Hertz HRC Sub Volume Remote Control Circuit

I tried to find any kind of information of the Hertz remote volume control circuit, but no luck. Finally I decided to buy it and open the box for investigation.

 

The result is sad... It is the first time in my life when I bought so highly overpriced potentiometer and it is connected in rheostat mode.

Pictures of the unit are here:

 

The circuit is simple:

 

If the impedance is 50k ohm or more, the amplifier gain is maximum - ie. volume control module is not installed. The gain is minimum if the impedance is zero ohm. The potentiometer is linear and has center position (you feel the click) and the impedance in this case should be 25k ohm, measurements on original unit shows result as 23.7k ohm. The price of this potentiometer is quite low. In ebay it is available as 5pcs and 2USD (shipping included).

So, think twice. Do you need to buy plastic box which is littlebit bigger than matchbox and includes only one potentiometer?

Maybe you need only potentiometer (one/two USD) and you can install it somewhere next to your other switches (seat warming buttons etc.).

 

 

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