Chris Eddy wrote:

> Tjaart;
>
> I didn't read the whole thing, but got the gist.  I am usually a 'put a PIC
> in anything' guy, but my current limit was real simple.  A TIP family part

The reason I wanted to use a MOSFET and PWM was for (virtually)
zero heat build-up. I've built a jig with TIP122's and opamps to charge
a whole bank of NiCd's a year or so ago. I used positive feedback on the
opamps. The problem remains that  a 10ohm (or a 1 ohm, for that matter)
is going to heat up the whole box at 2A. The MOSFET also offers you a
nifty way of measuring the current (Vds) you don't have on a BJT.

A 17.7A, 50V, SMD, logic gate level MOSFET is around US0.50, which
is dirt cheap too.

I will put a schematic on my web page tomorrow or so.

Hey, it my challenge! I can set the rules! ;)

--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za

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