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Power supply mod

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MikeK:
After building my Elenco power supply kit I realized it has no reverse protection diodes on the regulators.  The series pass transistor at the 5V regulator confuses me, so I'm not sure where to put the diode.  Please comment (my changes are in red):

Rerouter:
A, the regulator still gets evened out by the series resistor on the regulator,

the 100nF on the outputs are a nice touch, for low esr, but for the variable side, it would be better to have them on the inputs, and as close to the regulator as possible, even sharing pins if possible,

MikeK:
I can add them on the inputs, but shouldn't I keep them on the outputs?  Don't the regs still produce ripple?

Rerouter:
what the 100n capacitors you see on other supplies is to handle transients, ripple usually comes from the input side, by having a very low ESR capacitance at the input pins, you can help smooth it out a bit more than it would on the output,

low esr ceramics help couple the AC component to ground, and its always better to get rid of it on the input,

MikeK:
Okay, thanks!

Now, if I wanted to have a switch for the outputs (so that the big caps don't continue to power my circuits when I switch off the power supply) can I just run the COM line through an SPST?

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