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Homemade CB Intercoms Section

By Jesus Davis,2014-06-17 00:48
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Homemade CB Intercoms Section ...

Homemade CB Intercoms Section

     First, I found a small mobile CB with PA in it, and had a CB technician peak it out and had it wired for "Talk Back". The "Talk Back" feature can be installed by most CB Shops, and is the key to making it work right. For those that have never heard of "Talk Back", when you key the mic and talk

     into it, you will hear your own voice coming across the speaker as you are transmitting. By having "Talk Back" installed, each time you transmit, your voice will come through in the speakers inside your helmet. Otherwise you and your passenger would not be able to hear each other. (Also be sure the CB you use has external jacks). Install the CB in the bike and plug in a mono plug cord in the back. (I don't know for sure which jack mine is plugged into because I plugged it in after the CB was installed and can't see the jack to see which one it is, but I think it's in the speaker jack, not the PA jack). The wiring is a bit complex. I wanted to be able to use it as a CB and Intercom, so I bought a small 4 pole double throw switch to switch between CB usage or Intercom usage. This was a little hard to find, but I finally found one at a local electronic supply store. I couldn't find them at Radio Shack. I then cut the microphone cord of the CB, leaving it just long enough to hook to the center contacts of the 4 pole double throw switch. There were 4 active wires in the mike cord, and I hooked them separately to each of the center contacts on the switch. For cords, I went to a music store and bought a 20 foot and a 15 foot section of Midi Cords with male ends on them. At Radio Shack I bought 2 female midi cord ends. Then I measured off enough wire with a little extra for 2 runs. One to the passenger, and one for the driver, and each run has one of the male plug ends on them for looking to the helmets.

    The midi cords have 5 wires in them including the shield wire which I did not use. 2 of the wires I used for the mic and 2 for the speakers for each helmet. I also bought 2 Midi couplers to make the connections from the bike to the helmets, at Radio Shack. I found this was easier than soldering on female ends to the cords. (The helmet wires came from the other Midi Cord, and had male ends on them also.) Select 2 of the wires on the radio end of the cords and hook them to the external speaker cord.

     (NOTE: After running all the wires and hooking the helmet wires to them be sure to check with an ohm meter from each colored wire from one end to the other. I found that the second midi cord I bought for the helmets was not wired the same as the first.)

    I ran another run of Midi Cord from the CB to the left handgrip for a PTT button. I found some little remote control sized project boxes at Radio Shack and bought a couple of momentary push switches that fit really nice in them at the electronics store. I just used simple 2 wire switches. Now you need to open the back of your original CB microphone and look at how the wiring is. Mine had a double pole double throw switch in it, and I found that one of the wires was breaking contact when I pushed the mic button. For the intercom side of the system on the 4PDT switch I left this wire open in wiring it up to it. When you push the button on the original mic to talk, it was making contact with 2 sets of wires. One of them makes the circuit for the microphone, and the other makes the circuit for the transmit inside the radio.

    For the intercom side, I used a jumper on the side of the 4PDT switch for the transmit side, which keeps the transmit contacts closed at all times. This way I was able to use only a 2 wire PTT switch, because a 2PDT

     Momentary switch that would work in the little remote control project box proved impossible to find. (I found that running both mics in the helmets at the same time, caused the mics to not pick up well enough, so that's why I used PTT buttons to break contact for the microphones in the helmets.)

    For the rear passenger I used a couple more of the little remote control project boxes which hooks up to the plugs between the passenger helmet and the bike. One of these boxes is where the PTT button for the

     passenger is, and it has about a foot long piece of Midi Cord going from it into the other little box which is a junction box, between the passenger's helmet cord and the cord on the bike. (It would be simpler to have added it into the rear helmet cord or to the bike cord, but I did it this way so that the helmets could be switched around if needed.)

    Note that this worked really good for me, with my setup. We have a 1982 GL1100 Interstate, and I mounted the CB and the 4PDT Switch in the left side of the fairing inside the cover plate. Some of the ways I did mine may or may not work in your case, and you will have to use a little ingenuity to make it

    work, but the end results in my case, were as near a factory look as can be. Not only did this setup really work, it looked nice, and the headsets turned out to have a "factory look." (I'm a perfectionist of sorts, and did not want to cheapen the looks of the helmets or the bike.)

    I haven't totally figured the cost, but after spending $25 for a good used CB, and everything I bought to put this together, I would guess that I have between $125 and $150 tied up in this setup.

    One more note.......If you don't think you can do this, DON'T! This took a lot of time, and a lot more trouble than I ever imagined......finding the right parts that would work out right, putting it all together, plus having a little of basic knowledge of electricity helped a lot. This information is only intended as an example of how mine worked, and you will probably have to modify these instructions to work with your bike and/or CB Radio. But I did get a lot of enjoyment out of building these, and am proud to show them off, because I did it myself!

     At the CB shop, I bought a couple of cheap $5 microphones that had small mics in them. These mics are about the size of a pencil eraser, and Igutted them out to get the mics. If you have a full face helmet, mounting the mics should be fairly simple. You can just cut a piece of the foam out big enough for the mics and run the wires.

     In my case though, I have open face helmets. Here's what I did: I found a local Auto Parts store that sells some pretty fancy oil cans which had the perfect size spout. It was a metal flexible spout. These oil cans sold for about $18, but the guy at the store, (a biker himself) said he could get the spouts for them alone, which costed about $6 apiece. I bought the spouts, as well as some heat shrink tubing to fit over them. I measured and cut both ends of the spouts off, and the inside was just barely big enough to fit some aquarium tubing through the inside of them to protect the wiring, and then I ran 2 single strands of wires through the tubing and hooked to the mic. (I left the aquarium tubing long enough to go all the way flush with the back end of the mic.) To mount the mic to the oil spout tube, I found all sorts of plastic tubing to choose from at Home Depot. I used some whiteish colored, stiff tubing to mount the mic inside

     of, and some soft clear plastic tubing to hook it to the oil spout tube. I put a very small clamp over the tubing just behind the mic which serves 2 purposes....One, it helps hold the mic on, and 2, it gives something to hold a foam mic cover on.

    Next, I slid the black heat shrink over the oil spout tube, and heated to shrink. Perfect! At a local bike shop, I bought a couple of the big foam mic covers to put over the mics. My helmets have removable earpieces which are velcroed in, so I pulled them away and slid the back end of the boom in behind them and ran it all the way to the innards of the helmet, past the chin strap bracket. Then I used a large plastic pull tie to strap the boom and the headset wire to the chin strap bracket, and pulled it really tight, then cut off the excess.

     Worked good on mine anyway! I ran 2 speakers for each helmet. For the CB side of the system, for now, I just hooked the rest of the CB microphone to the top row of pins on the 4PDT switch mounted near the CB, and as soon as I find a double pole double throw momentary switch which I can mount into something small for another PTT button, I will beable to wire it up to also be able to use the headsets for communications on the CB!

     See a Wiring Diagram I made to build these.

Homemade CB Intercoms Section

    Note that this worked really good for me, with my setup. We have a 1982 GL1100 Interstate, and I mounted the CB and the 4PDT Switch in the left side of the fairing inside the cover plate. Some of the ways I did mine may or may not work in your case, and you will have to use a little ingenuity to make it work, but the end results in my case, were as near a factory look as can be. Not only did this setup really work, it looked nice, and the headsets turned out to have a "factory look." (I'm a perfectionist of sorts, and did not want to cheapen the looks of the helmets or the bike.)

     I haven't totally figured the cost, but after spending $25 for a good used CB, and everything I bought to put this together, I would guess that I have between $125 and $150 tied up in this setup. One more note.......If you don't think you can do this, DON'T! This took a lot of time, and a lot more trouble than I ever imagined......finding the right parts that would work out right, putting it all together, plus having a

     little of basic knowledge of electricity helped a lot. This information is only intended as an example of how mine worked, and you will probably have to modify these instructions to work with your bike and/or CB Radio.

    Below is a wiring diagram that I made up to go by in setting up the microphones in this intercom system, using a mobile CB Radio. The speakers are not shown in this diagram, but are fairly simple to hook up. Simply hook a mono plug cord in the speaker jack on the back of theCB, and hook the two wires from it to the driver and passenger cords on the bike, and hook the speakers in the helmets to the matching pins in the plug-ins to the bike.

    NOTE: This wiring diagram works with the microphone that goes with my CB, and will most likely be different than yours. You will have to dissassemble the original microphone for your CB and figure out which wire is doing what. Your mic will probably have a double pole double throw switch in it, and if like mine, when pushed, it will break contact with one wire on one pole, while making contact to the mic. On the other pole, mine only made contact with another set of 2 wires which puts the radio in transmit mode.

     I could not find a momentary double pole double throw switch that I could mount in a project box, so in the diagram, on the 4 pole double throw switch I used jumpers on the intercom side of the circuit to keep the radio in transmit mode at all times while in "Intercom Mode". However when the 4 pole double throw switch is switched into CB mode, you will definetely need a remote momentary double pole double throw switch in order for it to work right. Note also that in "Intercom Mode" I am setting the CB in "PA Mode", so it doesn't matter for the transmit wires to be closed at all times.

    Since a momentary double pole double throw switch which can be mounted in a project box seems to be impossible to find, I have been thinking about the possibilities of using a plain 2 wire switch with a couple of relays to do the switch. If I find that this can be done to finish the CB Mode side of the system, I may change the wiring for the Intercom Mode as well. Just something to think about.

    Here's the diagram:

    I mounted the 4PDT Toggle Switch shown in the diagram above in the cover plate on the left side of the fairing. This is also where the CB is mounted. When the switch is flipped one way, it is making contact fromthe center contacts to the upper contacts. When flipped the other way, it is making contact from the center contacts to the bottom contacts.

    Below is a Wiring Diagram of the Original Microphone that came with the CB, and I included it in order to give a better understanding of how the wiring was originally.

     Again, as noted before, this is just how mine was wired, and yours will most likely be wired a little differently. You will have to look at your own mic, and figure out how it is wired and how it switches.

http://www.cybertution.com/cyberbugs/goldwing/

    http://www.cybertution.com/cyberbugs/goldwing/intercompre.html

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