Re: Computer control of an audio multiplexor

Joe User wrote:
I am trying to multiplex a number of radios into the 'Line In' on my computer sound card.

I assume you really want to select one of the radio outputs to go to the sound card. Multiplexing is a different technology en.wikipedia.org/wiki/Multiplexing


I want to send commands from the PC, through the RS232 serial port, or the USB.

I want the radio signals to be switched according to the commands from my PC.

I need the switching to be 6 stereo signals to 1 stereo signal.

Has anyone done this? What is the cheapest, easiest and most flexible way to do this?

It all depends on how you define cheap and easy.

If you are handy with a soldering iron and writing simple programs then using the parallel port to control 6 DPST relays would do what you need. With a well supplied junk box you could do it for under $20.

Here are some links:
www.epanorama.net/circuits/parallel_output.html
ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm
www.dakeng.com/relay.htm
www.electronickits.com/kit/complete/elec/ck1601.htm


Even though I could easily do the above I would opt for the eBay route. What you are looking for is an audio matrix switch with RS232 control. Since you have 6 inputs and only one output then anything larger than a 6x1 switch.

Here are links to VERY NICE AutoPatch half-y units:

cgi.ebay.com/autopatch-half-y-matrix-composite-switcher-with-audio_W0QQitemZ180187334290
cgi.ebay.com/AutoPatch-Half-Y-8x4-Stereo-Audio-Video-Matrix-Switcher_W0QQitemZ320188063634

For my money I would use one of these to do the job. I have done several AutoPatch installations and their equipment is top quality. While you don't need 1/2 of what these units will do the price is right! Notice that the terminals on the first listing are removable screw type while the second listing has RCA terminals which might be handier.

Control software and protocol can be found:
autopatch.com/index.php?object=286
autopatch.com/pdfs/bcs/bcs_serial_control_protocol.pdf

Marc Hult (who posts here regularly) has some Ivie 784PW 8x4 audio matrix mixers in his porch sale for $70. Here is a link:
www.econtrol.org/porch_sale.htm


If you like buying new then these are some audio only switches that could do the job:
www.rdlnet.com/product.php?page=157
www.kramerelectronics.com/indexes/item.asp?desc=324


Other options include using RS232 controlled relay cards like these:
www.6bit.com/products/smartrelayS.php?products_id=34
www.pencomdesign.com/pencomstore/agora.cgi?p_id=0037


I've never used X10 stuff, and would like to avoid it, if I could easily do this with a simple USB device.

Since all the controlled relays are local X-10 is not an appropriate technology. When used properly X-10 can be quite reliable.

Good luck with your project. If you need more information please reply with a bit better description of what types of radios, type of computer and a better description of the total project.
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