Joule Thief: Tutorial: Basic JT Made From Recycled TV Parts
By request, a TKTutorial on making a simple Basic Joule Thief from parts scavenged from a discarded TV and a yard light and/or a CFL base. I only found a couple of transistor types in the TV that would -not- work in the basic JT circuit I’ve shown here. It seems that most any low-voltage NPN will work and even many high voltage ones like the 2sc1514. By varying the turns ratio in whatever transformer you use, you can get higher voltages, more efficiency, and even start blowing out LEDs from the sheer power. Different transistors will be more or less efficient. Try a diode in place of the base resistor. Experiment! Whenever you have two coils interacting, as here, always try all combinations of hookups before you give up. Many times the phasing (polarity) of the coils is important for the effect you are trying for. In the JT case, just reverse ONE of the coil polarities at a time. There are 4 possible combinations, two should work and two won’t, and of the two that do work one may be slightly better. If you use coils of different turns ratios, then you have more possible combinations because you can have the lesser number turns coil in either position, as well as phasing both ways. Experiment! With a single AA or AAA battery you aren’t going to blow any transistors, but if you get the right turns ratio you might blow some LEDs! Then you know you are on the right track. NPN transistors tested and known to work in this circuit as shown: EBC: 2n2222, 2n2369, 2n3904, 2n3053 …