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I need a hardware volume leveller/normalizer for analog audio from cable box to tv. (schematic or product)?

Searching around I've found several shareware software programs - installing an extra computer for this task isn't an option. Ibles doesnt seem to have anything like this... I'm thinking an arduino, a sneaky sketch, and an lm-series stereo volume regulator. All the hardware I've seen dies a quick death - presumably the way of the electric car - too much lobbying from advertising industry to stop them hitting store shelves. Frankly, I think its beyond un-ethical. In my particular situation, its potentially dangerous.

NachoMahma8 years ago
. Try looking for Automatic Gain Control (AGC) circuits.
frollard (author)  NachoMahma8 years ago
Thanks - will use *that* search term...wish me luck!
legionlabs8 years ago
It would be ugly, but you could do it with opamps and an MCU such as an arduino. You could use the ADCs on the Arduino to monitor the audio signal strength, then use PWM outputs to control a voltage controlled resistor (lousy version: an LED coupled to a photoresistor). This voltage controlled resistance would be the gain-setting resistor on a simple inverting amplifier, built from an OPA132, for instance. I warned you it would be ugly, and I'm sure there's a much better way... but it might let you normalize volumes across a small number of input channels.
frollard (author)  legionlabs8 years ago
Thats pretty sneaky using the passives like that. I will come up with something! Thanks for the reply!