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  1. audioguru2

    0-30V Stabilized Power Supply

    1) Your parts re-numbering causes a nightmare to troubleshoot it. 2) Some of your text overlaps other text. 3) Many of the external connections are confusing. 4) The schematic is too small or is too large. Then maybe I will not look at your problems anymore.
  2. audioguru2

    0-30V Stabilized Power Supply

    Liquibyte, The parts designation numbers on your parts layout are all mixed up: 1) U1 on the original and on my modified schematic has it as the 11.2V reference but your U1 is the current regulator. 2) U2 on the original and on my modified schematic is the voltage regulator but your U2 is...
  3. audioguru2

    0-30V stabilized power supply: construction problem.

    The original circuit has many parts overloaded so they fail and it does not meet its spec's for 30VDC at 3A. Therefore a few threads were made in the forum showing an improved circuit with a modified schematic and parts list. I am attaching them here.
  4. audioguru2

    0-30V Stabilized Power Supply

    Liquibyte, Your unregulated positive supply is about +46V. It is reduced to about +36V with the series 10V zener diode. Then pin 7 of U1 and U2 should be about +36V but pin 7 of your U1 is MUCH TOO LOW!
  5. audioguru2

    My ZVS driver gets very hot on one Mosfet only

    The simple circuit is completely symmetrical so each Mosfet conducts the same if the input squarewave is symmetrical. What provides the input signal and is its waveform symmetrical? What is the frequency?
  6. audioguru2

    0-30V Stabilized Power Supply

    Good. Good. R10 should be 1k ohms with the TLE2141 opamp. The 11.2V reference circuit using u1 is very simple. Its supply can be anywhere from 14v to 44V. Measure it. Make sure its zener diode is 5.6V at 5mA because a 100mA zener diode voltage will be low like yours is.
  7. audioguru2

    0-30V Stabilized Power Supply

    1) Which opamp part number is your U2? 2) What is the value of RV1? 3) Do you have an R10 connected to the slider of RV1? Measure the voltage at the output of U1. It should be 11.2V. The voltage pot feeds 0V to 11.2V to the input of the output amplifier (it has U2 in it) that has a voltage gain...
  8. audioguru2

    0-30V Stabilized Power Supply

    I do not know what "pulling" is. If RV1 can adjust the output +/-100mV then that is good. Simply adjust for 0V. Then you have something very wrong. I will look back to see what modifications you have.
  9. audioguru2

    0-30V Stabilized Power Supply

    Set the voltage pot to zero and adjust RV1 so that the output voltage is exactly 0V. You will be able to adjust it from about +50mV to -50mV. If the output capacitor C7 is an electrolytic type then it will have dielectric absorption which will cause the output voltage to be a little positive...
  10. audioguru2

    0-30V Stabilized Power Supply

    The original project used a 24VAC transformer that was overloaded at maximum power. It produced about 25.5VAC with no load then its peak voltage was 36V that was reduced to 34.7V by the bridge rectifier. The opamps used this as their positive supply but U2 also has a -5.6V negative supply so its...
  11. audioguru2

    0-30V Stabilized Power Supply

    The forward voltage drop of a diode depends on its current because it has some resistance. Without a load on this project its opamps current is only 9mA for U1 and 3.4mA for each of U2 and U3. At a few mA the voltage drop of a 1N400x rectifier might be only 0.5V.
  12. audioguru2

    0-30V Stabilized Power Supply

    With a 12V zener diode reducing the raw positive supply to opamp U2 then your project will not produce regulated +30V at 3A. It might produce regulated 27V with no load, 25V at 1.5A and 23V at 3A. Its output will have lots of ripple at high voltage/high current.
  13. audioguru2

    0-30V Stabilized Power Supply

    Like opamp U2, U1 also does not have a negative supply. With a good 28V transformer, with no load its supply is +40.5V which is less than its 44V maximum. U1 can be powered from the 10V zener diode together with U3 if you want and if the zener diode is rated at 1W then it will get only fairly warm.
  14. audioguru2

    electromechanical circuits

    You are wrong, Kevin. ALL opamps have a NPN emitter-follower at the output to source current and an PNP emitter-follower transistor at the output to sink current. Maybe you are thinking about the output of a comparator that does not have emitter-follower outputs so it is simply an NPN open...
  15. audioguru2

    0-30V Stabilized Power Supply

    Correct.
  16. audioguru2

    0-30V Stabilized Power Supply

    Absolutely NOT! You have more than 3A passing through the zener diode because it also feeds the driver and output transistors which do not need their voltage reduced. With a current of more than 3A then the poor little zener diode will blow up like a bomb.
  17. audioguru2

    voltage divider with diode

    An audio amplifier NEVER transfers maximum power to a loudspeaker because then the amplifier output impedance must be as high as the speaker impedance. Instead an audio amplifier has an extremely LOW output impedance so that it damps the resonances of a loudspeaker. Audio amplifiers usually...
  18. audioguru2

    0-30V Stabilized Power Supply

    The high supply voltage problem has already been worked out for opamp U3 because it uses a -1.3V negative supply. So its positive supply pin is powered through a 10V zener diode which reduces its supply voltage by 10V. Power your U1 and U2 from this zener diode too to reduce their supply...
  19. audioguru2

    0-30V Stabilized Power Supply

    Using a TLE2141 opamp for U2, a negative supply is not needed. The inputs will work slightly below ground but go down to only 0V and the output will go almost to ground but goes only as low as about +1.1V in this circuit.
  20. audioguru2

    0-30V Stabilized Power Supply

    Years ago I selected an opamp with a 90V maximum power supply rating but it was not available frequently and was not common in distant countries. Connect the + supply pin of all the opamps to the 10V zener diode, and feel if it gets hot.
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