Each items number is also the drawing number.
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
Original circuit board
Note modified circuit board with terminal cut outs unused
Capacitor C1 has also been removed - probably used on Plug and Socket
SBM variant - note the simplified rectifier element and lack of capacitors
Telephone-Unit D92744 (Mark 1)
Used on Telephone No. 722
Telephone-Unit D93039 (Mark 1)
Used on Bellset No. 49A
Mark 3 has additional Terminal 19A.
Used on Telephone No. 1/722
Used on Telephone No. 4252
Circuit Board has additional terminal 19A.
Used on Bellset No. 50A & 50C
This board was also miniaturised later in production - probably as a cost
Used on Bellset No. 50B & 50D
Telephone-Unit D93458 (Mark 1)
Used on Telephone No. 776
Used on Telephone No. 782 Mark 1
Used on Telephone No. 782 Marks 2, 3 and 4
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
Use on Telephone No. 756
This is a modified Telephone-Unit D92732 Mark 1.
This is a modified Telephone-Unit D92732 Mark 4.