UK Vintage Radio Repair and Restoration Discussion Forum

UK Vintage Radio Repair and Restoration Discussion Forum (https://www.vintage-radio.net/forum/index.php)
-   Vintage Telephony and Telecomms (https://www.vintage-radio.net/forum/forumdisplay.php?f=111)
-   -   GPT Reliance E Link 101 telephone (https://www.vintage-radio.net/forum/showthread.php?t=167010)

Sparks 21st May 2020 12:06 pm

GPT Reliance E Link 101 telephone
 
2 Attachment(s)
I dismantled the handset on this old phone yesterday and was struck by the amount of circuitry built into the microphone compartment. Underneath it all is a simple 2 wire elecret microphone, using surprisingly bulky wires to connect it to the circuit board. Does anyone know what this circuit board actually does ? It it an amplifier to bring the mic output to carbon level or something else ? I've never seen a telephone handset quite like this. I did consider that in other telephones this sort of circuit might normally be found within the telephone body rather than the handset. There is 7 volts going from the main phone circuit board via the handset cord to said circuit.

Thankyou. It's quite a curiosity (to me anyway).

OscarFoxtrot 21st May 2020 1:14 pm

Re: GPT Reliance E Link 101 telephone
 
I can't trace the IC number.

The wires on an electret mic capsule must be kept very short to avoid interference, so it's normal for there to be a preamplifier very close. In GPO/BT phones with an electret transmitter the mic and the preamp are formed together in the transmitter.

Sparks 21st May 2020 3:23 pm

Re: GPT Reliance E Link 101 telephone
 
1 Attachment(s)
The IC number is ST LS656B 98921. Thanks, OF.

Sparks 21st May 2020 3:42 pm

Re: GPT Reliance E Link 101 telephone
 
1 Attachment(s)
A slightly better picture. The white, red, green and black wires on the left are from the handset cord. At the top, the yellow wires are for a mic muting button, red and black for the mic itself and grey for the earphone.

Sparks 24th May 2020 1:30 pm

Re: GPT Reliance E Link 101 telephone
 
I've found out a little about the IC, if nothing else. It has something to do with Texas Instruments and is for telephony purposes. Lots of diagrams available to download which are beyond my understanding! That's all.

dazzlevision 24th May 2020 1:32 pm

Re: GPT Reliance E Link 101 telephone
 
Quote:

Originally Posted by Sparks (Post 1251454)
I've found out a little about the IC, if nothing else. It has something to do with Texas Instruments and is for telephony purposes. Lots of diagrams available to download which are beyond my understanding! That's all.

The IC is branded "ST" = SGS-Thomson, a French-Italian company, now known as ST Microelectronics.

dazzlevision 24th May 2020 1:38 pm

Re: GPT Reliance E Link 101 telephone
 
1 Attachment(s)
Here is the opening description in the SGS data:

Sparks 24th May 2020 1:59 pm

Re: GPT Reliance E Link 101 telephone
 
Thankyou dazzle.


All times are GMT +1. The time now is 3:34 am.

Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.