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  1. audioguru2

    0-30V Stabilized Power Supply

    You are measuring the voltage drop across the resistance of the wires connected to your short circuit. Your voltage meter is connected to the output terminals of your project, not to the short circuit. Try connecting a very thick wire with a short length directly between the output terminals of...
  2. audioguru2

    0-30V Stabilized Power Supply

    Sorry, I cannot understand your broken English. Russian? Your youtube link does not work. Do svidaniya.
  3. audioguru2

    LM384N/NOPB-IC amplifier with heatsink

    The TDA2009A dual amplifier is available inexpensively almost everywhere and can be bridged. But the datasheet is a nightmare, it shows the bridged circuit but says NOTHING about its supply voltage for it to have an output of 18W into 8 ohms at 1% distortion. I guess its supply voltage is 20V.
  4. audioguru2

    LM384N/NOPB-IC amplifier with heatsink

    The datasheet for an LM384 amplifier IC shows that with a 20V supply its output is about 3W into 8 ohms before clipping. It heats with about 2.5W so it will need a pretty good heatsink that is not available anymore. How will you cool it? The maximum 20V current is (3W + 2.5W)/20V= 275mA. Radio...
  5. audioguru2

    0-30V Stabilized Power Supply

    Thanks, Peter. I did not organize the changes since I never built and tested this project, I simply added my opinion about how to fix its problems. The original project had many errors.
  6. audioguru2

    LM384N/NOPB-IC amplifier with heatsink

    The LM384 is VERY old and needs the obsolete heatsink to survive. Use a newer amplifier IC. With the obsolete heatsink its output was 5.5W with horrible sounding 10% clipping distortion. Its output before clipping was about 4W which sounds only a little louder than a cheap clock radio. A modern...
  7. audioguru2

    0-30V Stabilized Power Supply

    The MJ21194 has very powerful specs on its ON Semi datasheet. But yours has a tiny little chip inside and is marked Mexico and with the same date as the cheap ones sold by a Chinese company shown in Google Images. Why are American transistors made in Mexico sold cheaply in China?? Because they...
  8. audioguru2

    0-30V Stabilized Power Supply

    I have never bought any parts from ST Micro. They are Italian and I am Canadian.
  9. audioguru2

    Help in Understanding Relay

    Each contact can switch up to 5A so the total for all three contacts is 15A. We do not know the voltage the contacts will switch so we cannot calculate the power (voltage times current) that is switched to a load. EDIT: You are very confusing because your relay contacts are not connected to...
  10. audioguru2

    PLS HELP ME WITH THIS SIMPLE COMPUTATION

    Why are you connecting a 28VDC LED lamp to 220VAC? It will EXPLODE! LEDs need DC and they need their current limited by a series resistor or circuit. The relay is simply three on-off switches that all work at the same time. When it is turned on then the contacts are turned on. The power...
  11. audioguru2

    0-30V Stabilized Power Supply

    Some fake transistors have some tin foil inside instead of a transistor chip. :( In Google I found your transistors being sold in China:
  12. audioguru2

    Help in Understanding Relay

    The coil ratings and the contacts ratings of a relay are completely different. You show the 12V adapter powering the coil of the relay. The current is low but you do not say the coil's current. The contacts of your relay are not connected to anything so they have no current. Each contact can...
  13. audioguru2

    0-30V Stabilized Power Supply

    Yes, your heatsink is much too small.
  14. audioguru2

    Confussing Loading Computation

    If the speaker part is 8 ohms and the siren circuit gives it a squarewave of plus and minus 5.5V over and over then the power in the speaker is (11V squared)/8 ohms= 15.1W for half the time which is an average power of only 7.5W. Maybe the siren's power rating is its (fake) peak power of 15.1W.
  15. audioguru2

    0-30V Stabilized Power Supply

    I am glad that increasing the value of R17 fixed your problem and it is wonderful that you received samples of the opamps.
  16. audioguru2

    0-30V Stabilized Power Supply

  17. audioguru2

    0-30V Stabilized Power Supply

    I do not see why the U1 voltage reference would cause a voltage spike when powered or shutdown. If it did then it would be attenuated by R8 and C4 on my schematic. You can use a 12V linear regulator IC instead if you want.
  18. audioguru2

    0-30V Stabilized Power Supply

    Picmaster's pcb is perfect.
  19. audioguru2

    0-30 Vdc Stabilized Power Supply

    The solution is to make the project properly using a 28VAC or 30VAC transformer then the rectified and filtered unregulated voltage with no load is 31VAC x 1.414= 43.8VDC - 1.4V= +42.4VDC. With a 3A load on the project then the rectified and filtered unregulated voltage will be +40.4VDC. It is...
  20. audioguru2

    0-30V Stabilized Power Supply

    You must properly disable the opamps you will not be using. Even though they are not used their idle current causes heating in opamp U2 which might be too high. The opamps in an MC34074 have a maximum input offset voltage of 5mV so when the voltage setting pot of this project is set to zero...
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