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Old 19th Oct 2018, 7:57 pm   #3
cmjones01
Nonode
 
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
Default Re: Retired Texas TI99/4A engineer needs help please.

Interesting circuit. Is that really a switching buck converter made with a 723 regulator? That had the reputation of being one of those things that was shown in the data sheet but wasn't recommended in real life. L4 is the giveaway. If I haven't got the wrong end of the stick, then D9 and D10 probably both need to be fast diodes. D9 is doing the heavy lifting so D10 could probably be a 1N4148 at least just for testing. A random schottky diode from a scrap power supply would also do.

Chris
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