This is a two part project. I cant hear my CB or Ham radio (yes I have loud ext speakers) very well when the air conditioning is on or the windows are down on the interstate. I researched fixes and nothing seemed very good or very cheap. I think I have found something that will work good for me and thats to pipe them into the car stereo. I'm going to have to figure out two different things to make this work.

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1. I need to add a AUX input to my stock radio or buy a cheap head unit. There are a few solutions that add a AUX jack but they are more money then a new head unit.

-This radio used to have a 3 CD disk changer(model L4200) so there is a audio input pathway for that on the head unit. The CD path does not sound like it will work without figuring out how to fool the radio into thinking there is still a CD changer plugged in. I would have better luck connecting a Ipod I think.

-It also has a tape player(model 51706) and that also has a audio input pathway. The tape player sounds like a easy target and has been used before on other Toyota radios. The audio lines from the tape deck are disconnected but the tape motor drive is still working so that allows it to think everything is normal.
http://www.youtube.com/watch?v=bRIswrodoM8



2. I learned on expo that I need to make a passive mixer that can deal with speaker level outputs(Ham, CD) and line level outputs(tablet, phone). As long as I am piping coms into the stereo then the phone and tablet should be piped in too. That way I can get rid of the two ext speakers and the bluetooth-FM transmitter. The mixer will take all of these input sources and combine them into the one AUX input.

-A passive mixer will isolate the outputs from one another so that they are protected from each other and damage. It does this with just resisters but will attenuate the signal some depending on resister value. Knowing nothing about the signals I guessed some resister values based on others projects.

-Normal speakers are not ideal for Ham or CB. Dedicated coms speakers lack performance on freqs outside the human voice range. I expect to have a bit more static coming through then I have now and hope the overall set up dosnt induce too much noise.

-I'm going to try and use variable resisters to bring the Ham and CB to a slightly higher volume at a given car radio volume.