audioguru Posted January 26, 2011 Report Share Posted January 26, 2011 I built it (3A version)Which version? Which opamps?I have a few issues:1) current limiting LED is always on (if I turn current pot to max value it even lights more)Opamp U3 us used as a comparator with a voltage gain of about 200,000. Its output switches on and off, not as a linerar fader. It turns Q3 off when the output current is less than the setting of the current-setting pot. I just can adjust minimum voltage to 50mV with voltage trimmerIf there is a load then the voltage setting pot should adjust the voltage to 0.0V. The offset adjust trimpot sets the offset so the output can go to 0.0V when there is a load.C7 is an electrolytic type that produces "dielectric absorption" which produces an output voltage when there is no load. A film type of capacitor for C7 fixes it. what can I adjust with other two trimmers?I told about the offset adjust trimpot. There is a voltage trimpot that sets 30.0V when the voltage pot is at max and there is a current trimpot that sets 3.0A when the current setting pot is max and there is enough load.However, PSU works fine, the maximum output voltage with no load is 40V.You should adjust the voltage trimpot so that the max output voltage is 30.0V so that the circuit regulates properly without ripple when it has a load. Quote Link to comment Share on other sites More sharing options...
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