Re: Space Duel Power Supply -- Part II

On Fri, 15 Oct 1999, Rodger Boots wrote:

> Then it must be there to keep the output from getting driven
> negative, probably during power-down of the game.

That makes sense. Here's a bad ASCII diagram:
    |\
 Vin| \__________ +15
----| / | |
    |/| -+ -
      | -.1uf ^ 1N100
      | | |
 _____|__________
Gnd

> > > voltage. You can use any diode with a HIGHER PIV, but not lower... if the
> > > orig was 100 PIV, go down to RAT shack and get a diode with 100+ PIV --
> > > many go 200, 300, etc. The diode there is non critical in almost every
> > > spec except PIV :)

> The diode has to turn on before the innards of the regulator do.
> Germanium turns on at about .2 volts instead of the .65 of silicon.
> Schottky is somewhere in between, and you will have a hard time
> finding a 100 volt Schottky. But as long as it's good for at least
> 20 or 25 volts it should be fine.

Difference of opinion. :-) But this is actually what I was originally
thinking. RS has the 1N34A, which is germaniuam, but only has a PIV of 60v.
Unless this supply is powering the counter or something, I can't imagine
it's going to have such large voltages to deal with.

Of course the real solution is to get the right part. Makes me REALLY wish I
had a decent place to buy from locally. Speading $4 shipping on a $.50 part
drives me nuts.

I'm going to trace through this some more to see what this +15 drives, other
than the vector generator sections. Anyone who knows why such a high PIV is
needed feel free to smack me upside the head.
:-)

-Chris

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Chris Candreva -- chris@westnet.com -- (914) 967-7816
WestNet Internet Services of Westchester
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Received on Fri Oct 15 10:19:32 1999