You will need:
- Mains transformers, 230V to 12V 2A, 2. The ones used at present by a school may do but it is essential that they are double wound and preferably split-bobbin, e.g. RS Components 207-251
- 4 mm sockets, preferably yellow, 4
- Plastic boxes, with transparent lids, to take the transformer etc, 2
- Terminal block, standard screw terminal, 5A, e.g. RS Components 425-099
- Eureka (constantan) wire, 28 SWG, 3m
- Clear sleeving, 1.6 mm bore, e.g. RS Components 399-899, 3 m
- Wooden rod which will fit into a boss head on a stand, 40 cm
- Connecting wire
a Drill the boxes, each to take two 4 mm sockets. Make holes to mount the transformers and the terminal strips.
b Solder connecting wires to both the high voltage and low voltage sides of the transformer.
c Mount the transformers in the boxes; also part of the terminal block in each box. See diagram.
d Connect the wires as shown.
e Cut two lengths of wooden rod. Make slots to take the sleeved resistance wire.
f Cut 1.5 metre lengths of the resistance wire and two lengths of the transparent sleeving about 1 cm shorter. These may be kept attached to a strip of wood with elastic bands, or coiled.
g If it is considered essential to show the high voltage, holes may be drilled through the lid of the box to let multimeter probes contact the terminal block connections.