Categories

Automatic volume tracking for a TV

Posted on Wednesday, October 5th, 2016 in DIY, hacks by DP

pic-exterior_2-600

An automatic volume tracker by KA7OEI:

It occurred to me that I did have a reference on which I could base an outboard volume control: The internal speakers of the TV. I surmised that I could “listen” to the audio level coming out of the speakers and based on that, adjust the volume of an outboard amplifier. I figured that this could work if I could place a sense microphone very close to the speaker and in this way the sound level at the microphone would be very high as compared to the room volume of the external loudspeakers and I could make it so that not only would the TV’s internal speakers still be quite low for a fairly high volume from the outboard speakers, but also prevent sound from the outboard speakers from being picked up by the microphone and cause the volume to increase even more in a feedback loop.

To test this theory I hacked together a bit of code that did nothing but measure the audio level from two sources:  A microphone and the audio line output and then dump those levels, in dB, to the serial port where I could see what was going on .  It seemed to look pretty good as the two audio sources seemed to track fairly well.

This entry was posted on Wednesday, October 5th, 2016 at 1:31 am and is filed under DIY, hacks. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

2 Responses to “Automatic volume tracking for a TV”

  1. Max says:

    Quintessential l’art pour l’art “solution”. Whatever floats your boat i suppose…

  2. sfrtygh says:

    Or you could just implement AGC with a single transistor, just like we’ve been doing for the last 50+ years…

Leave a Reply

Notify me of followup comments via e-mail. You can also subscribe without commenting.

Recent Comments

  • Joe Desbonnet: Ya, I can recommend the low melting point solder. I used brand 'ChipQuik' and it's amazingly easy to use.
  • Jerome: I need a new BusPirate for the Fablab ;) Many thanks!
  • Max: Seems like an unexpectedly violent way to remove the chip indeed. A hot air station should of course do the job just fine, but in...
  • jose: Part removal described here is pure butchery, the cheapest hot air station will do a fast and clean job removing the QFP, heat air to...
  • Cody: Yes please