The transformer is a device which is the core made of sheets of electrotechnical steel on which the isolated wire is reeled up. Undervoltage is carried out at the expense of a ratio of quantity of rounds of primary and secondary windings.
Instruction
1. Calculate characteristics and quantity of rounds of future lowering transformer. For this purpose learn tension in primary network, tension which you want to receive at the exit, and core cross-sectional area. So, if you plan from tension in 220 B to receive 12 B at cross-sectional area in 6 sq. cm, then it is necessary a constant for average transformer iron which equals 60, to divide into the square. Receive that 10 rounds are the share of each Volt. Increase it by 220, and the result is and there is a quantity of rounds of primary winding. The secondary winding pays off also: Increase 10 rounds by 12 Volts.
2. Take a wire which has a silk or paper isolation. Choose section small, about 0.3 mm. For a secondary winding find wires with a section of 1 mm. Stock up with tin for production of the core. For this purpose take cans and cut out from them about 80 strips 2 cm wide and 27-30 cm long. Anneal them in the furnace and let's cool down then clean off scale, varnish them and paste over on the one hand with thin paper.
3. Make a framework for the coil. It can be made of thick cardboard. Previously reel up on it several layers of proparafinenny paper. Then start winding of a wire. You watch that after two-three rows paper was laid. Fix the ends of primary winding on a framework and lay some more rows of proparafinenny paper.
4. Lay a secondary winding in the same direction, as primary. Do not forget about conclusions which need to be made from 120 and 240 rounds (by calculation). Insert iron strips into the ready coil which have to enter half the length. Round them a framework on the one hand and connect below. Leave an air gap between the core and a framework.
5. Make the basis for the transformer. For this purpose take a small board about 5 cm thick, you fix by means of metal brackets which bend around the lower part of the core. Bring the ends of windings to a framework and fix them to contacts.