This circuit can function as an output shield for microcontrollers, being compatible with TTL logic. The frequency is adjusted in the trimpot. TTL power is 5 V.
This circuit was discovered in an English publication in 1979. The circuit can still be assembled with...
This circuit whose transistors depend on the lamp current was found in Radio Electronics magazine from...
This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine....