Is this possible

[thetikiman]

I want to make a device that controls a video signals by sound. So basically when the room is quit the signal on the tv is static and the louder the room is the clearer the tv signal. The device is going to be used for a bands live show.
Does anybody have any ideas?

 

[Nigel Goodwin]

I want to make a device that controls a video signals by sound. So basically when the room is quit the signal on the tv is static and the louder the room is the clearer the tv signal. The device is going to be used for a bands live show.
Does anybody have any ideas?

You first need to generate a DC voltage which represents the volume of sound, you can do this with a precision rectifier - look for VU meters or AC milli-voltmeters.

You can then use that voltage to control the AGC line in the TV, altering the gain as the volume changes. Many modern TV's mute the picture with no signal, so you will probably have to disable the mute circuit. In any case, you are going to need the service manual for the TV and a good working knowledge of televisions.

You could also built an external voltage controlled attenuator, but you would probably still need to modify the mute circuit in the TV.