Audio A/B switch with self-power

[danickstr]

Hello all. I am an electrical contractor and was wondering if anyone knew of a means by which it would be possible to have an auto-sensing A/B switch that could use the signal line voltage to make the switch relay open the B path if it sensed a signal? Ultimately then I would like it to be on a dongle with a Y-cord type of shape, the dongle being in the middle and not too fat. My purpose for this would be to send audio out of the DVD to the in-house speakers when someone watches a DVD and otherwise to have it send audio from the satellite box.

My reason for not using other boxes on the market is that they are bulky and require a "wall wart" and it seems that the switch transistor would need so little power to open the B path and close A.

 

[zevon8]

Not sure if this helps or not, but many higher end surround sound receivers will do this for you already. They will sense which input is active and select this as the source signal to amplify. Generally what they do is select the highest quality signal available for a given type of device and use that input. You can use this feature to "trick" the receiver into auto selelcting a source for you.

For example : the DVD is connected to use the descrete 6 channel input & component video output, and the satellite box is connected to the 2 channel input & the TV's video input. The 6 channel input is considered the better signal over the 2 channel, so when the DVD player is on, the receiver will choose that audio input and also select the corresponding video connection. When the sattelite box is on the 2 channel audio input will be selected with its video connections. The receiver is left set to video input.

I have done this before when there were not enough separate inputs for all of the video sources, but there were different "types" of inputs/outputs for the same video sources. You can still manually select input / output combinations via the receivers controls, but the auto select feature will handle everyday combinations.

 

[danickstr]

thanks for pointing that out. i guess when i consider the cost of doing this it would behoove me to just buy a better receiver for them. i am trying to send these signals from two different rooms though as well so i was going to put this thing near the input to the whole house reciever which is in another location altoghether from the two sources. i can do it with a wall wart i guess just hate those things. or i could tap into the dc in one of the amp units i guess as well.