Advanced Electronics puzzle

[jdrexx]

I bought a dual audio cdrom cable which can be used to feed the audio from 2 cdroms into 1 input on your sound card without interference. I am trying to reverse engineer the thing and am having a tough time.

This is what the original piece looks like:

http://people.ne.mediaone.net/jdrexx/DUALAUDIO.JPG

and this is how I think it is wired:

http://people.ne.mediaone.net/jdrexx/SCHEME.JPG

I think the surface mount pieces on the board are capacitors but I'm not sure. If I measure across either of the "104" pieces, they measure .004 microfarads and if I measure across any of the "472" pieces, they read .083 microfarads.

With the assumption that these are capacitors, I tried to build a replica of the original using capacitors with the same "values" typed on them but my replica piece doesn't have anywhere near the same readings. I built the replica based on the schematic I drew.

I want to build a replica of the original piece and I want to build one that can be used with 3 cdroms (instead of just 2)into 1 audio port.

Does anyone know if these are capacitors or something else? What am I doing wrong? How should I build the duplicate piece and how do I build one meant for 3 cdroms?

 

[AbeStein]

Someone over at

http://www.audioasylum.com

might be able to help.

Abe

 

[stevieblunder]

These are resistors. 472 is 4700, ie 4.7K Ohms and 104 is 100K (100,000). Read two digits and the number of zeros. The 100K resistors are optional. I would have put 4 of them at the inputs to avoid the additional loading rather than on the outputs. The point is that two voltages can not be connected directly together. This is a resistive mixer that will give you -6dB loss as long as both sources are connected, more loss if the input impedance (load) is not very high, ie less than 10X, ie <~24K.