"John Larkin" wrote in message
...
On Sun, 15 Jan 2012 22:15:02 -0000, "Ian Field"
wrote:


"Jim Thompson" wrote
in
message ...
On Sun, 15 Jan 2012 16:43:18 -0500, "Martin Riddle"
wrote:


"Jim Thompson" wrote
in message ...
Here you go...

http://analog-innovations.com/SED/Bi...ubSwitcher.pdf

I figure, if you had a mind to, you could add regulation by running
this dude in burst mode, by stopping the 555 via its RESETbar input.

Diode D7 prevents some really weird behavior from back conduction. If
there were a need to tighten up the efficiency, I'd replace it with
another P-channel, body in the opposite direction from MP1 (for lack
of finding a suitable transistor, modeled as a 0.3 Ohm device
extrapolated from my vast CMOS device library :-). Then I'd use a
comparator to make the drop like a near ideal diode as in...

http://analog-innovations.com/SED/Pe...rIsolation.pdf


Component values included!

Cheers



I always do that. I had that info the very first day, as I alluded in
an early post (I verbally provided the results, same as the sims now
posted... which got me "naa, naa, naa poo poo"), so I just let Larkin
run off at the mouth, just for the sport of it ;-)

...Jim Thompson


You might impress a few simple people, but it certainly won't do what I
set
out to achieve.


JF will love it, since it has a 555.

It may have been possible to achieve something aproximating to regulation by
externally pulling the 5k/5k/5k divider, but it would be a huge comromise.

There's a schematic taking shape and tempting me to put pen to paper.

But I'm inclined not to do it all for the 2 principle knowitalls that in
reality don't know a fraction of what they'd like us to believe.