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  1. audioguru2

    Re: Automatic AC generator

    I think he lives on a distant planet where the electricity fails all the time. Then he wants the generator to automatically start and supply electricity. The generator must stop when the electricity resumes.
  2. audioguru2

    0-30 Vdc Stabilized Power Supply

    The final schematic has the value of the calibration trimpots. It is a PNG file type, not a PDF. It is this one:
  3. audioguru2

    powering on and off

    No. Use Name Brand parts and stay Well Within the spec's. To power a 100W load then use a part that is rated to power a 150W load. Then it will probably last forever (but it might cost a little more).
  4. audioguru2

    0-30 Vdc Stabilized Power Supply

    Your transformer's voltage is too low. A different opamp cannot boost the transformer's voltage. DO NOT make the first version of this project because it has a lot of problems in addition to these problems.
  5. audioguru2

    0-30 Vdc Stabilized Power Supply

    No. The peak voltage of the 24VAC transformer is 33.9V and the rectifiers drop it to 31.9V. The main filter capacitor has ripple that reduces the unregulated positive supply to +29VDC. At 3A, R7 has a voltage drop of 1.41V, the 2N3055 transistors and their emitter resistors have a voltage drop...
  6. audioguru2

    Dual Voltage Power Supply Help

    The original circuit does not work. The transformer's voltages are too low. The 18V center-tapped transformer has peak voltages of plus and minus 12.7V. The rectifier drops it to 12V and the ripple in the main filter capacitor drops it to only 11V at a 1A load. Then the 12V regulators and your...
  7. audioguru2

    Need Help Buiding the project using lm386

    The value of the 22 ohm resistor R3 is wrong and the value of the 0.22uF capacitor C7 is also wrong. Look at the correct circuit in the datasheet of the LM386.
  8. audioguru2

    Need Help Buiding the project using lm386

    Why didn't you post the schematic or link to it? It is this project: http://www.electronics-lab.com/projects/audio/044/index.html The datasheet for the LM386 shows how to connect it. It does not use a 22 ohm resistor and it does not use a 0.22uF capacitor. It is supposed to be 10 ohms with a...
  9. audioguru2

    0-30 Vdc Stabilized Power Supply

    The MC34071 and TLE2141 opamps have inputs that work at the negative supply voltage and have outputs that go down to the negative supply voltage. Most opamps including the NE5534 have inputs that do not work if they are 2V or less away from the negative supply voltage and have outputs that go...
  10. audioguru2

    0-30 Vdc Stabilized Power Supply

    One of the  numbers is wrong. 30VAC at 230VA is a current of 7.67A, not just 3.83A which is too small. The transformer must be rated for 130VA or 4.3A. The 30V/130VA/4.3A recommended transformer has a voltage of 31V without a load. Then its peak voltage is 43.8V and the rectifiers (yours are way...
  11. audioguru2

    powering on and off

    I have always used name-brand parts. They have max spec's. I design circuits well within the spec's of the parts. I have designed and assembled hundreds or thousands of circuits and none failed. I designed some products where tens of thousands were made and sold. Two failed in quality control...
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    Measure the output voltage with the voltage setting pot turned down and adjust the input offset adjustment trimmer on U2 for exactly 0V. Measure the output voltage with the voltage setting pot turned up and adjust the gain trimpot for U2 for exactly +30.0V. Connect a load for more than 3.0A...
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    One trimmer adjusts for exactly 0V. One trimmer adjusts for exactly +30.0V. One trimmer adjusts for exactly 3.0A.
  14. audioguru2

    Battery Charging - Help?

    I charge 2200mAh Lithium-Ion two-series-cells batteries with a 9V/500mA wall-wart to limit the current to about 500mA and an LM317 voltage regulator set to exactly 8.4V. The wall-wart and LM317 get pretty warm at first then get cold as the battery reaches full charge. The battery does not get...
  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    With a 20,000uf capacitor you should use a 10A rectifier bridge module. The circuit will overload your transformer because its max current will be about 4.1A. Use 1 ohm for R7 for about 2A max. Many of the resistors in the original project got too hot. You will need to calculate the dissipation...
  16. audioguru2

    0-30 Vdc Stabilized Power Supply

    The main filter capacitor should be about 10,000uf. R10 must connect to the negative supply, not to 0V. R14 should be 1.8k with your 22VAC transformer. One 2N3055 transistor could be used if it has a pretty big heatsink. With two 2N3055 transistors the circuit will supply 20V at 2A perfectly.
  17. audioguru2

    0-30 Vdc Stabilized Power Supply

    The latest modifications use easy-to-find MC34071 or TLE2141 opamps that have inputs and outputs that work at 0V with a single polarity supply. Their max allowed supply is 44V. But a low voltage negative supply is needed because the output of U3 must go negative enough (about -0.7V) to allow D9...
  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    Like the original project, the values for R4 and R10 are wrong and R10 connects to the wrong voltage. Also like the original project, the main filter capacitors are much too small. Each 2N3055 output transistor needs a series emitter resistor for matching. The value of R14 will need to be...
  19. audioguru2

    What the value of Zout???

    If you use an output transformer to increase the load impedance then it steps down the signal voltage. An emitter-follower transistor will increase the load impedance without the signal voltage loss.
  20. audioguru2

    What the value of Zout???

    A 100k load is a high impedance to the LC parallel tuned circuit and will be fine. A 1k load would be much too low.
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