CB/Intercom mike


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ghostvet
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CB/Intercom mike

Postby ghostvet » Fri Jun 15, 2012 5:46 pm



Howdy all...

I took my cell phone headset with inline mike apart and after some reworking I installed it in my helmet. I mounted the mike in the chin of the modular full face. It works absolutely great when connected to my phone/GPS/mp3 player.

I made an adapter to connect to the bike. The headset speakers work great, but the mike does not seem to work. The CB breaks squelch when I transmit, but I don't seem to be transmitting any sound.

Obviously, the mike is somehow different, or maybe the wiring? The only change I made from the pinout was I had to combine the speaker and microphone grounds into a common ground since it is a 5 pin din, and the headset only has 4 pins (TRRS).

Does anyone know about these mikes? Any ideas? Anyone?

Thanx!

PS- This is also crossposted on goldwingfacts.com



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virgilmobile
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Re: CB/Intercom mike

Postby virgilmobile » Sat Jun 16, 2012 3:41 pm

Your trying to get apples and oranges to look alike.
The original mic designed to work the bike's CB and intercom is a DYNAMIC mic.It's normal resistance/impedance is about 180 ohms and produces a audio level that is much higher than the electric condenser mic you have adapted to your helmet(the apple and orange).
Is there a fix??
yes,but it takes a complete overhaul of what you just did.
You bring the system back to original equipment then adapt the new stuff to it.It is much easier than modifying existing equipment to work with current technology.
Changing the design of the mic level requirements for the CB and intercom systems is tedious and a custom mic pre-amp circuit would need to be calibrated to match each part.

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ghostvet
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1997 GL1500SE

Re: CB/Intercom mike

Postby ghostvet » Sun Jun 17, 2012 12:25 pm

So, then the next question begs, if I were to replace the existing condenser mic with the dynamic mic, what does that do to the phone usage?

Will the dynamic mic work with the headset fit the phone in place of the condensor mic?

What about the DC power coming in the mic line? Will that kill the dynamic mic? Would I need a resistor or a diode to protect the dynamic mic?

I have no problem re-doing everything, but since I don't know what I am doing, sometimes I might ask stupid questions. But, at least I am thinking, right? Lol

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WingAdmin
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Re: CB/Intercom mike

Postby WingAdmin » Sun Jun 17, 2012 12:53 pm

A dynamic mic will not work with something designed to use a condenser, and vice versa. And as you noted, there is DC bias current coming in on the mic line from any device designed for a condenser mic.

It's possible to make a dynamic mic work with a device expecting a condenser. You'll need a (guessing at) 10 uF electrolytic capacitor to block the DC bias (but allow the signal through), and a limiting resistor (no idea on the value) to reduce the large signal coming from the dynamic mic to the signal level expected by a condenser mic preamp.

Working the other way, making a condenser mic work with a system meant for a dynamic mic is tougher, because you have to build a circuit capable of providing a bias current (and blocking that current from getting to the device) as well as a microphone preamp to amplify the signal to dynamic mic levels.

Using a condenser mic capsule is far preferable to a dynamic mic, as they are far better in terms of response, sensitivity, noise rejection, etc. It's pretty hard to even find dynamic microphones anymore.

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ghostvet
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Re: CB/Intercom mike

Postby ghostvet » Sun Jun 17, 2012 2:46 pm

Argh! This is killing me!

I have a thing about doing things myself. Plus, I have a big thing about buying stuff that is, to me, way overpriced. Combine the two of these together, and you have me not wanting (nor being able) to spend $200 for good quality but way overpriced headsets and mics, which is essentially nothing more than a mic, two speakers, and some wires.

The mic I am using is really good quality (and really tiny) even tho it is just part of the OEM earphones that came with my Android phone.

I am really frustrated that I cannot get these seemingly simple things to play nice together!

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ghostvet
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1997 GL1500SE

Re: CB/Intercom mike

Postby ghostvet » Sun Jun 17, 2012 2:53 pm

Can anyone think of any product that used a good quality, but tiny, dynamic mic?

Maybe I could find a couple and cut the mics out and use them (two helmets), without spending hundreds?

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ghostvet
Posts: 120
Joined: Fri Mar 16, 2012 8:08 am
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1997 GL1500SE

Re: CB/Intercom mike

Postby ghostvet » Sun Jun 17, 2012 3:06 pm

What about the microphones in the old micro cassette recorders? I have several of these floating around- maybe I could cut one out and use it?

But then, it wouldn't work with the phone, would it?

The phone uses a condenser mic, the bike uses a dynamic mike... Maybe I could fit two mics in the chin of the helmets?

Suggestions?

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WingAdmin
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2007 Aspen Sentry Trailer

Re: CB/Intercom mike

Postby WingAdmin » Sun Jun 17, 2012 5:49 pm

There's no such thing as a tiny dynamic mic. That's the nature of the beast. That's one of the main advantages of condenser mics.




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