Psu positive rail derivation
« on: September 22, 2020, 11:12:27 AM »

Attached is a schematic of a linear psu I draw. +/- 17v, made with lm317/337 regulators. Those rails are quite normal.

My doubt arise about the other two positive rails after the 10R/1000uf rc filter.

1.) ¿Is it ok to share this RC filter for two 78xx regulators? (7824 and 7812).

1.1) I expect to draw not much current from each 78xx regulator..(+100ma max), so i could have draw
       78L24/78L12 in the schematic... ::)

2.) ¿Or is it better to give each regulator its own input capacitor?.(smaller value).

3.) In any case i derived those additional rails from the same diode bridge.

Thank you for your help!

Jay x


Re: Psu positive rail derivation
« Reply #1 on: September 22, 2020, 04:27:10 PM »
Sure. It won't matter. You only need to get the ripple well within what the regulator's need to regulate. So you could probably skip quite a few of those parts depending on how much current is being drawn. 6800uF is a lot. You could stress upstream parts and the thing might take a while to turn off.

Also I would add protection diodes across output / input of regulators.


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