A joule thief is a minimalist self-oscillating voltage booster that is small, low-cost, and easy to build, typically used for driving small loads. This circuit is also known by other names such as blocking oscillator, joule ringer, vampire torch.
It can use nearly all of the energy in a single-cell electric battery, even far below the voltage where other circuits consider the battery fully discharged (or “dead”); hence the name, which suggests the notion that the circuit is stealing energy or “joules” from the source – the term is a pun on the age-old expression “jewel thief”.
components needed
- NPN transistor
- 1k resistor
- led
- 1.5volt battery
- enamelled copper wire
- ferrite core
how to make the coil
we need a ferrite core I salvaged this core from an old CFL.make 30 turns with enamelled copper wire on the ferrite core
please watch the video for better experience
how this works
at first very little current flows through the base and collector of the circuit that will create induction in the primary coil and thus increase in base current and this will increase collector current and this cycle repeated until the saturation. at saturation, the transistor will turn off and the stored energy in the secondary coil flows through the led and which is greater than the input voltage because of the secondary coil in series with input source so. there is a boost in voltage
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