# building your own clearcom/telex head set



## koncept

I am working at about 3 theatres right now all use a different intercom system and all have headsets that are falling apart. i wnat to build my own using a $20ish computer headset & mic using an adapter. a 4 pin xlr to two 1/8" jacks. I want to know if this would work or not. if so does any one have some advice??


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## sandals1621

Yes it will work. I've know several people who buy a small computer etc headset mic combo and change it to a 4pin XLR. 
You just need to know the pin-out for the headset you have and the corresponding pin-out of the com system.


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## JahJahwarrior

So, in a 4 pin XLR headset jack, it's probably hot and neg for headphones and mic? Could they use the same ground (neg)? I know alot of cheap cell phone headsets have 3 conductors, so I'm assuming that's what they do.


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## koncept

i found a few sites with the pinouts for both the telex and clearcom systems. the pinouts are the same which is nice. correct about the pos and neg for ears n mic. i do not know about using a cell headset all though taht would be idea as I already have one i like


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## JahJahwarrior

I think you could use one. Is there any reason to have seperate grounds for headset and mic?


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## jumpjet

I think the call light on the clearcoms is an induced short across 2 pins....


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## koncept

only reason i can see for separate grounds if if the mic n speaker are on different voltages. thanks for the info jumpjet. i will pull up the diagrams later and post the pins.


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## LX-88

hmm..... Bluetooth headset.

http://www.gnnetcom.com/US/EN/MainMenu/Products/Wireless+Solutions/GN+6210.htm

Would the above technique work for a phone line?

Phone line to XLR?


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## koncept

I wish it would, but i dotn think so....*frowns*


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## jumpjet

Hrm. Possibly. It claims that with the base station/headset combo, you can use it with "Any" phone, bluetooth compatible or not. It probably plugs into a phone where the handset would... Which means it would probably work with the right wiring. Expensive headset though, just for telling the spotlight operators to quiet down....


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## jumpjet

Yeah, here is a pic from the manual. The base station takes the place of the handset, or rather, piggybacks in between, so I'm almost certain you could make this work...


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## koncept

if thats true, then get the pin outs for a handset and you should be good.


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## Andy_Leviss

You can't use a cell headset, as you MUST have separate grounds for the earpiece and mic...otherwise the sidetone null won't work properly, and you'll have feedback issues, among other things.

Also, to use some computer headsets (and cellphone headsets, were the separate reference grounds not an issue) you need bias power for the electret mic, which is an optional setting that needs to be changed on the circuit board of the ClearCom pack, or provided in the connector/an adaptor box via a circuit you build.

--A, resident ClearCom guru


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## LX-88

So with that in mind. Is anyone willing to write a tutorial to do this?


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## koncept

If i build mine this week i will write a tutorial and parts list.


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## LX-88

Could someone give me a brand name / model for a headset that would work? Is it any computer / phone headset? The whole grounding thing scared me. I have shows on Thursday, Friday, and Saterday and I would love to get one or two built before those.

I don't want to blow up the clearcom system so some guidence would be great.


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## LX-88

Ok. So I found a headset around the house that is a Panasonic KX-TCA86. It had a 2.5mm plug on it.

Product Page is: http://www2.panasonic.com/webapp/wc...rogram=11002&cachePartner=7000000000000005702

I found this page: http://www.epanorama.net/links/intercom.html#fullduplexintercom

That says:
The beltpacks on Clear-Com system use typically a headset that is connected with a 4-pin XLR connector. The dynamic headset connector pin-out is:

Pin 1: mic common
Pin 2: mic hot
Pin 3: headphone common
Pin 4: headphone hot

Now that I have cut off the plug I have 4 wires:
1 Red, 1 Green, 1 Gold, and 1 White

The red and green ones have a nylon looking material wound into the wires. I would assume that that means they are paired together.

My question is: Are the red and green the mic or the speaker? and which color is ground, because ground isn't black.

Thanks for your help


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## SketchyCroftPpl

I couldn't find this anywhere on the web, but I was wondering if anyone knew the pin order inside the 4-pin XLR cable. I know that they have number from 1-4 and probably go in some sort of logical order, but I couldn't find it.


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## koncept

the pin order for the xlr is posted above


> The beltpacks on Clear-Com system use typically a headset that is connected with a 4-pin XLR connector. The dynamic headset connector pin-out is:
> 
> Pin 1: mic common
> Pin 2: mic hot
> Pin 3: headphone common
> Pin 4: headphone hot


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## SketchyCroftPpl

Its not that which I don't understand. its that inside the physical wire there is an order of pins like

.------.
.---.


How are they numberd? is it 1,2,3,4 from left to right if you are looking at the wire like that, or is it like that if the wire is flipped over from as its shown here? or how exactly is it define.

(The dashes were Added only to keep the spacing correct, only look at the dots please.)


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## LX-88

I got mine built last night, so I will try it today and let you guys know how it went. Ill try and post a tutorial type thing but I don't know how good that will be.


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## Andy_Leviss

On a female XLR connector (as used on a CC compatible headset), the "pins" looking at you, the numbers go clockwise from the upper right, so:
4--------1
---3--2---

On a male XLR connector (as for Telex/RTS), they go counter-clockwise.

If you look real closely, the numbers are molded right next to the pins on the connection side of the connector (ie, not the side with the solder cups).

--A


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## Mayhem

The numbers should be on the solder side as well - certainly all of the XLR connectors that we get are.


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## LX-88

One guy i was talking to last night said that positive and negative didn't matter. But when I tried my headset today it didn't work. I know I put the wires in the right spot, just maybe got the positive and negative mixed up.

Is my friend right? Positive and Negative don't matter? Or did I screw up somewhere else?


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## SketchyCroftPpl

I think they do matter, because the box for the headset is expecting the inputs on a certain channel so if you switch that, it won't be looking to the right spot. It may not matter it seems on a 3-Pin XLR where if you look it up and its just a peaker I believe or a mic there are more than 1 way that you can wire the ground and the hot, but it would seem that switching them where you have a mic and a headphone speaker would make a difference.

Box 1 is expecting voice in over pin 1 so it can send it out to box two over pin 3 but if the voice comes in over pin 2 it sitts there waiting for it to come in and nothing happens. Ask your friend specifically what type of wire he means.

~Nick


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## koncept

As mentioned abouv it could need an additional power supply for a portion of it. with the speaker it should not matter positive or negative, but with the mic it might


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## Mayhem

You may have the mic/speaker wired around the wrong way, which will certainly cause problems. Either that or the impedance is different between the headset and the com system


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## SketchyCroftPpl

Has anyone taken apart a old headset of theirs that was broken and looked inside of the plug to see if the wires are the same color or give any type of hint to the correct pattern which should be used? It may be very useful.

~Nick


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## koncept

I have a parts one up at the college. I will try and take a look tommarow.


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## LX-88

I was looking at my cr*py job of sodering and noticed one of the ground wires touching the live wire, wo with that said I am going to try my headset once more to see if it works.

I'm hoping that it will work.


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## SketchyCroftPpl

That would be awesome, is there any chance you could take a picture of the internals of the plug or anything? Our headsets are wicked crappy and falling apart and my TD REALLY liked the idea of being able to build some new ones, but I want to have a clear idea of what I'm asking him to let me try before I propose taking home the headset and actually doing it to a new one.

~Nick


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## koncept

You don't need to destroy a new one. buy 1 male (i thinK) 4 pin xlr plug, some say 16-18 gauge stranded wire and 2 female 1/8 jacks create an adapter to be used with the computer head sets....


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## SketchyCroftPpl

Good Idea. This is a more random question but how do you make the text where if you scroll over it, it shows you a question mark and will give you the deff of the word, it seems very usefull.

I'm trying to cut out having to order anything, and our headsets are seriously so shot to hell we have ones handing on the wall I don't even know why because the speaker plate is gone, mic is hanging, and you can't see or hear anything. plus then I've got extra cable and the plug, I just wonder how hard it will be to disconnect the old connections from the pins.

~Nick


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## koncept

some words are done automaticaly by the forum. if you have old headsets to be thrown out take the cord and cut it about 18 inches from the plug and just solder on your new plugs.


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## SketchyCroftPpl

So your saying, *I'm on 5 hrs of sleep and 4 hrs of rehersal with noisy 8th gradaers* instead of actually re-wiring the plug it may be easier to simply cut the wire and cut the end off of the new headset and then solder the old wired to the new wired and then use tape or w/e over the connection?

~Nick

EDIT:
Just an afterthought, has anyone actually done this and gotten it to work yet?


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## koncept

no keep the new set the way it is, cut the old one, and add 2 new 1/8 jacks to wire 1 & 2 and one to wires 3 & 4

one jack will be mic the other will be speaker


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## LX-88

you mentioned two 1/8 jacks. the headset i cut apart only had one w/ four wires in it....

I think I used the wrong headset. Ill try it again though just to make sure.


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## SketchyCroftPpl

Do you mean an old headset or a new computer headset? On some of the newer computer headsets they have all the connections leading down to one plug instead of two like on the older ones I have.

~Nick


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## koncept

the 1/8 jacks were for a new computer headset (that has a separate mic and audio plug) to plug into the 4 pin xlr


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## LX-88

So would one of the computer headsets that has one pin work? Or am I scewed?


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## koncept

if it has separate ggrounds for both the audio and mic then it should work fine.


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## LX-88

So has anyone sucessfully made this thing work?

I'm gonna make a box that has a place for the the battery too.


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## SketchyCroftPpl

That looks pretty sweet, can you post a list of what you did / used to make that box? It looks very professional. (Tell me if I'm wrong and thats the actual headset box which came with the system).

~Nick


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## LX-88

I think that's the box that contains the battery and resister thing. Is the switch to turn the power on and off?

Please write a tutorial of how you did it, and the parts that you used. I would love to build a clone of what you did.

Did you build the headset as part of the unit or is it seperate?


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## Aaron_Parsekian

Well unfortinately the circuit I posted didnt work  Well, it did sortta, just not enough gain.

I'm gonna try another simple circuit that uses an LM386 audio op amp IC, so we'll see if that does the trick.

Its hard for me to test this stuff cause I have to break into my schools auditorium to test it on our clearcom setup, I wish I had a setup at home .

I'll try to post updates asap


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## koncept

thanks aaron. it looks great. if it the chip works i dont need to use our schools crap....


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## LX-88

thanks aaron. I am really looking forward to not being forced to use my schools uncomfortable headsets and be able to afford my own setup.

Would you be willing to post pictures of the inside of your box as well as a circuit diagram (once you get it fixed?

Another thought. How dificult would it be to incorperate a small LED to tell if power is on or off from a distance?


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## Aaron_Parsekian

It would be very easy to add an led. I promise all of you I will do my best to get this to work and that when I do get it to work I'll post a guide on how to do it. I really want this headset to work.

Just so you all know, the circuits involved with this are VERY simple and easy to make. You can get all the parts at radioshack.


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## koncept

if the switch is for power then it should be very easy to incorporate a led. I would not reccomend adding one as that is just another item to drain the battery....but leds do not draw that much so it shouldnt be a big deal.


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## ralxz

Yeah. LEDs barely use any battery, but it's still some. The best way to go is to get rechargable batteries, though. They save you so much $$$ nowadays.


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## koncept

i havent had a chance to look the clearcom system diagrams over, but could you draw power from there to say its on or off and change the switch to be a double pole single throw.


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## Aaron_Parsekian

Okay the circuit I posted actually DOES work. I put a dead 9v battery into the circuit instead of a good one.  Hey everyone makes mistakes!


I'll post a guide tomorrow with pictures. Here is a quick parts list:

220 Ohm 1/4 watt resistor

10uF capacitor

9v Battery

Enclosure

4pin XLR connector (female)

ON-OFF switch for battery (SPST)

Again, all of this can be purchased from radioshack, tomorrow I will provide radioshack part #'s and pictures guiding my assembly of this circuit.



I do hope some others can build and test this circuit cause I'm not sure how loud its output will be compared to standard clearcom headsets


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## LX-88

I'm looking forward to the tutorial. How much was the whole thing do you figure?


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## Aaron_Parsekian

about $9-10 not including headset.


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## koncept

I plan on building a modified one, but it will follow the exact same ciruit diagram. instead of hardwiring the headset in I will be using 1/8 jacks and i am thinking about including a mute switch only because of how our theatre is set up....(there are about 4 feet between the headset wall plate (no belt pack in this spot) and where you need to be to use the headset)

thanks aaron, can you approximate how loud it is? as in soft or loud


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## LX-88

I am going to use 1/8" jacks too, as well as add a LED to the mix. I would be interested in how you put the mute switch in.

Here is my parts list at the moment ( I havn't put it together yet because im waiting for the tutorial, nor have I purchased anything):

DPDT Rocker SwitchRed $3.99
www.radioshack.com/product/index.jsp?productId=2062525

Project Enclosure4x2x1" $2.69
www.radioshack.com/product/index.jsp?productId=2062280

1/8" Stereo Panel-Mount Phone Jack $2.99 (two of them)
www.radioshack.com/product/index.jsp?productId=2103451

Heavy-Duty 9V Snap Connectors $2.59
www.radioshack.com/product/index.jsp?productId=2062218

9-Volt Battery Holder $0.99
www.radioshack.com/product/index.jsp?productId=2062220

225-Ft. UL Recognized Hookup Wire 22AWG $5.49
www.radioshack.com/product/index.jsp?productId=2049745

Red LED with Holder $1.99
www.radioshack.com/product/index.jsp?productId=2062561

220 ohm 1/4W 5% Carbon Film Resistor pk/5 $0.99
www.radioshack.com/product/index.jsp?productId=2062340


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## Aaron_Parsekian

Thanks guys, I'm not sure how loud its output is cause I havent tested it on a clearcom system, I've only tested it by pluging it into a single pack connected to a 24v power supply


It would be great if someone here who has more access to a clearcom setup could test it.


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## koncept

I have the access and sdhould be able to try it after break. the mute switch in theroy would work by breaking one leg of the mic. i am wondering if the switch that is there for power would work as well though???


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## soundlight

Avoid Radio Shack if you can. Buy from Jameco. I make circuits for a hobby, and I get my parts from Jameco. You can get everything but the project box for less, and you can even get the XLR connector there, so you don't have to cut any headsets. Works really well.

http://www.jameco.com

P.S. Don't have clearcom or I would have tried this as soon as the topic popped up...I like projects like this...but it's a really good idea. I wish that I could build and test one.


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## Andy_Leviss

You don't want to make the mute switch break one leg, since there's power to the mic, that would cause it to pop. What you want is to use a NO switch ACROSS the two mic lines, so that when you press it, it shorts the two lines together. This will eliminate any popping and mute the mic.

--A


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## Aaron_Parsekian

I think that the output isnt loud enough. I found two old telex beltpacks and daisy chained them together and powered them with a 24v power supply. The headset I made was a little on the low side compared to the telex headset.

I think adding this circuit to the design would maybe help:


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## koncept

its a thought....

edit: i am going to try thr original on our system...if it doesnt work i will try adapting it to this design


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## LX-88

Is there any easy way to add a knob to control / change gain like on a sound board? I would think that if you were using different headsets the gain might change. It would be nice to be able to change that.

Correct me if Im wrong


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## koncept

I think you got the right idea, but i am not good with electronic circuits so i cannot say how to do it. I'm sure it would make a little difference.


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## AVGuyAndy

LX-88 said:


> Is there any easy way to add a knob to control / change gain like on a sound board? I would think that if you were using different headsets the gain might change. It would be nice to be able to change that.
> 
> Correct me if Im wrong



Why not just use the clearcom pack volume control?


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## SketchyCroftPpl

Hey, this may be a stupid question but I don't really do anything this complex for electronics. For our theatre we have a good set of working boxes and the fact that you need them makes me thing that this may be some other type of system. I can look it up once we go back and then ask some other stuff, but I just wanted to know, if all I wanted to do was replace the headset part which has the 4-Pin XLR on the end I could just make the 4-Pin XLR Cable to two female mini jacks just so that I could plug it into the working box correct?

~Nick


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## SketchyCroftPpl

Hey All

For anyone who is having trouble understanding all the stuff about the circuit digrams and all that and the things about the pieces and parts, go check out the new post under general discussion called "Amazing Circuitry and Hardware Website". Read the post and it tells you where to look for explainations about it all. It helped me alot anyway.

~Nick


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## LX-88

SketchyCroftPpl said:


> Hey, this may be a stupid question but I don't really do anything this complex for electronics. For our theatre we have a good set of working boxes and the fact that you need them makes me thing that this may be some other type of system. I can look it up once we go back and then ask some other stuff, but I just wanted to know, if all I wanted to do was replace the headset part which has the 4-Pin XLR on the end I could just make the 4-Pin XLR Cable to two female mini jacks just so that I could plug it into the working box correct?
> 
> ~Nick



This doesn't replace that box, but rather turns a computer headset into one that you can plug into the clear-com boxes. You have to power the mic to get it to work. The box in this thread contains the battery and circuitry to make the mic work.


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## SketchyCroftPpl

Ohhh alright. With all the things like the on off switch and the mute button and such it was really starting to take the form of the boxes that we plug the headsets into so I wasn't sure.

~Nick


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## LX-88

On-Off switch is to turn power off you your not replacing batterys all the time. The mute switch im still a little fuzzy on, but I think it's purpose is to mute the mic if the person using the headset is too far away from the wall panel to reach it.


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## Aaron_Parsekian

koncept said:


> I think you got the right idea, but i am not good with electronic circuits so i cannot say how to do it. I'm sure it would make a little difference.



This is exactly what I want to achieve. I will try to assemble the circuit pictured above and add a gain control to it. It should work.


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## LX-88

Any updates over the weekend?


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## Aaron_Parsekian

Yes. I purchased the parts to make the simple audio amp from the schematic pictured above. I will test it tomorrow night.


Pic: Sorry for blurriness


click to enlarge:roll:


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## SketchyCroftPpl

Kinda of an odd question. Is this a headset that should work with pretty much all kinds of systems that would take a 4-Pin XLR headset? Or is all this work going to one specific type of kind like a clearcom or something? I dunno what type of system we have but should it make a big difference? 

~Nick


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## Aaron_Parsekian

Clearcom is somewhat of a standard for other systems. The short answer is yes, if your system accepts a 4pin XLR in probably follows the clearcom standard.


Systems I know of that work with clearcom are Telex and Production Intercom, there are probably more.


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## LX-88

How'd the test go Aaron?


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## Aaron_Parsekian

No go  I'm gonna ask a few friends who have more technical knoledge than me


I hate building crap that doesnt work :x


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## koncept

do you have any ideas why it doesnt work?? I agree it does suck when that happens. But as always thanks for the update


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## Aaron_Parsekian

I think the audio amp IC I'm using has too much gain, I emailed a friend with the problem, so we will see what he thinks.

Sorry to let you all down, this stuff is pretty frustrating! But I'll stick with it till I find a solution.


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## LX-88

As I mentioned before what about adding one of these guys?

http://www.radioshack.com/product/i...&cp=2032058.2032230.2032275&parentPage=family

BUT, I also wanted to say thank you for attacking this project the way you have.


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## koncept

it looks like there is one on the board that is shown in the picture.


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## Andy_Leviss

Aaron,
You say you're testing with a 24V power supply. Is this a real Telex/ClearCom supply, or just a 24V DC power supply applied straight to the beltpacks, or a homemade com supply?

If either of the latter two, it could be improper termination. For a ClearCom system to work properly, you need to have a termination resistance of 4k ohms between pins 1 and 3, or things get wonky. Too high a resistance and you'll tend to get low volume and failure of the sidetone null (possibly resulting in feedback), too low a resistance and you'll usually get feedback and weirdness such as the call light latching for 2-4 seconds and then fading out rather than going right out when you release it (this is on a ClearCom system; on Telex, the call signal works differently; since the systems are compatible, the termination resistance should be the same or darn close).

--A


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## Aaron_Parsekian

Andy_Leviss said:


> Aaron,
> You say you're testing with a 24V power supply. Is this a real Telex/ClearCom supply, or just a 24V DC power supply applied straight to the beltpacks, or a homemade com supply?
> 
> If either of the latter two, it could be improper termination. For a ClearCom system to work properly, you need to have a termination resistance of 4k ohms between pins 1 and 3, or things get wonky. Too high a resistance and you'll tend to get low volume and failure of the sidetone null (possibly resulting in feedback), too low a resistance and you'll usually get feedback and weirdness such as the call light latching for 2-4 seconds and then fading out rather than going right out when you release it (this is on a ClearCom system; on Telex, the call signal works differently; since the systems are compatible, the termination resistance should be the same or darn close).
> 
> --A




Wow, thank you so much, I couldn't figure out why I was getting oscillation.

Nonetheless the headset I'm making currently is noticably lower than the telex headset I've been comparing it to.


Still, I owe you one man!


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## Andy_Leviss

Yeah, improper termination will definitely cause oscillation--in fact, that was the one symptom of it I forgot to mention explicitly ) It's also probably the least known/understood part about setting up a ClearCom system.

My website's currently still down thanks to the hackers, but as soon as I finish restoring the backup (it's a slow process due to my current net access situation) I'll post a link to my guide to common ClearCom troubles, which has links to a couple great free guides online that you should definitely check out (in fact, everybody who ever sets up or troubleshoots a com system should read 'em cover to cover).

--A, resident ClearCom guru


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## Aaron_Parsekian

PM me when it goes back up, I'd love to learn as much as I can about clearcom systems.

Still awaiting a reply from my audio tech friend. . .


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## LX-88

Hey aaron. Any updates? I have one or two people that I could ask about this but I have no ideas what questions to ask / where your project stands. If you want to PM me with the questions I could try and pass them on.

Thanks.


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## Aaron_Parsekian

LX-88 said:


> Hey aaron. Any updates? I have one or two people that I could ask about this but I have no ideas what questions to ask / where your project stands. If you want to PM me with the questions I could try and pass them on.
> 
> Thanks.



Yea, the guy I emailed me hasn't responded (he's very busy) Here is a copy of my email. If any of you could ask someone you know, it would be sweet!!!! 

You could prolly just show them the copy of my email

Thanks!!!!


> Hey Brian,
> 
> I had a quick audio question for ya. I've been trying to get an electret microphone to work with a clearcom system with no luck. This is the schematic I tried: http://photobucket.com/albums/b194/4077hawkeye/?action=view&current=schem.jpg
> 
> Didn't work.
> 
> So my question is how do you convert a 3K Ohm microphone to have an impedance of 200 Ohms (cleacom's standard)? Should I try a simple single transistor pre?
> 
> Ug, Impedance is just one of those things I never fully understood, any help / info you could give would be greatly appreciated.
> 
> Thanks man!
> 
> Aaron
> 
> --
> Aaron Parsekian KC2IAF
> Aim: h4wkeyepierce
> 
> Pictures! http://photobucket.com/albums/b194/4077hawkeye/


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## LX-88

I'll pass that along to my contacts. Thanks


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## LX-88

Wow, I'm bringing this back from the dead. My friend found a site that has directions to doing this. My contacts never came through and I still want my own headset. Ill look up the link and pass it on to you guys


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## koncept

Thank you. I am about to start three shows so I need to get this built soon


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## LX-88

Here's the link:
http://www.matgoebel.com/headset/headset.htm


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## Mayhem

Looks pretty good but I think that I would prefer to place the 9V and the circuitry into a small plastid box that would act as a belt pack. Here you could actually add a PTT button and volume control. 


I am not sure that having a 9V swinging in the breeze is a good idea. Firstly the battery will either catch on something and sooner (rather than later) the wires will break. Secondly, working with pyro, the last thing I want is a battery out in the open!

So for a few bucks extra I would but a small plastic project box and a belt clip.


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## koncept

i agree about the battery, but it looks good thanks guys


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## LX-88

I agree on the box. If someone gets this working, post your experiences.


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## Hermineko

I had a friend who was an engineer use all of the things listed; a headset I "borrowed" From Borders, and an old clear com headset from my old high school and put them together to create an awesome around the back of the head/lightweight headset. The only problem I have come across is that the gain on the mic on the headset cannot be adjusted, and when the beltpack does not have that option either, I can't use it without creating feedback on the system. Any ideas? Or do I just have to use a terribly big headset when using a system without gain control?


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## Chris15

You may not be able to get at the gain control, but wouldn't you achieve the same result by placing an attenuator between the headset and the input?

Assuming an unbalanced headset, which most are, grab a single gang pot and wire ground to (looking from the front) the left, headset mic to the right and beltpack mic in to the centre. Probably something in the region of 10k would be about right. Will have issues if the mic needs bias power though...


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## Jay Ashworth

I was looking for the pinout for the YC-36 adapter for the RS-602, and didn't find it hear, but I want to exhume this thread long enough to put in a link for the altogether excellent "Handbook of Intercom Systems Engineering", written (at 172pp in length) by a top guy at RTS, but applicable to all types of PL systems, and freely downloadable.

If you're plinking around with comm systems of any type to any depth, you *really* oughtta read this book, it is both informative and entertaining.

www.rtsintercoms.com/us/rts/file?i=97123&lg=eng


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