audio limiter compressor circuit schematic

Audio Limiter Circuit

This audio limiter circuit is easy to build, works with BA741 8pins or 4pins so pay attention and uses a symmetrical power supply. When the audio input level is between 20mV and 20V the output will be a constant 25mV signal. Audio limiters can be used in a transmitter schematic or in any circuit you need a constant audio level.

Audio limiter circuit schematic

audio limiter compressor circuit schematic

Audio limiter components
R1 = 100K
R2 = 1K
R3 = 1M
R4 = 68K
R5 = 10K
C1 = 10uF
C2 = 680nF
T1 = BFW11
T2 = BC173C
IC = BA741


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  • mirceacluj

    ist good for TV advertisements ???

  • raju

    pls will u suggest me any mini project on audio limitter and electronics basis project rply me as soon as possible

  • Serge

    Hello! I wanna know where do you place your Audio Limiter in the circuit? I want to put that in te Motorola CB radio. Can I put this limiter between radio and speaker or another place?

  • milesrhart

    So what is a BA741? An OP amp?
    And does it have the same specs as an LM741?

  • sandiz

    can you give corrected, working schematic?

  • tbk

    can you help me. I want to output 3V when input is 2-10V.
    how to calculate circuit ?

  • James

    Realmente não funciona como deveria pois terá um má ou não funcionamento correto do transistor T2, sendo que R3 está polarizando o coletor de T2 como uma tensão negativa em relação ao terra que esta no emissor do mesmo, neste caso é como o terra fosse positivo na polarização do transistor…. deveria ser um PNP (ex.:BC559 OU EQUIVALENTE)

  • electro

    Transistor T2 can not be NPN because have in the collector -15Vcc. Not polarized properly. And t2 the need of resistance in base.
    So, the circuit limited only one alternating audio signal; Not exactly pleasant!!!!!!!!!!!1

    • romi

      The input has to be pulled up (polarized) at 5V for example so the music signal swings around 5V and not around 0V. This way both positive and negative sides of the input signal are attenuated.

    • Jeff

      Can you please send me your contact info ? I need someone with your knowledge to help design a new product. Thanks .. U.S. Miami, Florida 33141


      You are so good! Yes, is not pleasant to hear that only one audio signal is alternating… I wonder why? And why the NPN transistor in NPN and not PNP… this is so strange, you genius! R5 is not in the base of T2?

  • Sg

    And I think, something is wrong… Because the ic 741 has just 8pins. On the schematic is 11pins:S

    • Arat

      The + noninverting input should be to Pin 5 & NOT 8 as shown in the schematic! Pin 8 is NC- has no connection- in 14 pin PDIP 741 devices! So why not use an 8 pin 741 instead? This is more readily available than the 14 pin device & will take less space!

    • Sg

      (Sorry: are 11pins:))

  • Sg

    I think, all J-fet op.amp. are equivalent:)
    Just the sound will be better…
    And you will have to change some resistors… (I don’t know yet, witch.)

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