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How to wire the Firefox throat microphone

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Microphone Cable Pin Out

The pin out on the throat microphone is not standard. The voice line is the middle section of the barrel while the ground is the back section (standard). The tip is for the ear piece. Photo 1 shows the pin out. This pin out will not work with any standard amplifier such as the Radio Shack amp. Most amplifiers expect the voice to be on the tip of the plug. You will need to either build an adapter cable or cut the end off of the throat microphone cable and put a new end on with the proper pin out. I believe most amps are also expecting a 3/8� (3mm) where as the throat microphone has a 2.5mm plug. See my warning below about cutting the original cables.




How to Power the Microphone

The throat microphone is a powered microphone. You will need to run 1.5 volts through the voice line. You can run higher volt levels but you may need to increase the resistor you are using. I found that if you run the voltage from the amp you can get loop back ground noise. I do not know how to eliminate it. I recommend running power from a separate battery, such as AA battery (1.5 volts). You will most likely need a capacitor on the voice line to the amp input. Figure 2 shows how to wire the microphone with power. Those of you with more knowledge of electronics might recommend different values for the resistor and capacitors.




Warning Regarding Cutting the cables:

If you plan on cutting the original cable and modifying it you need to know that the cable has 2 sets of wires in it. One set is for the ear piece and that can be ignored. The second set is for the microphone. These wires are very fine and can be difficult to work with. If you have experience working with a soldering iron you should be OK. To make matters even worse, the wire inside the PPT cable is even finer AND it is coated with a resin for insulation. You must remove the resin before you can solder those wires. I found attempting to melt some solder onto the wire and then remove the solder using solder wick will clean the wire up nicely.


Image of original microphone cable after cutting off the plug. (I do not have any photos of the PPT cables cut)



My Cable Assembly:

So here is the cable I built. I did cut off ends of the original cable. As I said before I found the 2.5mm plugs and jacks to be such poor quality that they would not maintain a connection. So I went with RCA (yes that's RCA). I use RCA between my amp and the mic.




I replaced the PTT buttong because I thought it was big. I'm a small guy so bigger guys or at least guys with roomier gloves may have no complaints. I used a surface mount momentary on switch which I bought at Radio Shack. They have two types. I got the larger one because the button sticks further out. I found with the smaller which I tried first that it was too hard to work with gloves on. So from the helmet down to below the neck line of my armor I use the coiled cable. That keeps me from having to have someone stuff the cable back under my armor every time I take my helmet off. I then run a flat cable down my arm to my hand. I can run the cable under my underarmor so you cannot see it.


New PTT Button:




Full Cable Assembly




You won't see the power for the mic in my cable. That is wired up to my amp inside my helmet.


Here is the updated video link


Here's the link to the demo of my old radio shack clip mic. It sounds OK in the demo but people always had trouble hearing me.

Edited by gmrhodes13
link removed no longer working
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Just asking.....

1.- why have a PTT, why not leave it open mic.

2. How or better said what do u do to remove your helmet with out messing up your voice system...... wait were is your system??? is it self contanied in your helmet?


thanks for sharing!

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You can't leave the mic open because it rests on your neck and every time you move your head you'll hear it scratching against your neck. If you look at my thread on the "tiny amp" you can see my sound system. Its mounted in my helmet. I use the coiled cable between the helmet and PTT button to make it easier for taking the helmet on and off with out having some one restuffing the wire under my chest armor.

Edited by kiyotei
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