Autocom Earphones Only

jfheilman

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What I want to do is to only use my earphones with my Autocom Pro AVI. I have a helmet that I don't want add the cabling to interface with the Autocom (I want to use the same helmet on multiple bikes, one has Autocom one does not).

Its a 3/4 helmet. I just want to put in the earphones (in the ear speakers for Ear Inc) and plug it into the Autocom somehow. I have the cable with the interface box that i can use which will do that but that leaves a long cable sort of "hanging" around.

Does anyone have an idea or a solution?

BTW, the GPS, and CB are tied into the Autocom along with the radar detector. I can plug into the GPS if I was but I wanted all three audio sources.

Thanks.

Jim
 
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jfheilman

jfheilman

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Mark,

Thanks.. That appears to be the exact doodad I was looking for... I will have to call and confirm, since its for five, seven or eight pins and I have to assume that it has five and the five are arranged to they fit in all three types...

Jim
 
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jfheilman

jfheilman

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Got the doodad yesterday and while it worked (that is plugged in) the audio level was too low to use with the Autocom system. I will check it with another system (on a Goldwing) to see if it works there. I am now back to Plan B.
 

Blrfl

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If the output from your Autocom is fine in the helmet with the Autocom headset, the problem's more likely the headphones rather than the adapter.

Headphones and speakers have a figure called impedance, which is the amount of resistance they present to AC current. Your Autocom was designed for use with the Autocom headset, which has an impedance of 32 ohms. If you connect headphones with a higher impedance, the additional resistance means less current can flow through them, resulting in less volume.

Check with whoever you made your headphones, but if they're good ones, they probably have an impedance north of 100 ohms. Less-expensive earbuds tend to be designed for lower impedance so portable gadgets like mobile phones and MP3 players can drive them without consuming a lot of battery. There are a bunch of reasons there isn't a standard impedance that I won't go into here.

--Mark
 
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jfheilman

jfheilman

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Mark,

Thanks. I understand. So, I have an Autocom helmet headset, you know for interfacing the mike and background noise sensor to the Autocom unit. The earphones work with that interface. I also have an Autocom cable with the inline headphone adapter. So, I plugged in the cable to the Rider Autocom lead and plugged in the headphones, worked as expected (the headphones, in the ear speakers, are from Ear Inc and the helmet was not attached to the rider cable).

Therefore, by process of elimination the interface plug (doodad) must be the culprit. I have some schematics of that in-line interface and it appears that the interface has two reistors and two capacitors in line with the audio signals. So, Play B is to build one, looking just like the one that works. Plan C is to use the Autocom interface cable with the little box for the headphones until I get it built.

In years past I would have built the doodad at the beginning, having all the information i needed at hand just had to reverse engineer it. But, as I get older, I find that either I get lazy or want more instant gratification.

The symptoms are interesting (for the record). When I plug the headphones into the Rider lead (using the doodad), I get a loud clunk noise, as if the volume will be high. You know the sound when you connect an audio device to a live system. But the resulting actual audio level is very low. At first I thought I might have gotten the Rider volume control moved when I reinstalled the system. But when I plugged in the Rider lead (not attached to the helmet) and plunged in the headphones, the audio was at the expected level.

Just for the record, I have called the things in my ears, earphones, in the ear speakers, and headphones. So.. Is there a standard definition? For instance, earphones and in the ear speakers seem to be specific. Up until recently I used the earphones for Ear Inc that have the audio component down on the lead running the acoustics through a coiled hollow in to the earpieces.

I ordered a new pair earlier this year, again from Ear Inc and they talked me into getting the devices that have the audio component in the ear plug itself. So I guess those are in the ear speakers.

Jim
 
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Sorry the doodad did not work. I would like one also.

I know that if you did not resistor down the autocom to earphones they would be extremely loud. Not sure why the capacitors are used but I am sure there is a good reason.
 
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jfheilman

jfheilman

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Well when I get it made, found, etc, I'll post the info here along with the comparison...

Capacitors are generally used as blocking devices. In this case they probably are used to block DC and only allow the audio signal to pass (ac). Autocom likes to use transformers in their interface circuits but for small applications with known devices, the simple way is best and more economical...

My best guess
 
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ST Gui

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Is this http://earinc.com the place your talking about? E.A.R. Customized Hearing?

Generally speaking headphones headsets and earphones have direct coupling to the ears. Earphones go in the ears and some go in the ear canal itself. Headphones go on or around the ears and are mounted together as a single unit. Headsets are headphones (and now earphones too) with a built-in mic.

Speakers have no direct coupling to the head. "Ear speakers" is a marketing term. I first heard it used in reference to some Stax headphones IIRC. But they were still worn on the head and rested against the ears.
 
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jfheilman

jfheilman

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Yes that is the place. And thanks for the information. So, I have earphones.... Or at least the most recent ones are for sure. I have really enjoyed by earphones from them. I got the first set through Arizona Al who I meet her on the forum..
 
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jfheilman

jfheilman

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Ok, so based on a diagram of the Autocom 7 pin interface cable with the headphone jack, I built a working doodad. The only problem is it needs a case. Cost for parts, less than $10. I got the parts from Newark when ordered a new heat gun. Still shipping costs were rather high.

I could only find the seven pin DIN plug from them.

Here is a pic.

Ok the picture is upside down and I have no idea why... I took it right side up :)

(Turned photo right side up. Byron)
 

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jfheilman

jfheilman

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Update. Doodad continues to work as needed. Audio is clear and clean. Am working on a backup but will just do the parts in-line like the Autocom helmet lead.
 
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jfheilman

jfheilman

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Yep, I have not looked at the internals of that (I have two of them in separate helmets) but the second version is going to look like that with heat shrink tubing sealing the components in line . While I am not positive, I bet they have the same components in that little black thingy at the end.

I would have had it already done but I got a new heat gun and it has two levels. I put it on high to shrink the tubing before I did some final assembly and it melted the plastic cover on the 3.5mm jack. Plugs are easy to find, jacks are not so easy.... (unless I make another order).
 
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jfheilman

jfheilman

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