Electric Bell

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

This apparatus is an effective demonstration of how the earth wire and fuse act together to protect both the user and the appliance. When the appliance is connected correctly and the LEDs in the appliance will illuminate to show the appliance is working. A fault is then demonstrated by swapping the live wire from inside the appliance to the case to show either the fuse melts (protecting the user and appliance) or in the case of no earth wire, the LEDs illuminate to indicate the passage of current through the person to ground. The fuse is easily visible and can be seen to ‘blow’ when a fault occurs.The unit is supplied with 10 m of fuse wire and full instructions. A 12 V DC power supply is required. Connections are made via 4 mm shrouded sockets.

Description

A simple kit for students to gain insight into field poles, armatures and switches, one mounting base, two coils of insulated wire , field pole, mounting bracket, two armature halves, one piece of insulating tubing, motor shaft, two commutator insulators, two bronze wire brushes, two shaft supports, four paper fasteners, a AA battery holder and 6 each of screws and nuts. Requires one AA battery, not supplied, with assembly instructions.