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Subject: Re: Getting rid of that damn noise.
From: Rob & Liz Ward (
Date: 2001-12-29

Great work. I will take a look.


----- Original Message -----
From: "Joachim Schiffer" <>
To: <>
Sent: Saturday, December 29, 2001 10:36 AM
Subject: Re: Getting rid of that damn noise.

> Hi Rob,
> I must apologize for the errors in the schematics...
> I have just made lists of connections
> (for example U11,5 -> U6,5)
> and when i was finished, I put them together.
> I didn't analyze the circuit (and i don't have the time for that
> at the moment), so i didn't notice the bugs.
> I also don't have the time to re-check the whole
> circuit again (it took a few days...), so it's the best,
> if I check single connections, if they look strange.
> > The comp would be the feedback i/p (normal operation = 1.25V?). Driving
> > this pin high (via the diode D8) stops the switching, and
> > using the a/d to read it would tell whether the battery is charged. This
> > means the battery charger is logic-levelled controlled - ON or OFF !
> >
> > This is a rather crude battery charger that would appear (from the
> > circuit) to feed as many volys into the batteries as possible. Please
> > the /COMP wiring for correctness.
> >
> There were indeed bugs around the /COMP pin.
> I have attached a new version of the second pdf.
> The values of some Resistors may be wrong, too.
> They are sometimes badly printed, and there are
> two notations. Sometimes it's 103, sometimes it's
> 10B or 01C. It's also not easy to read sometimes,
> for example if a B looks like a 3...
> > I think T3 should be PNP, not NPN.
> T3 is labeled FZT849, i think it's definitely NPN.
> > Are you sure C12 is correctly wired?
> C12 is correctly wired, but there was one additional
> connection missing, I fixed it.
> Also, i found out, that D12 is a zener diode (2.7 V) and
> is connected R20, not to VSUP directly.
> > Of course, they could have some weirdo circuit here, but it certainly
> > resembles what I would expect.
> > Good luck.
> Thank you :-)
> /Joachim

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