This is a Bell Number 56C used by the GPO, Post Office and BT. I saw this on an auction site and couldn’t resist buying it. I’m not sure what I’m going to use it for but it will be wired up to something or other before long.
The bell has two 1000 ohm coils and runs from 10-25 or 25-60 volts DC. Apparently, the coils should be connected in series when the operating current is obtained from the Exchange Line, and in parallel when the operating current is obtained from local primary cells.
The Bell No. 56C is a separate GPO/BT ringer, rather than a complete telephone. It’s an electromechanical DC trembler bell, typically in a black cover, with a 2½-inch gong. It was used as an internal bell in telephone and signalling installations.
The “C” identifies its coil version: it has two 1,000-ohm coils and is designed for higher-voltage DC ringing, listed as 10–25 V or 25–60 V DC. GPO circuit diagram N656 covers the 56C and related 56A bell.
The Bell No. 56 series replaced the older Bell No. 13. Early examples have a wooden base; later ones commonly have a plastic base. The design continued in use across the GPO, Post Office and BT, and examples are dated to at least 1968.
If you have one, the label “56C” is the key clue: it tells you the coil resistance and intended supply range. It doesn’t mean the bell is a 56C telephone. The one I have is a 56C. I hope to connect it up at some stage to work as the front doorbell.