View Single Post
Old 01-22-2009, 11:23 AM   #10 (permalink)
New Member
Join Date: Jan 2009
Model: 7100T
Carrier: Verizion
Posts: 1
Post Thanks: 0
Thanked 0 Times in 0 Posts
Default Multi-Function on 4 Pin Plug is a possibility

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.

Last edited by frank-hertel : 01-22-2009 at 12:04 PM. Reason: Clarify one statement
Offline   Reply With Quote