Found in an English publication from the 1980s, this circuit can be built with equivalent transistors such as the BC549. The signal must be applied to an external amplifier.
This circuit was found in February 1976, Radio Electronics magazine. The circuit is powered by 12 V...
This circuit was obtained in a 1973 publication, being implemented with TTL technology. The...
Found in a 1969 documentation on neon lamps, it actually takes advantage of the durability of the neon...