Joule Thief Circuit - User Requested: guidebot

This circuit is a self oscillating voltage boosting circuit. It takes low voltage DC source (AA battery for example) at 0.6V - 1.5V and boosts it up to 50V (depending on physical layout) It self limits by the current draw so if you hook up a White LED that need 3.5V then the circuit will boost the battery voltage to 3.5V to run the LED. The duty cycle is very low (~20mA average output)and the frequency can run into the MHz range making it very efficient at getting all the power out of the battery until its last dieing breath.

This circuit is a classic, easy to build out of junk, low part count, simple and very useful letting you make small LED flashlights or power small IC's which normally require multiple Cells off of a single low voltage cell or power source, also useful for boosting solar panel voltage to charge higher voltage batteries.

Joule Thief Circuit, 0.6V minimum supply (may work at 0.45V depending on NPN transistor Base Emitter forward bias voltage drop)  Keep the circuit voltage below 2V as for most LED's this may push to much current through them and cause them to fail.
Here is the physical layout of the circuit to help in winding the ferrite bead or toriod transformer for the circuit.

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