wallwarts and regulation..

Tony Allgood oakley at enterprise.net
Fri Mar 6 20:11:00 CET 1998

Terry said...

And for heaven's sake don't hook a pot up to an LM7805 and think you have
an adjustable regulator. It will regulate under load but not with respect
to the unregulated DC. I've tried it on the bench; it doesn't work.

I have tried this with 78L05 and it works OK. Now there are different
manufacturers of the 7805 chip and it could be that different designs push
more current down the ground pin than some of the others. This will lead to
changes in the output pd. Having said that, you might as well get a 317 and
the two resistors, one cap and two diodes... more elegant somehow. Horses
for courses as my mother used to say.

Tony Allgood, Cumbria, UK

e-mail: oakley at enterprise.net

My latest project; a rack mounted VCF module with warmth. See it at:


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