Found in ancient documentation, this circuit uses a high voltage transistor of the time. Observe the supply voltage of the neon lamp used.
This circuit is from an English publication of 1982. The bipolar transistor can be a BC548 and the...
We found this circuit in an American publication from the 70s. The circuit has only the integrated...
This circuit is from Texas Instruments' own datasheet for this low voltage operational amplifier. The...