DOUBLE Joule thief

268

03:53:54

Self ossilating circuit that has been the simplest of all and unfortunately difficult to understand for beginners

published 8 years ago

gasboss775

8 years ago

This is actually a very old circuit from the days of valves ( vaccum tubes ) called a blocking oscillator. The output from the transistor is fed back to its base via the transformer, the transistor then switches to the opposite state ( either on or off ) which is fed back to the base. The same process causes the transistor to flip back the way. The switching of the transformer current generates back emf, that in turn lights the LED. The inductance of the transformer determines the self oscillation frequency.

BillyT

8 years ago

With the addition of a couple of extra components, ie; a blocking diode and a storage capacitor and by using a low current red led (1.7V @ 2mA), some extra tuning will enable the led to be on more consistently. http://everycircuit.com/circuit/5489344255361024

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