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  1. audioguru2

    Which power supply..

    A power supply has a maximum output current which you did not say one word about. How much current do you need?
  2. audioguru2

    0-30V Stabilized Power Supply

    I simply look in the catalog of the parts distributor I buy parts at (I use Digikey or Newark). I don't know which country you are in and I don't know which manufacturers are available in your country.
  3. audioguru2

    0-30V Stabilized Power Supply

    The photo shows Redwire's 5A version of this project. The 0.27 ohm/10W resistor on the pcb is R7 which is 0.47 ohms/10W on the 3A version. 5A x 0.27 ohms= 1.35V. 3A x 0.47 ohms= 1.41V which is almost the same. 5A squared x 0.27 ohms= 6.75W. 3A squared x 0.47 ohms= 4.23W which would make a 5W...
  4. audioguru2

    0-30V Stabilized Power Supply

    The schematic and parts list on the project page has errors and does not work properly. The transformer is supposed to be 28V or 30V at 4.3A (118VA), for 3ADC output, not a 24V transformer. Then the opamps must be higher voltage ones, the TLE2141. The driver transistor is changed and there are...
  5. audioguru2

    0-30V Stabilized Power Supply

    This project gives 30V, not 40V. There is a 5A version. If you make two 0V-30V at 5A projects then you will have up to +30V and up to -30V at 5A. A total of 60V maximum. If you accidently short one supply to the other supply then it will probably blow up.
  6. audioguru2

    0-30V Stabilized Power Supply

    I don't know what you mean by "symmetrical mode". Is it one is a positive supply and a second one is a negative supply? Then build two completely separate supplies and connect the + output of one to ground so its ground connection becomes a negative output. The circuit will need a complete...
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    ON Semi stopped making the MC34071 opamp in a through-holes case.  Digikey and/or Newark might still have some left. It is now only tiny and surface-mount that might get too hot in this project. The TLE2141 is still made in a through holes case. Almost all parts distributors have some.
  8. audioguru2

    0-30V Stabilized Power Supply

    12,000uF/63V was a standard one in Canada when I wrote the parts list. 16,000uF/63V will also be fine.
  9. audioguru2

    0-30V Stabilized Power Supply

    The MC34071 in the through-hole package is not made anymore. Some distributors still have some left. The TLE2141CP is available at the two largest American semiconductor distributors for $1.58 and $1.81 each and they have hundreds in stock. Go to www.farnell.com and click on the flag of your...
  10. audioguru2

    0-30V Stabilized Power Supply

    A voltmeter is connected to the output to show the output voltage. A current meter is connected in series between the output and the load to show the load current. Most digital meters need a power supply that is completely separate from the circuit they are measuring.
  11. audioguru2

    11.1 volts to 8.0 volts ?

    Yes. The voltage must never go higher than 12.60V. An LM317 that has a 120 ohm resistor from its output to its ADJ pin with proper wiring (not a breadboard) is an excellent voltage regulator. When it is set for an output of 12.60V then it can charge a 3-cells Li-Po battery but its current might...
  12. audioguru2

    what kind of amp do i need?

    The parabolic mic will pickup sounds all along the path it is aimed at, including sounds that you don't want.
  13. audioguru2

    0-30V Stabilized Power Supply

    Yes, I agree. If the value of R22 is changed to 1.5k then the current in the LED will be about 19mA which is fine and will be nice and bright. The resistor will dissipate 0.53W so it should be 1W.
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    The original schematic and parts list have many errors. The result does not produce 30V at 3A and is not reliable.
  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    I do not know which schematic you used. R5 in the original schematic and in my modified schematic has nothing to do with current regulation. The opamp for the voltage reference and its zener diode have currents that go through the 0.47 ohm current-sensing resistor. The opamp for current...
  16. audioguru2

    Can Anyone Explain This Circuit?

    The RF power is fairly high and is VERY CLOSE BY. Then an extremely simple AM radio (a crystal radio) will pick it up.
  17. audioguru2

    Can Anyone Explain This Circuit?

    I saw this same question about 1 minute ago on another website. The spark makes fairly powerful local RF energy. A simple AM radio circuit (maybe a simple crystal radio) picks it up and flashes the LEDs.
  18. audioguru2

    11.1 volts to 8.0 volts ?

    The LM317 is supposed to have a 120 ohm resistor from its output to its ADJ pin so that its output voltage does not rise when there is no load. Then the value of the pot should also be reduced to half. The datasheet shows that the more expensive LM117 can use 240 ohms. The datasheet explains...
  19. audioguru2

    0-30V Stabilized Power Supply

  20. audioguru2

    0-30V Stabilized Power Supply

    I have posted the corrected and updated schematic and parts list hundreds of times. It is too bad that the original project is wrong and does not show my corrections. It produces regulated 0V to 30V with regulated current from a few mA to 3.0A. Since you want only a small voltage and current...
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