[Woodsy]

I've acquired a few 2.5mm plugs (4 ring) from my local electronics store and I'm going to create my own headphone/car adapter.
I'd like to know the pinout, pins and/or wiring for the coupler and adapter.

Here's the info I've gathered in my testing:-

Stereo audio (Confirmed):-
Pin 1 (the tip) is Control +2.4v
Pin 2 is Left audio
Pin 3 is Right audio
Pin 4 is Ground
Pin 1 has a 1.4K ohm loading to Ground and the pickup/mute button shorts Pin 1 + 4 momentarily.

Stereo audio + mic (Unconfirmed theory):-
Pin 1 (the tip) is Control +2.4v and Microphone
Pin 2 is Left audio
Pin 3 is Right audio
Pin 4 is Ground
Pin 1 has a 1.4K ohm loading to Ground and the pickup/mute button shorts Pin 1 + 4 momentarily.

Mono audio + mic (Unconfirmed theory):-
Pin 1 (the tip) is Control +2.4v
Pin 2 is Left/Combined audio
Pin 3 is Microphone
Pin 4 is Ground
Pin 1 has a 1.4K ohm loading to Ground and the pickup/mute button shorts Pin 1 + 4 momentarily.
Possibly swap pin 2 and 3.

Can anyone confirm/enlighten me with this?
Any info would be greatly appreciated.

**** Changelog****
[Edit] - After testing this configuration it didn't work as expected...
[Edit2] - After testing again i fixed my initial mistake... (silly me...)

Headphones work perfectly in stereo with a 2K ohm resistor between pin 1+4. The resistor ohm doesn't really matter as long as it's roughly around 1.4K.

After playing around with the adapter I've come to the conclusion that 2.5mm jack plugs are crap, or the socket in the BlackBerry Pearl that I own is of questionable quality. With such a small plug and it's inherently small surface contact area with the socket, any sideways movement or grease on the contacts will give unexpected results when carrying the phone on person. For car audio this shouldn't be an issue in a stationary dock.

Next task is to figure out how the microphone is integrated. My theory with stereo output is that the microphone is connected to 1+4 but the answer/mute button still shorts 1+4. More testing is needed to confirm this.

Will update as I discover more...

[Edit3] - Added Photo. Pretty sexy huh? Not bad for $5au.

[shishi]

Hello Woodsy,

Thanks for your post, I have been searching through the web and except of your note I have found just one unconfirmed message on pinouts.ru...

As you seem succeeded with the stereo headphones adapter I would like to kindly ask you for some help with the same.

My only intention is getting the stereo sound to my headphones from the device and I do not care about the microphone nor play/pause/mute functionalities at all (your confirmed "Stereo audio" option).

So far, I got couple of 4-pole 2.5mm plugs and experimented with them. The problem is that I am getting no signal on pin 3 and getting mono signal (left + right channels together) on pin 2 (do not believe all the connectors are bad). Have you ever met with something similar?
The source mp3 is in stereo so, this is not the problem.

Thanks a lot in advance; any help/idea is appreciated.

shishi

[shishi]

Will answer to myself:

The headphones have to be connected (through the adapter) before playing the media. I was trying different pins while the music was playing which was not a good idea. The above pinnout (stereo audio; not tested the others) works fine.

shishi

[Woodsy]

I was hoping that it was that simple, but had not had access to a PC for some time to post (Graveyard shifts suck).

When trying the first adapter I actually stumbled upon the fact that you need to load pin 1 to 4 by accident. I had wet hands when trying to secure a dry solder and discovered that it worked briefly while pressing down on the solder rather hard. Further highly technical troubleshooting with my own spit and then a variable resistor yielded results... :P

[getmaddy]

Originally Posted by Woodsy

I've acquired a few 2.5mm plugs (4 ring) from my local electronics store and I'm going to create my own headphone/car adapter.
I'd like to know the pinout, pins and/or wiring for the coupler and adapter.

Here's the info I've gathered in my testing:-

Stereo audio (Confirmed):-
Pin 1 (the tip) is Control +2.4v
Pin 2 is Left audio
Pin 3 is Right audio
Pin 4 is Ground
Pin 1 has a 1.4K ohm loading to Ground and the pickup/mute button shorts Pin 1 + 4 momentarily.

Stereo audio + mic (Confirmed):-
Pin 1 (the tip) is Control +2.4v and Microphone
Pin 2 is Left audio
Pin 3 is Right audio
Pin 4 is Ground
Pin 1 has a 1.4K ohm loading to Ground and the pickup/mute button shorts Pin 1 + 4 momentarily.

Mono audio + mic (Unconfirmed theory):-
Pin 1 (the tip) is Control +2.4v
Pin 2 is Left/Combined audio
Pin 3 is Microphone
Pin 4 is Ground
Pin 1 has a 1.4K ohm loading to Ground and the pickup/mute button shorts Pin 1 + 4 momentarily.
Possibly swap pin 2 and 3.

Can anyone confirm/enlighten me with this?
Any info would be greatly appreciated.

**** Changelog****
[Edit] - After testing this configuration it didn't work as expected...
[Edit2] - After testing again i fixed my initial mistake... (silly me...)

Headphones work perfectly in stereo with a 2K ohm resistor between pin 1+4. The resistor ohm doesn't really matter as long as it's roughly around 1.4K.

After playing around with the adapter I've come to the conclusion that 2.5mm jack plugs are crap, or the socket in the BlackBerry Pearl that I own is of questionable quality. With such a small plug and it's inherently small surface contact area with the socket, any sideways movement or grease on the contacts will give unexpected results when carrying the phone on person. For car audio this shouldn't be an issue in a stationary dock.

Next task is to figure out how the microphone is integrated. My theory with stereo output is that the microphone is connected to 1+4 but the answer/mute button still shorts 1+4. More testing is needed to confirm this.

Will update as I discover more...

[Edit3] - Added Photo. Pretty sexy huh? Not bad for $5au.

Thanks, the pinout for handsfree works fine with 8100 pearl

[Semore666]

G'day Guys,

your posts have been very interesting. It has been very helpful enlightenment for myself.

I would like to connect my phone to my snowboarding helmet to double as an mp3 player and easy access phone calls.

Do you think this would be possible??? if not would a cheap 2 ring 2.5 to 3.5 mm adapter simply work to use the pearl as a mp3 player only???

Much appreciation for anyone to could shout out.

PS. I do not have the authentic ear piece that comes with the phone iteself. I'm looking to get something from ebay but am unsure about spending 10 bucks and waiting weeks and weeks for it unless it will work.

Here is a reference to something I was considering on ebay:

(2.5mm to 3.5mm Stereo Adapter + Retractable Headphone - (eBay item 140169117830 end time Oct-23-07 12:10:43 PDT))

regards,
Semore

[hrangil]

Related info FWIW ... today I purchased a "Headset Jack Adapter - 3/32" to 1/8" Wireless Phone" from R.S., part no. 274-004. I had a weird experience in the store, testing the adapter. At first it did not work. Then the sales person offered to try a standard mini-to-micro adapter. That gave me one channel, per my previous experience. While she was looking for other alternatives, I tried the aforementioned part 274-004 again, and voila! it worked. No real clue as to why, at first. Later at home I plugged in my headphones and again it did NOT work. Arg! I experimented with several configs, and finally found the solution:
Step 1: Plug in mono headset or standard micro-to-mini plug adapter
Step 2: Play media
Step 3: PAUSE media
Step 4: Plug in stereo headphones
Step 5: Un-pause media -- voila! Stereo media through headphones.
Now, I suspect this isn't all good for the BB. I suspect it may be shorting the microphone circuit. In between songs I get a little "snap/click" kind of noise. Dunno if that's endemic to the BB's media player or if it's a symptom of electrons going where they shouldn't. But I'm using it in this config and will see what happens.

[davidmkelly]

I bought a 2.5mm to 3.5mm adapter from fommy. co. uk (part number 7905) which specifically stated on their website that it was compatible with the Pearl. I was skeptical but decided to buy it - and not surprisingly when I tried it I found it wasn't compatible. It only worked on one side of the headphones and it kept triggering voice dialling.

I decided to open it up and modify it and would like to thank Woodsy for the info as well as the really helpful pinout info on pinout. ru

I replaced the internals with a piece of vero board with the required 1.4k resistor. At least the 4 pole 2.5mm plug and the 3.5mm adapter were useful.

So I now have an adapter for listening (I didn't want the mic function anyway).

When I told fommy that they were contravening the trades descriptions act when they said that their adapter does work with the Pearl they replied saying that it is compatible!!! implying I was lying or there was something wrong with my Pearl - strange that now I have modified the adapter it works perfectly with my Pearl !

[b-k]

Hi. Thanks for posting this. I wander if you can clarify this (english is not my first language): In the adaptor I need to connect a 1.4k resistor between pins 1 and 4? Thanks!!

[frank-hertel]

A Radio Station brought their Blackberry Pearl to me to interface it with their Remote Broadcast Mixer.
(their Blackberry Pearl used a 3.5MM, 4 contact Jack ).

I was able to get it operational by using the following:

(TIP) = Pin 1 = Electret Microphone High

(RING 1) = Pin 2 = Mono Receive Audio

(Ring 2) = Pin 3 = CONTROL LINE
(No Connection = Dial via Voice Prompt or Dial Normal)
(Connect to Pin 4 = Hang Up / Disconnect)

(Sleve) = Pin 4 = Common


Multi- Function Mode

If you plug in a Standard 3 Contact, 3.5MM Stereo Headphone you wll now have Stereo Audio Playback with:

(Tip) = Pin 1 = Left Ear

(Ring) = Pin 2 = Right Ear

(Sleve) = Pin 3 = Common
NOTE: The longer Sleve of the 3.5 MM Standard,
Stereo Plug,when inserted into the
Blackberry's 3.5 MM, 4 contact jack,
will physically connect the Blackberry's
internal Ring 2 Contact (Pin 3) to COMMON
(Pin 4).

There are likely other functions that are possible too--they didn't bring a manual with the Blackberry so I was flying blind.

In the end, we decided to not use the Blackberry Pearl because it has so much residual system Automatic Gain Control on its audio circuits that it would not perform as cleanly as we desired.

By the way, I used 2 separate 600 to 600 ohm Impedence Isolation transformers between the Broadcast Remote Mixer and the Blackberry connections.
One transformer on the Mic Input Ckt (Pins 1 & 4).
One transformer on the Mono Out Ckt (Pins 2 & 4).
(Ring 2), Pin 3 was not used in our application.

Transformers may not be necessary for all uses, but the transformers do provide ISOLATION and PROTECTION and in Broadcast use this is always the safe thing to do and it also provides a Industry Standard Load for both Input and Output circuits.