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A Low Power Wireless Audio Power Amplifier

Konusu 'Fm Verici Devreleri' forumundadır ve guclusat tarafından 12 Ekim 2015 başlatılmıştır.

  1. guclusat

    guclusat Tanınmış Üye Süper Moderatör

    14 Haziran 2009
    Ödül Puanları:
    Battery-Powered portable unit, Suitable for all type Televisions

    Using this low-cost project one can reproduce audio from TV without disturbing others. It does not use any wire connection between TV and Loud Speaker. In place of a pair of wires, it uses invisible infra-red light to transmit audio signals from TV to Loud speakers, Without using any lens a range of up to 6 meters is possible. Range can be extended by using lenses and reflectors with IR sensors comprising transmitters and receivers.

    Transmitter’s operation:

    IR transmitter uses two-stage transistor amplifier to drive two series-connected IR LEDs. An audio output transformer (T1) is used (in reverse) to couple audio output from TV to the IR transmitter. Transistors Q1 and Q2 amplify the audio signals received from TV through the audio transformer. Low impedance output windings (lower gauge or thicker wires) are used for connection to TV side while high-impedance windings are connected to IR transmitter. This IR transmitter can be powered from a 9V mains adapter or a 9V battery. Red LED (D1) in transmitter circuit functions as a Zener diode (0.65V) as well as supply-on indicator.

    Transmitter diagram:


    Wireless Audio Power Amplifier Transmitter Circuit Diagram
    Receiver’s operation:

    IR receiver uses popular op-amp IC µA741 and audio-frequency amplifier IC LM386 along with phototransistor L14F1 (Q3) and some discrete components. The sound generated by TV set is transmitted through IR LEDs, received by phototransistor Q3 and fed to pin 2 of IC µA741 (IC1). Its gain can be varied using potmeter P2. The output of IC µA741 is fed to IC LM386 (IC2) via capacitor (C7) and potmeter P3. The sound produced is heard through the receiver’s loudspeaker. Potmeter P3 is used to control the volume of loudspeaker SPKR (8-ohm, 1W).

    Receiver diagram:


    Wireless Audio Power Amplifier Transmitter Circuit Diagram

    P1 = 10K
    P3 = 10K
    P2 = 1M

    R1 = 4.7K
    R2 = 22K
    R3 = 100R
    R4 = 10R-1W
    R5 = 10K
    R6 = 10K
    R7 = 15K
    R8 = 15K
    R9 = 100K
    R10 = 680R-1W
    R11 = 1K
    R12 = 10R-1W

    C1 = 220uF-25V
    C2 = 220uF-25V
    C3 = 10uF-25V
    C4 = 220uF-25V
    C5 = 220uF-25V
    C6 = 100nF-63V
    C7 = 100nF-63V
    C8 = 100nF-63V
    C9 = 100nF-63V

    D1 = Red LED
    D2 = IR LEDs
    D3 = IR LEDs

    Q1 = BC547
    Q2 = BD140
    Q3 = L14F1

    IC1 = uA741 Opamp
    IC2 = LM386

    J1 = Audio input Jack
    T1 = Audio Transformer
    SPKR = 1W-8ohm

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