The switch is then connected to the other input on the bridge rectifier where on its output, the positive wire was directly connected and the negative wire was connected through a piece of a metal strip that acted as a current shunt.
One of the wires goes directly to what seems to be the bridge rectifier and the other two are soldered to the voltage select switch that was mounted on the top. The transformer is wired directly to the mains input on the primary side of the windings and the secondary winding has a middle tap for the 6V output so the secondary winding has three wires coming out of it. To learn how the charger worked, and how it was built, I used my multimeter to trace out all of the connections, and also I did some voltage measurements in different parts of the circuit.
