gets a 2.7V LED running off a half-drained AAA cell. In EC simulation the output cycles at 645Hz, but in reality it's actually 26.3kHz. transformer is a 4.8mH line isolator from an old network card.
the high frequency is created from the 10nF cap on the bias resistor decoupling the transformer and holding the transistor base steady. the LED makes the same amount of light, but the higher frequency makes the circuit much more efficient. at 1V, the average drain on the supply is 12mA
