On 5th Aug 2004 Marcel Duchamp wrote :

> Let us know how it works out

I finally got together with Russell and we (ie Russell, me watching)
came up with this FET version

http://home.clear.net.nz/pages/joecolquitt/mc34063.html

It seems to deliver what's needed, and I'll be shipping one off on
Monday (well, two actually, Russell gets a PCB version too, I'd
be interested to know what value the inductor worked out to be)
to the customer to try on his motor

I have noticed a little better performance with a second version. It
has a very slightly lower Rsc (0R1 in this diagram), and a BYV28-
200 diode. I'll do a bit more testing after I've heard whether the
circuit generally is any good for the customer. With the i/p at 13.5V,
which might be more realistic as the circuit wil be powered from an
automotive battery, the o/p voltage stays up at 20V

The FET is quite a lot larger than necessary. One concern that
Russell had was that the 270R gate pull-down would get hot, but
I can't say I've noticed, and nothing else apart from the load resistor
heated up, so it'll just be down-sizing the FET and then probably
leave it alone

Thanks for your help Russell

_______________________________________________
http://www.piclist.com
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist