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I have attached the schematic of a power supply design. The +12V works as designed under load. As soon as I apply a load (250mA) to the -12v voltage drops to 0. My first guess would be faulty regulator, as I had to buy off Amazon due to shipping. I do not suspect the output capacitor size to be a problem as the output after the regulator is dc (0 Hz) so the capacitive reactance should be extremely large, with no loading effect on the output. If we assume some 60 Hz ripple the capacitive reactance is still around 27k ohms so it shouldn't affect the circuit. After turning off supply and restarting -12V is present until load is applied to that circuit. I just want to make sure there isn't anything else I could be missing.

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Josher
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    Does this answer your question? https://electronics.stackexchange.com/questions/664040/dual-voltage-power-supply/664044 – GodJihyo Apr 25 '23 at 18:27
  • No this doesn’t answer the question. – Josher Apr 25 '23 at 20:46
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    Okay, just had that question yesterday, thought your problem might be the same. So what happens to the voltage at the input to the 7912 when the output is loaded? Are the + and - outputs of the rectifier even with respect to ground? Do you have the regulators properly heatsinked? Those regulators are normally pretty forgiving of things like capacitor values. If the input voltages are good (and enough to be more than the output plus dropout voltage) then a bad regulator is sounding more likely. – GodJihyo Apr 25 '23 at 21:31
  • We are all set with this! I appreciate your assistance. Thank you again! – Josher Apr 28 '23 at 19:56
  • So what did it turn out to be? – GodJihyo Apr 28 '23 at 20:06

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