Diagram N640D.C. Trembler bell used on fire alarms.
Bell 40A - Twin 50 ohm coils, 2-10 volts
Bell 40B - Twin 250 ohm coils, 10-50 volts
Uses Bell Gong No. 21, 4.5in diameter x 3.1in Church
Diagram N640
D.C. Trembler bell used on fire alarms.
Bell 40A - Twin 50 ohm coils, 2-10 volts
Bell 40B - Twin 250 ohm coils, 10-50 volts
Uses Bell Gong No. 21, 4.5in diameter x 3.1in Church
GPO Engineering Instructions on Fire Systems
| BACK | Home page | BT/GPO Telephones | A - Z Index | Glossary of Telecom Terminology | Quick Find | All Telephone Systems |
FM