This circuit, suggested by an Electronics World of 1969, keeps a blinking LED for a while when a power outage occurs. Time depends on capacitor C1.
This test consists of a simple Hartley oscillator using a transformer of the type found on older...
n be assembled with BC558 transistors for low power transistors and a BD136 for the output. The...
This oscillator takes advantage of the 2000 ohms headphone inductance as the oscillator circuit coil....