My Version Of The Standard Joule Thief Circuit

I used the standard or common Joule Thief circuit as shown on the Wikipedia website. Besides using a single AA or AAA (1.2 to 1.5 V) battery, you can also try a small solarcell or homemade battery such as the saltwater, lemon or "earth" batteries. Joule Thiefs can also be used to charge batteries from small voltage sources, it takes a bit more time, but you will have some useful available power in the battery. Before rechargeable batteries came along, I guess these types of circuits were even more appreciated, but probably not as widely known since YouTube was not around yet. Still, these circuits work just as well with rechargeable batteries, and why not make the most out of their stored energy when you have to. The battery used was a rechargeable NiMH type and was 1.2 volts on the meter without any current load attached to the battery. The white LED will not light at that voltage alone.. I also tested hooking one another LED in series and it worked. So the voltage must have been about 6 V at least to do that. Note that straight 6Vdc would probably burn out even a single LED. I then tested one another LED in parallel to the single LED and it worked also. I tried making a coil on a steel washer, and then a steel bolt, but no luck so far using them. Maby more or less turns or it's just not practical without a ferrite core. Needs more tests sometime. I've recently read that a (used/junked) CFL lightbulb might have a ferrite bead in it. Some computer circuit boards have them ...