"Christopher X. Candreva" wrote:
> Turns out the board wasn't putting out +15v either. Either I was asleep when
> I tested this the first time, or I ran it too long testing.
>
> Turns out the 1n100 diode between the +15 regulator and ground shorted out.
> This is a 100 piv switching diode. So far my searches for 1n100 have turned
> up nothing, not even a 'discontinued' mention, except for NTE's cross to a
> NTE109.
NTE109, ECG109, SK3090, or Radio Shack 276-1123 (!)
> On the other hand, 1n914/4148's are cheap and plentifull (even CrapShack has
> them). They are only 75piv though. My basic power supply knowledge is making
> me ask:
>
> 1) Why the hell do we need a switching diode on the output of a voltage
> regulator in the first place ? Isn't that what the regulator is supposed to
> do ?
>
> 2) Since this is a 15v supply, is a 100piv diode necessary ? Even the 75piv
> seems like it would be overkill. If it would be a bad idea to use the 75piv,
> I'm assuming the answer to 1) will tell me, though it does appear the
> Asteroids supply uses the 1n914
>
> The only thing I can figure is it's a clamping diode, but I can't imagine
> where the 75v+ spikes would be comming from.
>
> -Chris
>
> ==========================================================
> Chris Candreva -- chris@westnet.com -- (914) 967-7816
> WestNet Internet Services of Westchester
> http://www.westnet.com/
Received on Fri Oct 15 03:32:44 1999
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