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  1. audioguru2

    LED Blinker/Flasher Circuit using bicolour led

    The datasheet of a CD4017B shows that its output current into a 2V LED when it has a 5V supply is only 3.5mA or less (looks dim). Your circuit is mixing an old TTL 555 with an output voltage fairly low with a Cmos 4017 that needs a fairly high clock input voltage. A bad mix.  I used a 74HC4017...
  2. audioguru2

    0-30V Stabilized Power Supply

    Why do you show an LT1038? it is obsolete and is not made anymore. It is impossible for it to dissipate 32V x 10A= 320W. Its datasheet shows that with a huge heatsink with fan or with liquid nitrogen for cooling it can dissipate only 120W. Its control circuit gives 10A only when its input to...
  3. audioguru2

    Transistor basic connection for switching

    Why do you show text that talks about an NPN transistor but you show a schematic with a PNP transistor? The Circuitspedia PNP circuit is missing the important diode parallel with the relay coil. The diode is shown on their NPN circuit.
  4. audioguru2

    0-30 Vdc Stabilized Power Supply

    Surface mount ICs on adapters? Solder that was dripped on from up high and heated with a blow torch? All I can say after seeing your project is "EEK!".
  5. audioguru2

    0-30 Vdc Stabilized Power Supply

  6. audioguru2

    0-30 Vdc Stabilized Power Supply

    My Rev 6 July, 2014 schematic shows that opamp U1 makes the 11.2V reference, U2 is for the voltage control and drives the output driver transistor with 0V to about +32V and U3 is for the current control and has an output from -1.0V to about +27V. If the output has a low voltage (or is shorted)...
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    I did not calculate it but I think a tiny surface mounted opamp for position U2 will get too hot if the hFE of the driver and/or output transistors is low.
  8. audioguru2

    Changing just the AC Frequency

    If you make a circuit that uses high frequency pulse-width-modulation for making the 60Hz sinewave then its could be 90% efficient and produce "only" 120W of heat when its output is 1200W. Then it would need a pretty big heatsink with cooling fins.
  9. audioguru2

    Changing just the AC Frequency

    Use the 120VAC 50Hz to drive a 110V 60Hz motor driving an alternator. Use magic to adjust the frequency Make an audio amplifier powered from 120VAC 50Hz with 120VAC 10A (1200W!) output and feed it a 60Hz sinewave. 
  10. audioguru2

    0-30V Stabilized Power Supply

    Maybe you use the power supply to test a 3A forward biased diode. Then the output transistor gets very hot.
  11. audioguru2

    0-30V Stabilized Power Supply

    Good luck trying to cool 114W so that the case is not too hot.
  12. audioguru2

    0-30V Stabilized Power Supply

    I wrongly typed 114A instead of 114W. A single 2N3055 will be at its maximum allowed chip temperature of 200 degrees C when it dissipates 115W and its case is cooled to no more than 25 degrees C with liquid nitrogen or something. A heatsink also gets hot even when it is huge and has a fan...
  13. audioguru2

    0-30V Stabilized Power Supply

    Your idea to use only one 2N3055 output transistor will have it burning hot (38V x 3A= 114A!) if the current is set to 3A and the output is shorted or has a very low voltage. Two output transistors share the heat. Their emitter resistors match them pretty well. Two output transistors at b1.5A...
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    The peak of 30.5VAC is 30.5V x 1.414= 43.13V. The bridge rectifier has diode voltage drops of 1.4V when there is no load so the positive supply will be 43.13V - 1.4V= 41.73V. If your mains electricity voltage rises then the opamps might be destroyed. I do not know why your voltage measurements...
  15. audioguru2

    0-30V 3A - I need some answers

    15A output current is much too high for this circuit designed for a maximum of 3A using two output transistors to share the heat. Your schematic shows only one 2N3055 output transistor so its maximum output current will be only 1.5A. There are three MC34071 ICs. Which one do you have a problem...
  16. audioguru2

    0-30 Vdc Stabilized Power Supply

    When you turn down P2 to zero then the project's output current should be no more than a few mA. The circuit reduces the output voltage with U3 and D9 to reduce the current. When the current is limited to a few mA then the anode of D9 is 0V and its cathode which is driven from the output of U3...
  17. audioguru2

    0-30 Vdc Stabilized Power Supply

  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    I use copper wire, not rice wire. They put rice in everything they make, especially batteries.
  19. audioguru2

    0-30 Vdc Stabilized Power Supply

    5V on 10 ohms produces a current of 500mA (0.5A). Then the voltage across R7 is 0.235V. On your schematic, C is the ground for the current regulator. The output ground is its input signal and the 11.2V is its reference voltage.
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    The Chinese meter is messing up the voltage and current of the power supply project. Try the power supply project without the Chinese meter. Measure the voltage across R7 then calculate the current in it. The voltage across R7 will never be more than 1.414V when the current in it is 3.0A or...
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