This circuit is a single transistor flyback (Joule Thief) circuit that features a third coil. With it, flash duration and brightness is much enhanced, without resorting to large value capacitors. This ...

This simple circuit has helped me out on many occasions. It is able to check transistors, in the circuit, down to 40 ohms across the collector-base or base-emitter junctions. It can also check the ...

These days, if you want to flash some LEDs, you’d probably grab a microcontroller. Maybe you’d go a little more old-school, and grab a 555. However, [Jacob] is even more hardcore than that, as ...