Stereo to mono converter

Inside view of my stereo to mono converter.

My TV camera generates stereo audio, like most cameras do. However, my local ATV repeater only supports mono audio. So to transmit a nice audio signal with my TV pictures, I needed a way to convert the stereo signal to mono.


Searching the web for a simple solution I found this circuit, published by Peter N. Petersen:

Circuit of a simple stereo-to-mono-converter

The circuit is a traditional opamp based mixer. The opamp suggested here is a TL072, unfortunately that chip was out of stock here. I found a nice replacement in my junk box: the LF356, although it has a different pin layout. Most opamp’s with FET inputs will probably do the job.

Part list:

R1   47k
R2   47k
R3   27k
R4   10k
R5   10k
C1   1uF / 16V
C2   1uF / 16V
C3   3.3uF / 16V
C4   10uF / 50V
U1   TL072, OP27, LF356, etc... (check the pin layout of the selected opamp)

Check out Peter‘s website for more details.


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