). Might be a bad solder joint there.
>
> That meter gets some good reviews...
>
> Dave
>
>> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not
read
>> voltage right. It goes crazy we it sees voltage and jumps around and can
>> stop and see it for a 1/10 of a second, and then goes crazy again jumping
>> all over. I tried the battery, fuse, and bypassing the leads, but nothing
>> seems to help. Has anyone see anything like this? Is there any hope for
> it?
>>
>> Travis
>>
>>
>>
>>
>> ------------------------------------
>>
>> Please trim excess when replyingYahoo! Groups Links
>>
>>
>>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Please trim excess when replyingYahoo! Groups Links
>
>
>





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

Ok, here is the latest update. I took it back apart again and left the battery
hooked up. I did a continuity check and the leads seemed to work perfect. I then
took both the fuses out and did checks and both seem perfect. I put them back in
and then did a check on the battery while it was still plug in. And this time to
my surprise it measured ok, but measured 6v for a 9v battery. I thought this was
a new battery but apparently it got mixed up with my new batteries. I put an
another battery (good one) and now it seems fine. The orginal battery must have
been in there maybe 5-8 years. I was really confused when it when bad because I
was troubleshooting a solar panel at the time. It started at 28 volts and then
fell to about 18 volts and then went crazy. I thought 'what the !@#$%'. I think
its  back to normal.

--- In Electronics_101@yahoogroups.com, "Larry Beaty" <lbeaty@...> wrote:
>
> Opps!
>
>
>
> From: Electronics_101@yahoogroups.com
> [mailto:Electronics_101@yahoogroups.com] On Behalf Of DaveC
> Sent: Wednesday, February 20, 2013 2:08 PM
> To: Electronics_101@yahoogroups.com
> Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter
>
>
>
>
>
> Its a DVM.
>
> Sent from my iPhone
>
> On Feb 20, 2013, at 10:56 AM, "Larry Beaty" lbeaty@...
> <mailto:lbeaty%40windstream.net> > wrote:
>
> > Try discharging meter face electrostatic charge. Wipe face with wet cloth
> > or aluminum foil.
> >
> >
> >
> > Larry
> >
> >
> >
> > From: Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>
> > [mailto:Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com> ] On Behalf Of DaveC
> > Sent: Wednesday, February 20, 2013 11:22 AM
> > To: Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>
> > Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter
> >
> >
> >
> >
> >
> > Rick
> > Replace thr fuses and see if you see the symptoms. A fuse can seem good
> when
> > tested but misbehave in circuit.
> >
> > Also when shorting probes in continuity mode wiggle the plugs (where the
> > probes plug into the meter). Might be a bad solder joint there.
> >
> > That meter gets some good reviews...
> >
> > Dave
> >
> >> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can not
> read
> >> voltage right. It goes crazy we it sees voltage and jumps around and can
> >> stop and see it for a 1/10 of a second, and then goes crazy again jumping
> >> all over. I tried the battery, fuse, and bypassing the leads, but nothing
> >> seems to help. Has anyone see anything like this? Is there any hope for
> > it?
> >>
> >> Travis
> >>
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> Please trim excess when replyingYahoo! Groups Links
> >>
> >>
> >>
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Please trim excess when replyingYahoo! Groups Links
> >
> >
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

Damn! I forgot to ask all of the dumb questions. Glad you figured it out.

Rick

-----Original Message-----
From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of travispaul69
Sent: Wednesday, February 20, 2013 5:36 PM
To: Electronics_101@yahoogroups.com
Subject: [Electronics_101] Re: Floating Voltage Problem on Multi-meter

Ok, here is the latest update. I took it back apart again and left the
battery hooked up. I did a continuity check and the leads seemed to work
perfect. I then took both the fuses out and did checks and both seem
perfect. I put them back in and then did a check on the battery while it was
still plug in. And this time to my surprise it measured ok, but measured 6v
for a 9v battery. I thought this was a new battery but apparently it got
mixed up with my new batteries. I put an another battery (good one) and now
it seems fine. The orginal battery must have been in there maybe 5-8 years.
I was really confused when it when bad because I was troubleshooting a solar
panel at the time. It started at 28 volts and then fell to about 18 volts
and then went crazy. I thought 'what the !@#$%'. I think its  back to
normal.

--- In Electronics_101@yahoogroups.com, "Larry Beaty" <lbeaty@...> wrote:
>
> Opps!
>
>
>
> From: Electronics_101@yahoogroups.com
> [mailto:Electronics_101@yahoogroups.com] On Behalf Of DaveC
> Sent: Wednesday, February 20, 2013 2:08 PM
> To: Electronics_101@yahoogroups.com
> Subject: Re: [Electronics_101] Floating Voltage Problem on Multi-meter
>
>
>
>
>
> Its a DVM.
>
> Sent from my iPhone
>
> On Feb 20, 2013, at 10:56 AM, "Larry Beaty" lbeaty@...
> <mailto:lbeaty%40windstream.net> > wrote:
>
> > Try discharging meter face electrostatic charge. Wipe face with wet
> > cloth or aluminum foil.
> >
> >
> >
> > Larry
> >
> >
> >
> > From: Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>
> > [mailto:Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com> ] On Behalf Of DaveC
> > Sent: Wednesday, February 20, 2013 11:22 AM
> > To: Electronics_101@yahoogroups.com
> <mailto:Electronics_101%40yahoogroups.com>
> > Subject: Re: [Electronics_101] Floating Voltage Problem on
> > Multi-meter
> >
> >
> >
> >
> >
> > Rick
> > Replace thr fuses and see if you see the symptoms. A fuse can seem
> > good
> when
> > tested but misbehave in circuit.
> >
> > Also when shorting probes in continuity mode wiggle the plugs (where
> > the probes plug into the meter). Might be a bad solder joint there.
> >
> > That meter gets some good reviews...
> >
> > Dave
> >
> >> I have an older Radio Shack Multi-meter, (Cat no 22-812) that can
> >> not
> read
> >> voltage right. It goes crazy we it sees voltage and jumps around
> >> and can stop and see it for a 1/10 of a second, and then goes crazy
> >> again jumping all over. I tried the battery, fuse, and bypassing
> >> the leads, but nothing seems to help. Has anyone see anything like
> >> this? Is there any hope for
> > it?
> >>
> >> Travis
> >>
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> Please trim excess when replyingYahoo! Groups Links
> >>
> >>
> >>
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Please trim excess when replyingYahoo! Groups Links
> >
> >
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>




------------------------------------

Please trim excess when replyingYahoo! Groups Links