Explanation of the Explanation of the Reed switch motor Reed switch motor

RSM with transistorRSM with transistor

January 2012

Reed switch motor in action Reed switch motor in action

Since the main switch is open, there is no current in the circuit.

Since the main switch is open, there is no current in the circuit.

00BE

C

Since the base is supplied, the transistor allows a strong current between the collector (C) and the emitter (E). This strong current supplies the electromagnet and creates a force of repulsion between its south pole and the south pole of the permanent magnet close by. The motor begins to turn clockwise.

Since the base is supplied, the transistor allows a strong current between the collector (C) and the emitter (E). This strong current supplies the electromagnet and creates a force of repulsion between its south pole and the south pole of the permanent magnet close by. The motor begins to turn clockwise.

The main switch is now closed. Since the magnetic switch is close to a magnet, it too, is closed. Weak current therefore runs through the right hand loop and supplies the base (B) of the transistor.

The main switch is now closed. Since the magnetic switch is close to a magnet, it too, is closed. Weak current therefore runs through the right hand loop and supplies the base (B) of the transistor.

11

SN

E B

C

The main switch is still closed. Since the magnetic switch is far enough from a magnet, it opens. Current in the right hand loop is interrupted. Since the base is no longer supplied, the transistor stops conducting.

The main switch is still closed. Since the magnetic switch is far enough from a magnet, it opens. Current in the right hand loop is interrupted. Since the base is no longer supplied, the transistor stops conducting.

The current in the left-hand loop therefore becomes nil. The magnetic field created by the electromagnet disappears. The motor turns solely due to the inertia of the rotor.

The current in the left-hand loop therefore becomes nil. The magnetic field created by the electromagnet disappears. The motor turns solely due to the inertia of the rotor.

22B

C

E

The electromagnet is not supplied. Because the core of the electromagnet is ferromagnetic, however, a weak force of attraction appears between it and the approaching magnet. This weak force helps the rotor in its path.

The electromagnet is not supplied. Because the core of the electromagnet is ferromagnetic, however, a weak force of attraction appears between it and the approaching magnet. This weak force helps the rotor in its path.

The main switch is still closed. A magnet is approaching the magnetic switch. The magnet is not close enough yet, so the magnetic switch remains open.

The main switch is still closed. A magnet is approaching the magnetic switch. The magnet is not close enough yet, so the magnetic switch remains open.

B

C

E

33

And the same cycle begins again, four times for each full rotation of the rotor.And the same cycle begins again, four times for each full rotation of the rotor.

44B

C

E

SN

11

SN

E B

C

22B

C

E

B

C

E

33

44B

C

E

SN