Al salaam a'alaykum Bob

09 Nov 03 11:15, Bob Lawrence wrote to David Drummond:

 DD>> I have a "portable" DVD unit which runs on a (switch mode)
 DD>> mains power pack. The power pack produces 6.3v DC at 3A. How
 DD>> hard would it be to produce a switch mode supply to produce
 DD>> that output, but from a (nominal) 12V DC supply? 

 BL>  Shit easy.... but why not use a series regulator? It's only 20
 BL> watts extra loss.

 BL>  You can buy switch mode regulator ICs, but you have to wind your own
 BL> switching coil and stuff around with fast diodes. If you're not
 BL> worried about battery life, I'd use a simple series regulator with a
 BL> nice big transistor on a nice big heatsink. If you need a dropping
 BL> resistor, use a 12V light bulb across the regulator.

I had thought of using a "simple series regualtor" but this is
intended to be used at my "country weekender" where I don't have
mains. Battery life _is_ a consideration.

Regards,
David

--- Msged/LNX TE 06 (pre)