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  1. audioguru2

    Need to design a filter to allow only voice frequencies

    The circuit posed by me will work fine when both opamps are fed from the half-supply generator.
  2. audioguru2

    LM567

    Hi Dan, Welcome to our forum. ;D We have an electronic Keys Finder project in our Projects Section: http://www.electronics-lab.com/projects/misc/002/index.html It uses the same piezo transducer for the microphone and beeper. I don't know if anybody made it work, and it might not be possible to...
  3. audioguru2

    Need to design a filter to allow only voice frequencies

    Hi Sundar, The Multiple Feedback Bandpass Filter circuit you posted passes a very narrow range of frequencies. "Telephone Quality" voice frequencies are from 300Hz to 3kHz. You need a highpass filter to reject frequencies lower than 300Hz followed by a lowpass filter to reject frequencies higher...
  4. audioguru2

    amplifier help

    Hi Pier, Attach your schematic with the mic and volume control wires shown. Did you make the circuit in the datasheet? Did you use an electret mic type? Is it powered correctly?
  5. audioguru2

    labels on electronics

    Most electronic parts have datasheets published by the manufacturer. They give max voltage, current and power ratings and detailed operating spec's. Frequently a typical circuit and pcb pattern is shown. Some datasheets are found on Google but mixed with people selling parts. I get most...
  6. audioguru2

    Electronics World Magazine

    Hi Ante, I don't have a scanner and haven't opened the printer that came with my 2-years-old pc. I'll try taking pics with my new digital camera.
  7. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    I was explaining that paralleled capacitors also work well and are needed at RF frequencies. A low-value capacitor is an excellent low-inductance bypass for high frequencies. A higher-value capacitor is inductive so is a poor high frequency bypass but is good at lower frequencies. Both in...
  8. audioguru2

    Low-pass Filter?

    A 4047 is made by most semiconductor IC manufacturers. Their prefix isn't all "CA". Motorola (now called ON Semi) call theirs an MC14047B. All newer ones have "B" as a suffix which means the outputs are buffered. Some manufacturers use uA as a prefix and call it a uA4047B. Texas Instruments used...
  9. audioguru2

    Convert 0-30V 3A PSU to 5A or more

  10. audioguru2

    DIODE QUERY

    The amount of capacitance of a diode is very small. The leakage current of a diode or surrounding circuitry would discharge its capacitance almost immediately.
  11. audioguru2

    TDA1524A Tone Control IC

    What is "a Piezo Type Stereo tuner"? Tuners don't use piezo. Quartz crystal maybe?
  12. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    I think that smaller-value capacitors in parallel will work exactly the same as a single capacitor with the total of their values, except they will cost more and use more space. At VHF radio frequencies and higher it will make a difference due to the inductance of a larger capacitor.
  13. audioguru2

    DC voltage regulator

    12V - 5V= 7V. 7V x 700mA= 4.9W. A fairly small heatsink is needed with a TO-220 package for only 4.9W. When the car is running then its votage could be 14.4V. Then the regulator will dissipate 6.6W. The heatsink can be much smaller if you don't use an insulator. Then insulate the heatsink from...
  14. audioguru2

    TDA1524A Tone Control IC

    Hi WildSwan, Nearly all volume controls are logarithmic, also called "audio taper" to match the logarithmic sensistivity of our hearing to loudness. If a linerar pot is used instead then the output will be near max for most of the rotation then a sharp drop when the pot is turned to nearly zero...
  15. audioguru2

    Adding auxiliary input.

    Just add a 2-pole switch and two jacks. The switch will disconnect one of the internal functions and connect the jacks as inputs instead.
  16. audioguru2

    DC voltage regulator

    In my part of the world, a 7805 regulator is in a TO-220 package and many heatsinks are available for them. A TO-3 package is used for very high power and large heatsinks are available, few small ones.
  17. audioguru2

    Electronics World Magazine

    I have many Electronics World magazines from the 70's and 80's when John Lindsey Hood made some good analog circuits.
  18. audioguru2

    DIODE QUERY

    A diode is not a battery. It has a small capacitance that will hold a charge until leakage discharges it.
  19. audioguru2

    Some angel out there!! need help for motor speed control by pll

    Hi Kellie, Your schematic still shows pin2 and pin5 of the LM565 backwards and output pin4 shorted to ground. Pin4 is the VCO output of the LM565. Your encoder's output is the VCO output of your circuit so don't connect pin4 to anything. Maybe the DC voltage on pin2 and pin5 are not correct...
  20. audioguru2

    Signal Detector help

    Hi Jaime, Welcome to our forum. ;D A comparator is not a radio receiver. You need a radio receiver to receive a signal from the alarm's transmitter. The transmitter transmits a radio signal, not sound. Then the presence of the alarm sound from the radio receiver can activate the vibrator.
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