Demonstraton Electric Bell

Description

Wound on rectangular bobbin, for use with 220 – 240 V AC mains with detachable mains connector with moulded plug, A 4 mm socket is provided for earthing.

Description

Generates both AC and DC. When the two brushes of the generator are put in the two ends of the commutator, the output is an AC. When the brushes are put in the middle of the commutator, the output is a DC. Includes Instructions.

Description

Investigate the working principle of circuit breaker type fuse with this demonstration model. The apparatus is built on a robust plastic base and includes resistive loads to simulate external wiring circuits. Applications of the thermal response of bimetal strips and also electromagnetism (movement from a solenoid) are clearly demonstrated in this model. When a 12 V DC supply is connected (not supplied) the LED lights to show that current is flowing in the external circuit and the bi-metal strip can be seen to bend as its heater coil raises the temperature. After a few minutes the bending is sufficient to trip the mechanism and the current path is broken. At any current selection a short circuit situation can be initiated by pressing the red button and this produces an immediate response from the solenoid to disconnect the supply.

Description

The motor consists of a two pole armature mounted between the ends of two bar magnets. The armature has a two section commutator and a pair of slip-rings on its shaft and is so constructed that the wire cannot slip off the iron core. The upper bearing and brushes for the commutator are mounted on a strong upright. Separate brushes are provided for the commutator and for slip rings and each are connected to a terminal. The magnets are held in position by thumb screws.