Joule thief are small, fun circuits which exploit a few characteristics of electronics and LEDs in order to “steal” virtually all of the energy stored in a battery. They can operate at … ...

A common project among electronics tinkerers is the joule thief, a self-oscillating circuit that can “steal” the remaining energy in a battery after the voltage has dropped so low that most ...

4. The plot depicts the Joule Thief waveforms with collector voltage (yellow) and base voltage (blue). Transistor Q5 also is used to sense the presence of PV voltage through D4 and R15.

The Joule-Thief Energy Harvesting demonstration kit includes a RLP Smart Energy Beam along with collection and storage electronics in a matchbox-size package. Price is $699.

If you choose a green or red LED instead of blue, the “joule-thief” circuit can be eliminated, and the LED connected between the upper terminal of R5 and “+A”. Due to the wide supply voltage range, ...