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Automatic Audio Input Selector

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smit6089

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I am not totally green to electrical circuits but I am still a complete rookie. I have something in mind that I am wanting to build but I have no idea where to start. So I came here in hopes of finding some guidance.

What I'm wanting to build is an automatic audio input selector. I want to have INPUT A to play though OUTPUT unless INPUT B has a signal. When INPUT B has a signal I want it to be the output.


Example... I would have a CB radio and my PC output hooked into this device and this device would in turn be hooked into my speakers. All though standard 1/8 audio jacks. The PC audio will play through the speakers unless someones voice comes over the CB in which the CB would play over the speakers instead of the PC...


I hope this makes sense. If it doesn't please ask questions. Any help would be greatly appreciated, a diagram would be a godsend. Thank you all for your time.
 
I thank you very much for your reply. And indeed a VOX circuit is a good start to what I am looking for. But how would I use this circuit to stop an input and play another input. To be quite honest I work for a retail chain and my job title requires I wear a two way radio but I am hoping to find a way to listen two an mp3 player through my two way radio headset while maintaining it's functionality. maybe I am too much of a rookie to see how to use the VoX circuit but any more help would be much appreciated.
 
Are you up to building a circuit with an opamp, diodes, resistors, capacitors?

Have you thought about just using a simple resistive combiner that simply sums the two audio signals to one set of headphones.?

Does the two-radio have an LED which lights while it is receiving a signal?
 
Two way on left and MP3 on the right side of haed phones? This is a simple mater of a spliter. Andy
 
This is a very quick visual of what I'm wanting to do.

**broken link removed**

I just want music to play though the headset unless the radio receives a signal. I want to do this without altering the radio in any way. I am capable of building basic circuits I just really am not sure where to get started.
 
Any more ideas or suggestions? And thank you to all you have posted. . . I'm just hoping I can get this thing figured out.
 
Well, this may work for you. I just threw it together (Have not built it). Seems to work with simulations.

Here is the sim output and schematic.

voxsim.gif

The parts can be obtained from digikey.

Digi-Key Just type PN in search window, ie. dg441

Important data sheets.
https://www.electro-tech-online.com/custompdfs/2010/11/fn3281.pdf
https://www.electro-tech-online.com/custompdfs/2010/11/LM193.pdf

The pot is to adjust threshold for radio detection.
 

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This circuit is a mono switcher. For stereo sources, I would simply run two of these, or is there a better solution? JL Audio has a version of what I want. It is the CL-SES. However, I want a portable self contained unit using 3.5mm input and output jacks. I would like a minimal footprint. I have an associates in electronics engineering technology, but that has been awhile and it has only been the basics that I have used as a service technician. I want to hook up an iPhone and a Sat Radio for inputs and the output runs to the front panel aux-in jack of the head unit. I would prefer a more integrated approach with everything hard wired, but money and one being a company car prevents that. If I get the CL-SES, I can do what I want. I will have to get the 3.5mm to RCA adapters and wire up a lighter power adapter. The CL-SES can be had for less than $100. Should I build exactly what I want, or should I just get the commercial product?
 
I know this thread has been dead for a while, but I'm hoping someone can help me out. I'm looking for something that can do exactly what smit6089 brought up. Switch from audio A to audio B when something comes across on B.

I'm just some schmuck who knows diddly about how I would make this work. Not an engineer and have a pretty (re: VERY) basic knowledge of electronics.

If you guys could point me in the right direction that would be awesome. Or hell, if someone would be willing to build me a unit that could do this, I'd be willing to pay for services. Shoot me a PM if interested in the latter to work out details.

Thanks guys.
 
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