Hi all,
I've built a nice little 78S40 regualtor which works fine, my first questions is this seems to be a old IC according to some websites, though if this is the case, whats the new versions number ? Can't even find it on Motorolas site....
Second question is its limited to a 1-40VDC voltage (not the IC supply voltage), which is understandable, but if its using this (assuming 40VDC DC output) output voltage to regulate itself, then feeding in like 100VDC would appear to blow the chip up since its only 40VDC rated, so if the feedback voltage has a upper limited of 40VDC (like the datasheet says 1V-40VDC output) then would it work to simply feed in say 80VDC and place a 40Vzener to the feedback pin on the IC, the IC would see then 40VDC and regulate it, but the actual output would be 80VDC, has anyone tried this type of thing ?
I thought id ask about this one since its my first PSU of this type, I'm aware of risks and dangers before anyone gets uptight about it, I do mean this since Ive spent the last 10 or so years repairing all kinda of PSU units, though building one from scratch yourself tends to open up a few more doors than one is used to ;)
Cheers, Chris