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  1. audioguru2

    10w mini amp questions.

    Hi Nick, The wiper of a pot wipes from one end of its resistance to the other end.
  2. audioguru2

    10w mini amp questions.

    It doesn't use and there is no such thing as a 450nF cap. It needs 470nF for C3. The project's layout sketch correctly shows the wiper of the pot connected to C3, and the ends of the pot connected to the input and to ground.
  3. audioguru2

    HELP NEEDED

    You have two frequencies there. A high frequency with a few quickly fading cycles and a lower frequency repetition rate. A Phase-Locked-Loop IC could lock onto the high frequency if its repetition continues, and an AM detector could clean-up the repetition frequency.
  4. audioguru2

    Stereo Audio power amplifier 2 x 40W - 80W

    That will work.
  5. audioguru2

    Another INVERTER we can talk about..

    Here is their most powerful class-D outut stage. Believe it or not it is tiny and is surface mount:
  6. audioguru2

    Stereo Audio power amplifier 2 x 40W - 80W

    Yes. The output of the preamp also goes to the input of the tone controls section. No. The output of the peak detector circuit feeds the SIG input of the LM3915. The LM3915 and LEDs are powered from 12VDC. Changing the ratio of R3 and R4 to change the sensitivity also changes the brightness. Use...
  7. audioguru2

    Another INVERTER we can talk about..

    I don't think the LM4651 is still being made. The National site says, "Lifetime Buy" instead of "Full Production". A couple years ago I was going to design a pure sine-wave inverter using it when I found out it was being cancelled. Texas Instruments and other semiconductor manufacturers make...
  8. audioguru2

    Stereo Audio power amplifier 2 x 40W - 80W

    The output of the peak detector circuit is not audio, it is a fluctuating DC voltage for the display. Therefore the preamp feeds it and feeds the tone controls section, then the volume control takes the output of the tone controls section to feed the power amp. The peak detector opamp needs...
  9. audioguru2

    Stereo Audio power amplifier 2 x 40W - 80W

    The bass/treble circuit will work fine. The diodes at the front of the LM3915 are not needed and will short the output of the preamp. Use the Half-wave Peak Detector circuit in the datasheet instead.
  10. audioguru2

    Dual Transformer Power Supply

    Elliot Sound Products has 17 power supply projects. Which one?? Why are you using two transformers instead of one? What is wrong?
  11. audioguru2

    Low powered FM transmitter

    Hi, The antenna length for an FM transmitter is reasonable because it operates at the very high frequency of about 100MHz. AM radios operate at a frequency 100 times lower so a transmitting antenna should be 100 times longer. A very high frequency transmitter needs to be made with very short...
  12. audioguru2

    Stereo Audio power amplifier 2 x 40W - 80W

    The opamp for the bass and treble control is shown DC biased for positive and negative supplies. You can add a voltage divider and bypass cap to pin 3 then use the same single positive supply as your preamp. Add an input coupling capacitor or use the output coupling capacitor from the preamp...
  13. audioguru2

    Electronic Stethoscope

    Store the BPM number in a memory chip.
  14. audioguru2

    Electronic Stethoscope

    Hi Evix, You want to store the BPM number, not record all the pulses of heatbeats.
  15. audioguru2

    Sound electronic activated switch

    The kit that you posted does that with two sounds. Two hand claps, two dog barks, two firecrackers.
  16. audioguru2

    What are Heat Sinks??

    Here is a pic of a power transistor (shiny silver color) bolted to a cast aluminum heatsink (black with many fins for high surface area) with a mica insulator between (white color). This is from the power supply in our Projects Section.
  17. audioguru2

    Simple O2 meter with LM3915

    Hi Wellington, This is much better. ;D R9 is not needed. Check the datasheet's explanation about cascading LM3914's and add a resistor across LED #9 and a resistor across LED #11.
  18. audioguru2

    High screech sound over telephone?

    I answered you already. Nobody ever wanted to make noises on a phone line. You could make a circuit to connect a tone to a phone line but it won't be very loud because the phone system and phone at the other end limits the volume. It won't be a harsh high tone because a phone line doesn't pass...
  19. audioguru2

    Sound electronic activated switch

    Two claps will turn it on. Then two more claps will turn it off. Two claps will turn it on again, etc. Is that what you want?
  20. audioguru2

    please, schematic of AM Demodulator

    An AM demodulator is a very simple circuit. It is also very simple to find out about these things by looking in www.google.com .
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