Audio Override

Hey All, This is Utadventure's son again.

Lately I have been working on a project and now that it's done I thought you all would like to see it.

I have a bike that did not have a cb installed so I bought an aftermarket one off the internet. After a while I realized that while it was nice to have a cb I would also like to be able to listen to my iPod while on the road. At first I just spliced a headphone cable into a 5pin din plug so I could do this. This didn't last long cause while I could listen to my ipod or my cb I couldn't listen to both cause they interferred with each other and i didn't want to ruin one with the sound coming from the other.

What I wanted was a box that I could plug both my ipod and cb into that would swap between the two depending on wich was putting out sound. I checked at WingDing and searched the internet but couldn't find one that was sold seperately.

I got together with a neighbor of mine and showed him what it was I was looking to do and together we came up with some plans. The box I built cost me about $35 and a few hours of soldering the components together.

The box has 2 inputs and 1 output. Now the inputs could've been anything i wanted but i have a 3.5mm jack and a 5pin din. the 3.5mm jack is normally closed so even if the box is off it will still go through to the output. The 5pin din input is the cb, any time sound comes from the cb it cuts the primary input (ipod).

The sensitivity to trip the switch can be changed so that it isn't tripped until the cb is loud enough.

I'll be posting pictures with this post. The top has an on/off button, a power indicator light, and a swich indicator light to tell when the secondary input is overriding the primary.

I've tested it in the garage, bike running and all, now I just need to take it out on the road.

Inquiring minds want to see the schematics......

I've been wanting to do the same thing, using a gps with mp3 capability instead of an IPOd. I'd like to hear music, interrupted by gps directions, or by CB. I'd sure like to see a schematic of what you did. Sounds pretty cool.

Here is a schematic of what I did. The R8 resistor goes to the positive of the switch.

The switch I used flipped 2 circuits at the same time and had a normal open connection and a normal clossed connection. So the iPod went on the normal closed and the radio on the normal open. and the 2 circuits were just the right channel on one and the left channel on the other.

The indicator LED I wired in parrallel to R8 so when the switch was thrown so was the LED. (If you understand all the techno babble then you should beable to figure out the on off switch and the power indicator light on your own) lol:happy65:

Along with the schematic I have uploaded some more pics cause the first batch was blurry.

Edit: Pls understand that while it has been successfull on my bike this circuit is still largely untested and un proven so if you deside to use this pls don't blame/sue/bad mouth me etc. if your bike blows up cause of it.

Finally with the last few days of good weather i've been able to road test this. Works great with no problems!

Downsize it a bit, put it in one of the Radio shack plastic project boxes and sell, sell, sell! I have done a similar thing but it was no where as neat or sophisticated!

Downsize it a bit, put it in one of the Radio shack plastic project boxes and sell, sell, sell! I have done a similar thing but it was no where as neat or sophisticated!

Will do when I make one for my mom. Probably make it so that it fits in a tank bag or such.

I have looked the schematic over several times, I do not see the out put or the second input.

That IC and components should fit into a 3" x 5" x 1" box shouldn't it?

I've included a few more pics for clarification

The sound in on the schematic is solely for detection purposes it doesn't actually come back out any where. R8 leads to the relay switch itself to power the flipping of the switch.

the relay schematic looks something like the 2nd pic.

By doing things this way there is no sound degredation from passing through all the little components and it makes it easy to swap the places of the inputs by simply swaping them on the relay.

And yes they all should fit just fine into a 3x5x1 box thats what the one on my moms is like.

Ah, so you are using the 555 as a key for the relay. I was wondering how you could switch ac(audio) with a dc device. I have been tinkering with this for several months trying to accomplish this with no external relay. There actually is an IC on the market that will switch this and handle about 10 watts of power. Problems are twofold though, it is SM, about the size of a pencil eraser and only available one place in the world with a 10k mini order. If I knew what to do with the other 9,998 of them I would order!

the relay i'm using is smaller than the 556 that i'm using (instead of buying 2 555 i figured it'd be easier) so it still is part of the box just not included in the schematic for simplicity.

on the board i'm soldering it all to it only covers a 6x4 pin area.

When you'd like to have one tested with a Garmin Zumo 660, let me know - I'll even pay for the device!

My solution was to use the electronics in the bikes intercom that already does this.

Gps is inserted into the rear passenger mic audio. It interrupts everything all the time.

Ipod is going into the Cassette input, I gutted the cassette and turned it into a mp3 player holder. works great my scosche RF remote for the ipod still works through the metal can the cassette player was in.

My ham radio is going into the CB radio input 6 pin din plug. I made a similar circuit to bring the radio mute pin high when squelch breaks on the radio to mute radio and intercom when audio comes in from that source.

My only switch is the "enable mp3" button that does the same thing as the cassette does when you push the tape in.

This works very well. only drawback is that you do not hear the GPS instructions from the dash speakers, but that is not an issue for me.

Tim,

The circuit you describe sounds far more simple than where I am. How/where do you signal the mute pin with the 6 volt signal? Is your audio from ham unit clunking a relay in addition to feeding signal or did you go on the board and tap the AGC circuit?

Where would I pick up the rear mic cable in the fairing? Does this also allow you to feed audio back to the radio to tx? I'm using an Ht that when keying sends audio through the outer ring via taking center to ground. Typical of Kenwood and Alinco.

More info please!

Tim, you are now my second best hero. One question. Did you do anything to attenuate the power of the gps? Seems it would be a lot more than the mic power, even at the low setting.

Quick notes, I dont have the pinouts here in front of me at work.

GPs -> 100K ohm pot + 10uf cap to eliminate any DC. adjust until audio level is the loudest you want at max volume setting on the gps. now you can adjust volume at gps. simply tap into the MIC+ at the rear headset connection.

I found and verified pin-outs for the CB connector, there is a pin that when you give it 6V it mutes the stock audio so the CB takes priority. I made a circuit very silimar to above that when the audio level get's high enough, it creates a 5V signal (good enough to trip it) on that pin.

audio out to CB -> mic in on the dual band radio with some attenuation.

audio out from dual band radio -> to CB audio in on connector.

as for the ipod connection, I just followed the instructions I found here, but chopped off connectors as I will never want a Cassette again.

I'll be doing a full write up in my radio pinout thread as I get the information together.

There is a lot of functionality in the stock radio system. and most of it can be duplicated in the 2nd gen if someone had the time to find the same pins as I have on the 2nd gen system. I am sure that most of it will work on any bike intercom system as long as it has the inputs, Injecting audio into the Mic for the passenger would work on any system, you just have to get the level right (I'd add a 10uf cap before the pot to eliminate any DC voltage as well)

Also use a metal enclosure for any circuits or to hold the pots and shielded wire for any runs. a bike is full of electrical noise and the Mic input is really sensitive.

I am sooo jealous of you folks for understanding this stuff.

Like a fool, I dropped out of electronics class in High School, then again from Electronic Engineering in College. - I just never could grasp the technology.

I love to read the mags, but only grasp bits & pieces.

Some of you electronics folks talk the language like it is your first language. As I said above, I'm jealous.

craigr