Motorised Volume
Handy Howie
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I have an old amplifier that I regularly use in the bedroom.  It is connected to my DVD player,  video cassette player, digital radio and PS2.  I have had this amplifier for many years and have grown attached to it’s retro looks.  It also sounds good in my opinion.  The only problem with it, is that it does not have a remote control.  To alter the volume, you have to get out of bed and actually turn the control.  I could have replaced it with a more modern device like a normal person would have, instead I decided to modify it and give it a new life.

I started by removing the old potentiometer that was used for the volume control and replaced it with a motorised one that I bought off Ebay.  A little ingenuity was needed to get it to fit, but the results were good.

At first I was going to add the control electronics for the motorised potentiometer into the amplifier, but I decided in the end to mount it externally in a small case.  I put a socket on the back of the amplifier to eventually connect to the electronics.  This way, I didn’t need to open the amplifier anymore.

The Sony remote control for my video cassette player has volume control buttons on it for controlling a Sony TV.  Since I don’t have a Sony TV, I decided to use this remote control for adjusting the volume on my amplifier.  I used my oscilloscope to look at the signal from the remote control when pressing the volume up and down buttons.  I then designed the circuit below which is based around a Microchip PIC16F84 and wrote the software to read the signal detected by the infra red sensor and control the potentiometer motor.

This video shows the volume control being operated by the remote control.  I have stuck a little piece of black tape on the volume control knob to make the movement more obvious.  It is still possible to turn the knob manually to once again get the full retro feel.