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  1. audioguru2

    0-30V Stabilized Power Supply

    Of course not! Its max output current is only 3A. The transformer is at its limit when the output current of the project is 3A. The output transistors and driver transistor (and maybe opamp U2) are also at their limit when the output is 3A. We have a thread about increasing the output current...
  2. audioguru2

    0-30V Stabilized Power Supply

    With the 24V transformer, the max output voltage from this project is only about 25VDC. The 1000VA transformer will only partially be used since at 24V AC only 102VA is needed. It is expensive, big and heavy.
  3. audioguru2

    0-30V Stabilized Power Supply

    A 150VA transformer will be fine but is more expensive and is heavier.
  4. audioguru2

    DC Power Supply (5V 10A) - Questions

    Since a switching power supply is mass produced it is very common and very inexpensive. So I have never built one.
  5. audioguru2

    DC Power Supply (5V 10A) - Questions

    The 12V transformer has a peak voltage of 1.414 x 12= 17V. The rectifiers operate at the 17V. The max continuous power from the transformer is 72VA so the max continuous DC current from this power supply is 72/17= 4.2A. 17V is much too high for a 5V supply because the extra 12V simply wastes...
  6. audioguru2

    Project (Simple Stereo Audio Amplifier)

    A lousy old LM358 is low power so its output operates in class-B to save power instead of in class-AB like all other opamps. Therefore it has horrible crossover distortion. It also has trouble above only 2kHz. It is not a low noise opamp so of course it produces a lot of noise when the gain is...
  7. audioguru2

    0-30V Stabilized Power Supply

    Hi Andreas. It is too bad that the power supply kit posted in the original project was very poorly designed. We have made a few modifications over the years to fix it and I have posted the latest parts list and schematic millions of times. Here they are again:
  8. audioguru2

    0-30V Stabilized Power Supply

    Look at www.farnell.com to see that they supply modern electronic parts in your country.
  9. audioguru2

    0-30V Stabilized Power Supply

    A 120VA transformer is slightly too small. Then when the project is supplying 3A continuously the transformer will be slightly warmer than its max allowed temperature. Inside a box it might get too hot.
  10. audioguru2

    0-30V Stabilized Power Supply

    With 27V on the output opamp then the max output of the project will be only about 21V, not 30V. You would have the same 21V max output if you used a 21V transformer. Then only a single 2N3055 output transistor is needed and the driver transistor will be cooler. Why not use the newer 44V opamps...
  11. audioguru2

    1.2-15V 3A Adjustable regulated power supply

    Your 18.5V (x2) transformer has a voltage that is too high and it produces +25V at the input of the IC regulator. If the circuit has the pot turned down so the output voltage is 6V then the IC must try to dissipate 57W when the current is 3A which will cause it to overheat and shutdown. The IC...
  12. audioguru2

    1.2-15V 3A Adjustable regulated power supply

    With an unregulated input to the IC of 18VDC and an output of 1.2V at 3A then the IC dissipates 50.4W. If its heatsink is infinite and perfect then the chip's temperature is about 175 degrees C (well over its max allowed temperature of 125 degrees C). But its little heatsink is good for only...
  13. audioguru2

    How to switch 3A with a mircoswitch?

    Your "4.2V" battery will be only 3.0V when it needs to be re-charged. The datasheet does not list the voltage lost when the gate-source is only 3V but a graph shows that a "typical" IRL540 Mosfet will have a loss of only 0.2V at 3A. A "minimum" one might have a loss of 1V or more. Where can you...
  14. audioguru2

    0-30V Stabilized Power Supply

    Yes that is the correct IC. The E-Bay seller is in my country and sells it at almost double its normal cost here. I don't know how much the shipping will cost to your far away country.
  15. audioguru2

    How to switch 3A with a mircoswitch?

    A "logic level" Mosfet switches very well when its gate is 4.5V or more. Very few Mosfets switch well when their gate is only 3.7V.
  16. audioguru2

    Help for a school Physic Projet ''Bulding a FM transmitter ''

    A high quality and very sensitive FM receiver is very complicated with many parts that are almost impossible to buy unless you buy a high quality receiver and take it apart to re-use its parts. An extremely poor quality FM radio costs $1.00 at The dollar Store. It uses a Chinese copy of an...
  17. audioguru2

    Ultrasound Proximity Sensor for Blind??? Please help

    There are many articles and projects in Google. What is the jibberish? It is a simple reflection of ultrasound and detecting the delay and calculating the distance.
  18. audioguru2

    Help for a school Physic Projet ''Bulding a FM transmitter ''

    If the volume from the music source is turned up too high then the FM transmitter swings its frequency too wide and causes severe distortion in an FM radio. The maximum deviation from an FM radio station a full volume is +/- 0.075MHz. Turn down the volume so the transmitted signal heard on the...
  19. audioguru2

    0-30V Stabilized Power Supply

    The "must operate" voltage of a relay is the maximum coil voltage to activate it. Its maximum must operate voltage is 42V and its minimum might be only 30V or less. Its "dropout" voltage is a minimum of 10% of its nominal 60V rating which is only 6V. So it is useless to detect when the supply...
  20. audioguru2

    0-30V Stabilized Power Supply

    2x15VAC is fine (30VAC) if it is rated for 126VA or more or 4.2A AC or more. With a 24VAC/102VA transformer the max output from the project is about + 25VDC at 3A.
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