Search results

  1. audioguru2

    dc power supply

    4VAC is rectified and filtered into 4.3VDC. An LM317 adjustable voltage or current regulator needs an input of at least 2VDC higher than its output for a voltage regulator and at least 3.3VDC higher than its output for a current regulator. You forgot to say which type of battery. For 2V then it...
  2. audioguru2

    telephone transmitter again not working??

    The pins layout on European transistors like the BC547 are reversed from American transistors like all the ones shown. 5.6pF is a standard value. 5.8pF is not. The circuit will work with a capacitor value from 4.7pF to 10pF.
  3. audioguru2

    Commodore 64 repairing gone forgotten?

    I liked the Quad electrostatic speakers in the "good old days". I shopped for speakers that sounded almost the same and selected less expensive Acoustic Reasearch speakers. Then all the speakers I made are adjusted to also sound similar.
  4. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Thomas, Your project looks neat, tidy, compact and very nice. I am glad to hear that it works perfectly. ;D
  5. audioguru2

    Electronic Eavesdropping Devices Detector

    Use the pcb that is shown in the project.
  6. audioguru2

    TDA2005 making static noise

    I guess the TDA2005 is sensitive to radio signals.
  7. audioguru2

    Need Someone to Build This

    Does this project work? The IR diodes are forward biased which causes the connected gates to always have a high input level. iR diodes should be reversed biased to generate leakage current or should have no bias to generate a small voltage. Where can you get 200MHz and 400MHz crystals? The max...
  8. audioguru2

    Sound Level Indicator

    Didn't you use a special MC33172 dual opamp? R7 grounds its input so the output at the emitter of Q2 which connects to pin 5 of the LM3915 should also be ground. It will oscillate if the 9V battery is low. Didn't you use a special LM2931AZ-5.0 regulator? Everything connected to +9V on the...
  9. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi AN920, Digikey don't have any MJE180 transistors, maybe because it is old and is hardly used anymore. It might become obsolete soon. I haven't seen transistors with that old Motorola case since the '60s.
  10. audioguru2

    TDA2005 making static noise

    Hi Wellington, Your circuit has too many resistors, too many capacitors, too many opamps and too much gain. Unfortunately, the TDA2005 needs to have a minimum gain of 32dB so it amplifies the noise from the opamps. Maybe the useless R68 can be made an attenuator. I have modified only the...
  11. audioguru2

    Sound Level Indicator

    Again, without a sound, measure and post the DC voltages at pin 5 and at pin 6 of the LM3915. Pin 5 should be 0V and pin 6 should be about 0.5V. Pin 5 is the input. Pin 6 sets the input voltage that will light all LEDs: With 0V input then no LED will light. With 0.022V then the first LED will...
  12. audioguru2

    Question about triggering transistors

    Electricity current flows only when there is a source wire and a return wire. Frequently two power supplies are used and their returns are connected together.
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi aN920, You are talking about high frequency changes in load current. Or quick changes in load current. I think that C9 rolls off the response so that the overall gain is only 2 at 89kHz. Then C6 straightens out the phase response.
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    It is amazing that the kit maker uses a little 2N2219 that has a very low power dissipation. With only 32V across it then it is at its max power dissipation (with a heatsink) with a current of only 56mA. Then the 2N3055 transistor needs to have a current gain of 54. The minimum gain of a 2N3055...
  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    Since a higher value for the lead capacitor C6 causes ringing, then additionally using a higher value for the lag capacitor C9 should reduce the ringing. But then the output voltage will have a glitch when the load current is changed. 
  16. audioguru2

    Your next lawn mover!

    Yeah. Use the monster V-12 super-charged engine from a Lancaster bomber on a lawnmower.
  17. audioguru2

    Commodore 64 repairing gone forgotten?

    I was very young when i made my first vacuum tubes amplifier.
  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    I think the lead-compensation capacitor C6 sould have its value increased when the driver trransistor is a slow TIP31A. Now it is only 100pf which is nearly nothing.
  19. audioguru2

    0-30 Vdc Stabilized Power Supply

    A 741A opamp has a 44V supply rating.
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    They are both good for this circuit. Use either one.
Top