Re: [Electronics_101] Re: Crystals and oscilators and such - pic
- On Saturday 30 April 2005 03:06 pm, Dave Mucha wrote:
> > > EMIGUARD product.Yeah, I know about them.
> > >
> > > Ferrite cores on both legs and a varistor mixed in there
> > > somewhere.
> > Varistor?
> The varistor is a surge protection device that is connected directly
> across the AC input.
> This would be a clamping device. They are common in the cheap power
> strips you buy.
> Not sure where it would have a use here though.Maybe they put one in there to keep stuff from getting to the logic?
> > You miss the point, though. This sort of thing started showing upOr maybe it's to keep other noise in the environment from getting in...
> > all over the place (along with ferrite beads and lots of other filtering)
> > when noise emitted by various bits of digital electronics started to
> > become a problem with regard to interfering with radio and tv
> > communications. This isn't so much to protect the circuitry that's in the
> > box as it is to keep those really sharp transitions put out by the chips
> > in the box from getting out, and causing interference.
> > This is also why so many keyboard and mouse and monitor cables have
> > a fat spot where there's a large ferrite bead included in the cable.
> > Thanks to the FCC for all that sort of thing...
> There are two of thses puppies on the main sensing line that reads
> the analogue voltage of the machine after a voltage difiver and
> filter. that divider and filter are external so one would not expect
> a huge amount of noise in this panel. better safe than sorry thought.
Hard for me to say without looking at the unit, or a schematic of it.
> As for noise eneraged from the circuit, the most crude stepper motorOk.
> driver will have orders of magnitude greater generated noise. This
> circuit is only to monitor if the parameters are out, then tell which
> way to move to get it back.
> I have not pulled one of the components as it is a customers boardYou could get some idea if our guesses were close by just measuring across one
> and it does not appear that the problem is in the area of these parts.
of them without pulling it. If it's >10 ohms, or close to that, then it's
probably what we're talking about here.
> The power supply is +12/-12 to the LM324, and I think the op-amp isEasy enough to verify. Put your meter on an output, then short both inputs
with a small screwdriver (most all circuits have enough resistors in there to
make this not be a problem). The output should go to zero for bipolar
supplies. Most common op amp failure I run across all the time is a short to
one of the supply rails, most commonly the negative one in my experience.
> It appears to be the relay and not the logic. the realy is alsoDriven by one of the op amps, by any chance?
> powered thru one of these chips, but I think the relay itself is bad.
- After a couple e-mails with the engineering department, they think it
might be a capacitor.
link to data sheets
The equivalent circuit shows the two outter legs as being inductors
with a non polarized capacitor in the center.
--- In Electronics_101@yahoogroups.com, "Stefan Trethan"
> On Fri, 29 Apr 2005 20:49:07 -0000, Dave Mucha <dave_mucha@y...>
> > Op's files sections, last item zzz-resonator
> > Dave
> That's really looking like one of those resonator buggers.. maybe a
> You poke it with probes already?
> look here:
> that is the same MFG logo...