Steel wire – pancake coil-Joule Thief.ASF
This is a low amp draw “Joule Thief” LED circuit that uses a bifilar steel wire pancake coil instead of the usual ferrite toroid design. The wire is telephone line that is made with steel instead of copper wire. Two of the four wires in the line were used for the circuit. I show the circuit here running off one of my soda can cement batteries that was made over four months ago. The loaded voltage is only about 1/2 volt with the amp draw around 4 micro amps.