Adapter with amp and mp3 input to headphones

[RussVT]

I am looking for information on how to put together an adapter that has inputs for my amp, and an mp3 player then an output for my headphones. Could I just wire them together or do I need to put something like a diode in between to keep feed back out of the system. Ideally I want to have seperate volume controls for the inputs. I want to be able to play my guitar to music without disturbing my family. Any info woudl be appreciated.

[Nigel Goodwin]

You just need a simple two input stereo mixer, and if it's a passive guitar one of them needs to be a high impedance mono input for the guitar.

[RussVT]

Yeah, that is what I'm trying to get away from. A two input mixer costs money, I have lots of extra cables and parts, I just want to put something together. The input from the guitar will be out of the headphone jack of the amp, so I will not need a high impedance input for the guitar. Thanks for the input though.

[sofaspud]

You could try a passive mixer using resistors and potentiometers, but I'm not sure how well it would work. The first circuit on this page shows the idea. You can add 1k-ohm rheostats for volume control.

[Nigel Goodwin]

Originally Posted by RussVT

Yeah, that is what I'm trying to get away from. A two input mixer costs money, I have lots of extra cables and parts, I just want to put something together.

Not if you build it yourself, I built one to do an 'emergency' disco one night - a double opamp, couple of stereo pots, eight resistors, eight capacitors, and a 9V battery. It wasn't 'pretty', but I designed and built it in about 30 minutes

It worked perfectly - opamp mixers are really easy devices to build.