BUZZER No. 33A
This is an electronic buzzer used in Switchboards 2/-, 3/- and 4/-, which was also used for general purposes.

The circuit also changed over the years - see pictures below.

Mounted by means of a Clip No. 91C (Drawing - 92372) - see pictures below.

There is a Mark 1 and Mark 2.  The Mark 2 was introduced in 1973, but it is not obvious what the change was.  The printed circuit board layout changed on numerous occasions.

Adjustable for 24-50 volts DC.

Introduced 1965.

Drawing - 92305.

Diagram - N649.

Specification - S925.

 

 

Clip No. 91C with a Buzzer No. 33

 

Clip No. 91C with a Buzzer No. 33 fitted in the clip

 

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

Last revised: July 30, 2025

FM