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  1. audioguru2

    0-30V Stabilized Power Supply

    The peak of 28V RMS is 28V x 1.414= 39.6V. The bridge rectifier drops 1.2V when the current is very low so the positive voltage is 39.6V - 1.2V= 38.4V. The opamp U2 is the only one using the full 38.4V which is not near the maximum allowed voltage of 44V. I selected a Hammond high quality...
  2. audioguru2

    voltage divider with diode

    On the other website forum I asked you to post the schematic but you didn't. I think it is part of the bootstrapping of the driver transistor's collector load.
  3. audioguru2

    0-30V Stabilized Power Supply

    I like to be safe, not sorry. I worked for a company that began to sell and install business telephone systems. A new system was all digital and had many features. The first company to buy this system had the owner worried about the heat from the ring generator. The manufacturer said it will be...
  4. audioguru2

    0-30V Stabilized Power Supply

    The 1N5402 gets extremely hot at continuous 3A. It cools itself through its leads. Is the copper on your pcb thick enough and is its area large enough? Is the pcb enclosed where it can get hotter and hotter and will heat all the other components?
  5. audioguru2

    0-30V Stabilized Power Supply

    I do not recommend them because they are cooled through their leads which will get VERY HOT. Instead use a bridge rectifier that is bolted to a heatsink like this:
  6. audioguru2

    Simple alarm circuit help!!

    The ICs have no part numbers. Please post the schematic instead of the photo.
  7. audioguru2

    0-30V Stabilized Power Supply

    Heat in a transistor is caused by the voltage across it times the current in it. The result is in Watts. Each of the two output transistors has a voltage across it of 36V and a current of 1.5A when the current from the project is set to 3A and the output voltage is low or is shorted. Then the...
  8. audioguru2

    0-30V Stabilized Power Supply

    The main filter capacitor, R7, the output transistors, the driver transistor and opamp U2 all reduce the maximum output voltage when the project has a load. With a 24V/102VA transformer the improved project will make a maximum of 24VDC at 3A.
  9. audioguru2

    0-30V Stabilized Power Supply

    The original project could not produce 30VDC at 3A and when it was tried, its little 72VA transformer and many other parts were overloaded and they overheated. Maybe its maximum output was 25V at 3A or 20V at 3.75A. The improved project uses a 28V transformer rated at 118VA and many parts are...
  10. audioguru2

    voltage to current source

    I do not know what circuit you are talking about requiring you to convert voltage to current source.
  11. audioguru2

    maximum power transfer

    A speaker resonates which makes it sound bad. Therefore modern amplifiers DO NOT produce maximum power transfer, instead they are a voltage source with an extremely low impedance of 0.04 ohms or less to damp the resonances of a speaker. Look at Damping Factor in Google.
  12. audioguru2

    Remote keyless circuit

    It will contain many very tiny parts and will be difficult to build. Some of the parts might not be sold in small quantities. First you must find a schematic, a parts list and a pcb layout.
  13. audioguru2

    0-30V Stabilized Power Supply

    The circuit you found uses a 7812 voltage regulator so that the original opamps do not have a supply voltage too high. Then opamp U1 will not work unless its circuit is changed to reduce its output voltage. The maximum output from opamp U2 is about +9.5V and the maximum output voltage from the...
  14. audioguru2

    Voltage Monitor

    Are you the guy on the other website who wants to destroy the battery by lighting an LED when the voltage is low and when its load should be disconnected? For an E-cigarette? Doesn't an E-cigarette have an LED that glows when it is used and when the LED gets dimmer and dimmer then does not...
  15. audioguru2

    0-30V Stabilized Power Supply

    I do not know why you cannot buy ordinary parts in your country. An MC34071 quad opamp is in an epoxy package that cannot have a heatsink. You can glue on a heatsink but the epoxy will not conduct heat to it well. The input offset adjustment on opamp U2 sets the output to exactly 0V when the...
  16. audioguru2

    0-30V Stabilized Power Supply

    An MC34074 will probably get too hot. You do not say what is your country. Go to www.farnell.com and click on the flag of your country. They have warehouses all over the world called Element14.
  17. audioguru2

    Need help identifying this part (motu ultralite mk1)

    The original part is tiny and the one you found is huge and might not fit. I recommend finding a short circuit or something that caused the original part to burn, FIRST.
  18. audioguru2

    Very basic questions about capacitors

    A battery voltage remains fairly high as it is used. A capacitor voltage drops quickly at the beginning of powering something then drops less later. So a capacitor cannot be used as a battery unless the current is extremely low. A resistor feeding a capacitor is a filter and it produces a phase...
  19. audioguru2

    abating effect of battery

    A disposable alkaline battery uses a chemical reaction to produce electricity. The chemicals get used up which causes the internal resistance to rise. Then there is a voltage divider with the load resistance. After one year I replace the 9V battery in my smoke detector. The battery voltage...
  20. audioguru2

    Why Circuit not outputting max voltage?

    With the same questions on different forums then it gets confusing because we do not know which forum an answer was given which might be wrong. On the other forum you said the motor draws 3A but you did not say at what supply voltage and if that is its running current or its maximum starting or...
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