Bulle electric clock

From Object Wiki

Bulle electric clock
Manufacturer	Professor Marcel Moulin and M. Favre-Bulle
Production years	20th century
Production location	(unknown)

An electrically driven clock invented by Professor Marcel Moulin and M. Favre-Bulle about 1920.

[edit] How it works

The pendulum carries a solenoid moving over a curved bar magnet with consequent poles, north-seeking in the middle and south poles at the ends. A current from a cell passes through the coil during part of alternate swings, and the interaction between this current and the magnet supplies the impulse necessary to maintain the pendulum in vibration. A pin near the top of the pendulum engages with a forked lever and completes the electric circuit, one side of the fork consisting of conducting metal and the other insulating fibre. By means of a pawl the forked lever propels a crown ratchet wheel which is connected with the hands by worm gearing. The motion of the coil in the magnetic field generates an electro-motive force in opposition to that of the cell and consequently the larger the arc of vibration and the quicker the motion of the coil at the middle of its swing, the smaller the current passing form the driving cell. For the purposes of eliminating the circular error of the pendulum and controlling the arc of vibration, one end of a short helical spring is attached to the pendulum rod, the other end of the spring being fixed on the centre line below the pendulum suspension.

[edit] Memories

Do you remember stories about clocks? Add your memories.

[edit] In the Science Museum's Records

Inv. No: 1922-675