Extreme Newbie Question

[KingsLaw]

Much like other posts I must qualify this by saying I am brand spanking new to electronics and diy audio. I have been reading everything I could find on the net, however, I am stuck.

I setup a very simple n-channel mosfet amp (from a design of Forrest Mims, did I reveal to much of a newbie status there?) and when I tested it with a 1kHz sine wave it worked... however, here is my problem.

For the input (a portable cd player) I was planning on using a 1/8" three conductor phone jack. Somehow I figured that the first pin (located by the female receptacle) was for the ground and the second and third pins were for left and right stereo (yeah, yeah I just assumed this).

I made a test input and attached wires to each connector. In my bread board, I tested all wires in all possible positions, first connector to the ground, second to the input and third to the input (separately, is the problem?), etc. Anyway unlike the sine wave generator... I would not get any sound at all, so here are my questions:

1. Am I using the right kind of input, or should I be using a rca jack?

2. How do I connect the jack to the amp?

3. Do both wires from the jack need to be connected for the circuit to connect?

Since I am hanging on to my assumption, I am rallying for the third question.

Thanks All!!

k

[GRollins]

1) You can use any type of connector you like, as long as you hook it up consistently.
2) Typically, a jack such as you describe is wired with the tip being the positive of one channel, the ring right behind it as being the positive of the other channel, and the shank--the longest part--being negative/ground for both channels.
3) Yes, you'll need to make two connections for a circuit. In this case, you'd use either the tip or the ring, depending on which channel you want to amplify, and the shank, which will get two wires eventually--one going to each channel's negative/ground. The signal needs a complete path out & back in order to do its job.

Grey

[KingsLaw]

Thanks!!