Hello,
I fear that to explain the full extent of my problem, I would need to post under a false name to spare the embarrassment :-)
To simplify, I have built a couple of boxes to switch between multiple audio/video sources to a single output and they all work fine. What I am trying to do now, is build a box that can switch my PC's audio output to one or more destinations throughout the house. This seems simple enough. The problem comes in with the LED I am trying to add.
I wanted to add a LED for each line so that I can easily tell how many output lines are active. To drive the LED, I need a 3V battery (feel free to correct me wherever I go wrong :-)). I then got a switch where input is connected to the middle terminal, and output can be either of the terminals beside it (3 terminals in total).
To prevent current to the LED from affecting the audio signal, I cleverly decided to place the switch on the ground wire. This however, works fine with the LED, but the sound seems to play just fine *without* the ground wire.
So, I have a couple of questions where I would dearly appreciate any good answer:
- Why is ground not used for audio? Does the recipient device have a common ground or is there a different answer?
- Why does the current from the battery not affect the audio signal at all? This is the one that stumps me. I expected lots of noise, but it sounds just the same. Or am I not listening close enough?
- Where should I put the switch now?
- Lastly, what is a good amount of current to drive a regular 3mm LED?
Eagerly awaiting responses...
Regards,
Cobus Kruger