Author Topic: Negative power supply  (Read 1345 times)

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Offline electros6Topic starter

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Negative power supply
« on: January 31, 2014, 02:15:53 pm »
I tried to do dual power supply. The positive part works fine but the negative part is oscillating. I have attached the basic schematics .  I don't have digital scope so I have drawn the output that I have scene in my analog scope . Please guide
 

Offline Zero999

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Re: Negative power supply
« Reply #1 on: February 04, 2014, 10:45:46 pm »
QWhat a strange circuit.

It oscillates because the phase shift is 180 at a frequency when the gain is above one so negative feedback becomes positive feedback. Add a compensation capacitor into the feedback loop to reduce the high frequency gain so the gain with 180 degree phase shift is under 1.
 


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