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  1. Audioguru

    Distortion Pedal Redux

    DO NOT connect the + input of the used opamp to the 1M resistor, instead connect it to the two 100k or two 10k voltage divider resistors and the capacitor to ground that is there.
  2. Audioguru

    Distortion Pedal Redux

    The video has a very simple ordinary opamp circuit with a gain adjustment to produce a gain of 1 up to a gain of 501, soft clipping diodes, no bass (727Hz is at -3dB and lower frequencies at -6dB per octave) and reduced highs. At 7:50 he talks about using a larger capacitor (that I recommended)...
  3. Audioguru

    Horrible TV Audio and Video Lately

    The voices fade from almost normal to sounding like a chipmunk with no low frequencies then fading back to almost normal and back to chipmunk while they are talking. My video phone calls on Facebook Messenger dont doo dat.
  4. Audioguru

    Distortion Pedal Redux

    Please describe the noise. Low frequency hum (from nearby electricity wiring), high frequency hiss, or audio from every radio and TV station and police and ambulance communications in town. Those are noise descriptions. A say additional noises are electric guitar overdrive, acid rock and RAP. Oh...
  5. Audioguru

    Distortion Pedal Redux

    Does the opamp circuit work without the diodes? With its gain of 221 times then its output will have very loud severe clipping distortion. Adding the diodes reduces the distorted level a lot and the distortion sounds different to the opamp clipping.
  6. Audioguru

    Horrible TV Audio and Video Lately

    Reporters and government people are frequently at home lately and are shown on TV with the audio sounding awful (low frequencies are frequently missing) and with poor lip-sync to the video. The video is chopped up or frequently freezes. Is it a SKYPE program that causes these problems? Is there...
  7. Audioguru

    Distortion Pedal Redux

    The voltage divider has only 3 resistors and 2 or 3 capacitors so why can't it be near the opamp's pin 3? Your builds always had a correct voltage on pin 3. The diodes should be connected directly to pin 2 with a short distance to pin 6. A shielded cable from the diodes to a switch to turn them...
  8. Audioguru

    Distortion Pedal Redux

    Modules for the simple opamp circuit will cause interference: The 1M resistor and input of the opamp have very high input resistances that will pickup electricity 60Hz and all kinds of other interference unless careful shielding is used. The shielding will probably kill high audio frequencies...
  9. Audioguru

    4017 Different LED count

    Like above, a "Road Runner" circuit uses diodes to steer the outputs of a CD4017 to make a row of LEDs light back and forth.
  10. Audioguru

    Distortion Pedal Redux

    Some 741 opamps do not work when the supply voltage is less than 10V. and some have an input resistance that is too low for this circuit. A TL081 opamp has a 7V minimum supply and has an extremely high input resistance like an old vacuum tube. Without the opamp in its socket, only pin 7 (9V...
  11. Audioguru

    Distortion Pedal Redux

    The circuit will not work when the resistor (220k) between pin 2 and pin 6 is missing. Is the resistor connected? Where did you buy a fake TL081? An Oriental 10nF green cap is marked 103.
  12. Audioguru

    Distortion Pedal Redux

    Nothing should be crammed, instead the parts should be fairly close together and wired together as shown on the schematic. No, the diodes are back-to-back in parallel and in parallel with the 100pf capacitor and in parallel with the 220k. They are all connected between pin 2 and pin 6. None of...
  13. Audioguru

    Distortion Pedal Redux

    I have never seen a 100pF film capacitor, just ceramic at radio frequencies and low impedances. Use it. Parallel to the 220k resistor, 7.3kHz and higher frequencies will be reduced.
  14. Audioguru

    Distortion Pedal Redux

    4.5V at pin 3 is correct. The back-to-back diodes and 100pF ceramic capacitor are in parallel with the 220k resistor and connect to pin 2 and pin 6 of the opamp. The 10nF input capacitor is film and the larger capacitors are electrolytic.
  15. Audioguru

    Amplifying speaker without amp or power supply

    EDIT: Lookup MC34018 speakerphone IC. It was used 37 years ago to produce 0.1W into a 25 ohm speaker when powered from a phone line. A newer IC was made a couple of years later.
  16. Audioguru

    Amplifying speaker without amp or power supply

    A phone system was designed and used 143 years ago to use an old fashioned carbon mic that draws about 15mA and the wiring was 600 ohms. No loudspeaker and no amplifier. 600 ohms x 15mA needs 9V. If you use an amplifier that is powered from 9V from a phone line and uses only 15mA then the power...
  17. Audioguru

    Distortion Pedal Redux

    I marked up notes on a previous schematic about your wrong capacitor values. This schematic uses different resistor values but your resistors are fine.
  18. Audioguru

    Distortion Pedal Redux

    What fixed your opamp circuit?
  19. Audioguru

    Distortion Pedal Redux

    For a TL081 opamp: Pin 1 and pin 5 should have almost the same low voltage. Pin 8 should not have a voltage. Pin 6 output should have the same voltage as pin 3 input. It might not be an opamp. Where did you buy it?
  20. Audioguru

    Solar Diode

    Without a series current-limiting resistor, on a sunny day the battery might explode. Energizer battery company says that a Ni-MH battery must not be trickle charged (the charger must detect a full charge then shut off).
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