PC Audio Generator

Building a AM/FM Radio kit and you test each section after construction, so far I have not screwed up, now I am at the part where I need to use a 'audio generator' and introduce a signal into the board. As I don't have this piece of equipment found one on the net which will allow me to create the tone at the frequency required (400HZ), I can attach a cable to the 'output' or 'headphone' jack of the PC and can hear the tone there, first checked with headphones.

How to I get the tone to the circuit, I have a 6' stereo cord with stereo connector at each end, cut of one end and found (2) wires within it, though I would solder a clip to each one of the and attempt to use it to 'inject'? This is where I am lost, how do I get the 'tone' from the PC to the circuit?

Thanks!

PinkFloyd43 - The Dark Side Of The Moon

When you cut the stereo connector off, you should have found either 2 conductors plus a shield around the pair, or else 2 conductors each with its own shield. You want to use one of the conductors as the signal source, and connect the shield to the common ground of the circuit you are injecting it into.

If you are using Daqarta as the signal generator, there are separate Left and Right volume controls, so depending on the conductor you choose you may need to adjust the corresponding control. If you want to determine which conductor is which ahead of time, you can use an ohmmeter to check for continuity. The Left conductor goes to the tip of the plug, and the Right goes to the little ring next to it. The shield(s) go to the rest of the plug. Just check which conductor has "zero" ohms to the tip, and mark that Left and the other Right.

I don't know what instructions your kit has about how to inject the signal, but if there aren't any I'd put 10K-100K in series with the signal for starters. This is more to protect the kit than the sound card, which is typically able to handle a short circuit.

Best regards,

Bob Masta DAQARTA v4.00 Data AcQuisition And Real-Time Analysis

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