Sets vary in size but usually consist of wooden blocks, yokes, rivets, magnets, wire, axels and bands. When constructed, they should be connected to a low voltage supply or batteries according to manufacturer?s guidelines.

The kits can be notoriously fiddly to set up and so require a bit of preparation beforehand. It is advisable to set one up perfectly for the teacher to use as a demonstration model and for the pupils to use as a guide. A bit of trial and error is usually enough to get these motors running. Full instructions are usually supplied with these kits. These could be copied and added to the kit or made into worksheets to accompany the lesson.

Newer ?Hodson? motor kits are now available through suppliers which work in exactly the same way, the only difference being appearance and that these kits use moulded plastic barrels.

Pieces will ultimately get broken and go walkabout so keeping them in a segmented tray and counting pieces in and out will increase the life of parts. Some lab suppliers stock an array of spares.

Tips:

• Make sure the slab or ceramic magnets are the correct way round. Put two together so they stick and then separate without turning them. Stick one each side of the yoke.
• Use solid core insulated wire to ensure good contact between the brushes and commutator.
• Don?t connect to the supply for too long as this may melt the plastic coating on the wire.
• Keep the wrapped wire neat and taut. This will ensure the barrel is balanced as it turns.