This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
Published in 1988 in Hands On Electronics, this circuit converts the 12 V of a battery into 120 V AC...
The current accross the LED as function of the resistor value is given by the formulas. The...
This circuit was found in an old 1980s valve documentation. The circuit can directly replace a...