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  1. audioguru2

    Need sugestions about virtual ground or symetric supply for OPAMP

    Hi Wellington, The "music" is rap which is talking to a beat. No music. I didn't hear any cracking up. The signals before R2 and before R25 are the input signals. They should be clean. The signal after R2 is attenuated R channel and extremely low level distortion from the L channel. Your...
  2. audioguru2

    Are datasheets important?

    I did so complete my engineering course. I have my degree. I did not have a mentor so I could not complete the internship required for me to be registered as a professional engineer in Canada. I was too busy designing circuits and improving existing ones. In my carreer I performed the job of...
  3. audioguru2

    CATV Signal Amlifire

    It is made to amplify only one or two channels. Many channels cause intermodulation because it is too simple. It has too much distortion and too much gain for a CATV amplifier. Ask your cable TV company to fix your cable so it works properly. My cable broke in winter when they couldn't dig to...
  4. audioguru2

    3mm Jack Audio switcher

    You need a double-pole double throw switch (DPDT). It selects one stereo signal from two stereo signals. I use switches with gold plated contacts for switching audio signals. The gold costs only slightly more and is much more reliable than high current silver contacts that tarnish then don't...
  5. audioguru2

    Electronic Eavesdropping Devices Detector

    With no radio signal picked up by the circuit, the output pin 1 of opamp A1 is supposed to be 0V so the voltage-controlled-oscillator that is made with the other opamps has no sound output. Your A1 opamp amplifies its own input offset voltage and makes its output voltage high enough for the...
  6. audioguru2

    Need sugestions about virtual ground or symetric supply for OPAMP

    I made my SQ full logic surround sound decoder with the inexpensive ICs from Motorola. With ordinary stereo signals the surround effect was weird because it  frequently caused sounds to go around the room randomly.
  7. audioguru2

    Are datasheets important?

    I saw the author's photograph in Google. He looks "unusual". He is a research engineer for satellite communications at a university in Singapore. He made many mistakes with this inverter project: 1) The wiring for the CD4047 IC shorted the power supply. 2) The CD4047 had the wrong value...
  8. audioguru2

    TLO74 ??? Dynamic Mic./Cond.Mic. amplifier.

    A TL074 is not the best quad opamp for high gain but it will be OK for an old cassette head amplifier and as an amplifier for its microphone. Tape heads have a playback equalization that boosts the low frequencies. I don't know if the equalization standard is on the web because cassette tape...
  9. audioguru2

    Need sugestions about virtual ground or symetric supply for OPAMP

    My Halfler surround sound was passive and used no electronics. The rear speakers were wired in series and were powered from the HOT terminals of the left and right amplifiers. So the rear speakers played the ambience difference sounds between the channels and the main speakers played the...
  10. audioguru2

    white led

    Nice lenses.
  11. audioguru2

    help in ultrasonic

    I don't know how much power your piezo ultrasonic transducer needs. I don't know if it works as high as 50kHz.
  12. audioguru2

    Need sugestions about virtual ground or symetric supply for OPAMP

    It sounds good now. How do you like the Hafler surround sound effect?
  13. audioguru2

    help in ultrasonic

    You don't need high output power to drive a little piezo transducer. You just need a little power amplifier that uses transistors.
  14. audioguru2

    help in ultrasonic

    Use a power amplifier that has transistors to amplify the 50kHz. Use filtered DC to power it. Your thyristor turns on and stays on for each pulse of 100Hz. It is not amplifying the 50kHz.
  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    The 24VAC transformer has a peak of 34V which is dropped to 32VDC by the rectifier bridge. The tiny 3300uF main filter capacitor will create a peak ripple voltage of 2V so the lowest part of the unregulated supply is 30VDC when the load current is 3A. The opamp U2 has a max output voltage of...
  16. audioguru2

    Need sugestions about virtual ground or symetric supply for OPAMP

    Hi Wellington, The junction of the two resistors at the input of the virtual ground opamp is a filtered voltage divider of the supply voltage. Maybe your supply voltage is fluctuating?
  17. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Omni, Does your power supply project provide 30VDC/3A with low ripple? Does it provide 5V/3A without its transformer, 2N3055 transistor and 2N2219 transistor burning up?
  18. audioguru2

    Need sugestions about virtual ground or symetric supply for OPAMP

    The 0.1uF filter capacitor in the Analog Devices phantom ground circuit is much too low. They use a 110k resistor for their opamp but it isn't needed with the FET inputs of a TL072 opamp. Use the Virtual Ground circuit I posted.
  19. audioguru2

    Two PCBs off of one power source

    A silicon diode has about 0.7V across it. So four in series from 6V produces 3.2V. When the battery voltage drops to 4V then the output from the diodes will be only 1.2V.
  20. audioguru2

    Need sugestions about virtual ground or symetric supply for OPAMP

    The very low output resistance of my virtual ground opamp feeds all the bias resistors for the circuit. That was Elvis Presley? From 1955 when they had recording equipment with severe distortion? No wonder I heard the distortion. The 22nF capacitors overload the output of the opamps if the...
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