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Led synchronization circuit

Discussion in 'LEDs and Optoelectronics' started by Nitesh pingale, Jan 31, 2018.

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  1. Nitesh pingale

    Nitesh pingale

    Jan 31, 2018
    How do i run this circuit on 5v power supply??(its 9v)

    Attached Files:

  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Just give it a try. If the LEDs are too dim, reduce R4...R7 from 1 kΩ to 475 Ω.
  3. Nitesh pingale

    Nitesh pingale

    Jan 31, 2018
    ok i will try
  4. Audioguru


    Sep 24, 2016
    The circuit is designed wrong:
    1) Its battery is missing a supply bypass capacitor to keep the voltage up when all the LEDs turn on.
    2) The circuit is missing a resistor and filter capacitor to feed the 10k resistor that powers the mic which will probably result in motorboating oscillation.
    3) Transistor Q1 is NEVER biased like that when it is a linear audio amplifier but since R2 has 8.4V across it and the value of R3 is as high as 10k then Q1 is turned on most of the time which turns off the LEDs then sounds turn on Q1 and the LEDs.

    If the circuit is powered from 5V then R2 has a voltage of 4.4V and a current of 4.4uA. If Q1 has a low hFE of 100 then its collector current will be 440uA causing the transistor to be properly saturated. A higher hFE will cause more saturation which will be fine.
    No problem using 5V power except the LEDs will be dim, reduce R4 to R7 to 470 ohms as above.
  5. Nitesh pingale

    Nitesh pingale

    Jan 31, 2018
    Ok thnx
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