D Types

Each items number is also the drawing number.

Telephone-Unit D92732
Used on Telephone No. 746 (Drawing 92773 and Circuit diagram SA 10116)
On later boards T19A, T19b and T2A are only fitted if required by a circuit diagram

Original circuit board

Note modified circuit board with terminal cut outs unused
Capacitor C1 has also been removed - probably used on Plug and Socket variant

SBM variant - note the simplified rectifier element and lack of capacitors

Mark 1

Mark 3

Mark 4

Telephone-Unit D92744 (Mark 1)
Used on Telephone No. 722


Telephone-Unit D93039 (Mark 1)


Telephone-Unit D93044
Used on Bellset No. 49A
Mark 3 has additional Terminal 19A.


Telephone-Unit D93050
Used on Telephone No. 1/722


Telephone-Unit D93089
Used on Telephone No. 4252
Circuit Board has additional terminal 19A.


Telephone-Unit 1/D93315
Used on Bellset No. 50A & 50C
This board was also miniaturised later in production - probably as a cost saving exercise.

Telephone-Unit 2/D93315
Used on Bellset No. 50B & 50D

Telephone-Unit D93458 (Mark 1)
Used on Telephone No. 776


Telephone-Unit D93937
Used on Telephone No. 782 Mark 1


Telephone-Unit D93883
Used on Telephone No. 782 Marks 2, 3 and 4


Telephone-Unit D94224
Used on Telephone No. 746C

This circuit board has additional terminals 19A and 19B
and also used a Micro-Circuit D4529
Circuit diagram SA 10219


Telephone-Unit D95204
Use on Telephone No. 756

Mark 1
This is a modified Telephone-Unit D92732 Mark 1.

Mark 2

Mark 4
This is a modified Telephone-Unit D92732 Mark 4.


BACK Home page BT/GPO Telephones Search the Site Glossary of Telecom Terminology Quick Find All Telephone Systems

Last revised: February 11, 2023