TV Muter Circuit

Posted on Feb 5, 2014

Many households are still graced by tube-type television sets. If you want to connect one of these large tellies to your stereo system to improve the sound quality, this is usually not a problem because there are plenty of SCART to Cinch adapters available in accessory shops. However, with some sets your pleasure is spoiled by the fact that the audio outputs of the SCART

TV Muter Circuit
Click here to download the full size of the above Circuit.

connector are not muted during channel switching. This can sometimes lead to nasty signal spikes, which can cause the loudspeakers of your stereo system to emit irritating popping and cracking noises. In such cases it is a good idea to fit your system with a mute circuit. Fortunately, the right time to activate the mute circuit is defined by the fact that the happy zapper presses buttons on the remote control to switch channels, and the remote control emits IR signals. There are even inexpensive ready-made IR receiver modules available, such as the TSOP1136 used here, which produce trains of active-low pulses in response to such signals. About the circuit: when no IR signal is present, a capacitor is charged via P2 and a diode. IC1 is a comparator that compares this IR voltage (applied to its non-inverting input on pin 3) to a voltage applied to its other input on pin 2. This reference voltage, which can be adjusted with P1, determines the switching threshold of the comparator. If IC2 receives an IR signal, T2 conducts, and as a result the voltage on C1 drops rapidly below the threshold level set by P1. This causes T1 to change from its previous on` state to the off` state. As a result, the relay drops out and the audio link to the stereo system is interrupted for the duration of the noise interval. It`s all quite simple, as you can see. If you do not have a stabilized 5-V supply voltage available, you can use the circuit...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Infra-red Level Detector with 555
    Adjustable Auto transformer
    Ethernet board for C64 and SX-64
    Fm Demodulator Circuit
    L4970A Easy 5V 10A Switching Regulator circuit
    oscillator Is this a suitable sine wave osc? how would I control the frequency
    Mains Pulser Circuit
    simple precision current source circuit
    300w Mosfet Linear Amplifier For 50 Mhz
    Circuit power audio amplifier stereo with LM1875 and preamp for NE5532 2 x 20 Watts
    IN8510 and power motor driver circuit composed of DAC7520
    Voice amplifier transistor
    Bidirectional thyristor AC contactor interface circuit