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  1. audioguru2

    0-30V Stabilized Power Supply

    You have many serious problems, probably caused by wiring errors. 1) The output of U1 should be +11.2V but yours is 11.8V which is only 5% high so it is fine. 2) The output of U2 should go from 0V to +33V when the voltage setting pot is adjusted. It might always be +34V if you have the pins of...
  2. audioguru2

    0-30V Stabilized Power Supply

    When the output is shorted or set to a low voltage then at 10A the heating is 40V x 10A= 400W! You will need many output transistors on huge heatsinks and a fan. You must parallel a few driver transistors, each with an emitter resistor and a huge heatsink. The opamp U2 might not be able to...
  3. audioguru2

    0-30V Stabilized Power Supply

    Then at maximum output current you might have ripple instead of voltage regulation. That was a problem with the original circuit that used a 24VAC transformer.
  4. audioguru2

    0-30V Stabilized Power Supply

    U2 is a non-inverting amplifier. Pin 3 is its input and pin 2 is used for negative feedback. If you ground pin 3 then the output transistors will turn off and the load will discharge the output capacitor. If the load current is low and the output voltage is high then it might take a long time...
  5. audioguru2

    0-30V Stabilized Power Supply

    Why do you add a switch to force the output to the positive unregulated voltage? Don't you want a switch to force the output to 0V? Then add a switch to the input of U2 and ground.
  6. audioguru2

    0-30V Stabilized Power Supply

    Yes.
  7. audioguru2

    0-30V Stabilized Power Supply

    The rectified and filtered +40V can light an LED if it has a current-limiting resistor. An LED is 1.8V to 3.8V depending on its colour. If the LED is a 1.8V red one then for 15mA the resistor is (40V - 1.8V)/15mA= 2547 ohms. Use 2.7k. Its power is a little more than 1/2W so use a 1W or 2W resistor.
  8. audioguru2

    0-30V Stabilized Power Supply

    Since your U3 opamp does not perform correctly as a comparator then replace it.
  9. audioguru2

    0-30V Stabilized Power Supply

    The current in the pots is very low so thin wires can be used.
  10. audioguru2

    0-30V Stabilized Power Supply

    R7 is 0.47 0hms and is in series with the load. Load current causes a voltage drop across R7. 3A x 0.47 ohms= 1.41V. With a low load current then the voltage across R7 is very low. The voltage across R7 is fed to pin 2 input of U3. U3 is used as a comparator. Normally its output is high so the...
  11. audioguru2

    LM317 Calculator

    I will NEVER download a zipped file from somebody I do not know because it might be a computer virus or SPAM advertising. It is SIMPLE to calculate resistors for an LM317. The resistor from the output pin to the ADJ pin is 120 ohms and it has 1.25V across it so the current is 10.42mA. Then the...
  12. audioguru2

    0-30V Stabilized Power Supply

    If you made the circuit on a solderless breadboard then the opamps are probably oscillating which makes them maqlfunction and get hot.
  13. audioguru2

    0-30V Stabilized Power Supply

    Which version? The original, a modified one or the latest modification? Which transformer? 24VAC, 28VAC or 30VAC? Which opamps? TL081, MC34071 or TLE2141? The output should be able to go from calibrated 0V to calibrated 30.0V. Measure the output voltage of U1. It should be about 11.2V. The...
  14. audioguru2

    Voice Activated Switch, seeking project info

    The MC2830 IC is obsolete and has not been made for many years.
  15. audioguru2

    Realization of an audio amplifier ..

    Are you allowed to copy the schematic of an amplifier? There are thousands on the internet.
  16. audioguru2

    how does a PULSE code MODULATION WORKS?

    A code that is 14 is made with three bursts of 38kHz (the ones) with a short pause between followed by a long pause (the zero). Look at the datasheet of a TSOP1738 to see.
  17. audioguru2

    0-30V Stabilized Power Supply

    It makes a HUGE difference. Without the ground at the 28VAC then the full-wave rectifier works properly and the negative supply works properly. With the ground then the rectifier is half-wave and the negative supply does not work. Yes it is necessary for the U3 current regulator to cause the...
  18. audioguru2

    0-30V Stabilized Power Supply

    I think Multisim did not learn about electronic circuits properly. It does not know about the extremely simple negative supply source so you had to add a 1.3V battery in series with it. It does not have a model of the modern TLE2141 opamps. A little capacitor (C2) cannot burn and it will not...
  19. audioguru2

    0-30V Stabilized Power Supply

    Use 10uF for a film capacitor for C7 with a 4.7k/0.5W resistor in parallel.
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    The datasheet for the OLD TL08x opamps lists the specs with a plus and minus 15V supply. The minimum Common-Mode Input Voltage Range (where its inputs work properly) is -11V. Its typical is -12V. So some opamps fail when an input is 4V above the negative supply voltage and MOST fail when it is...
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