The difference between this circuit and the previous one is that it uses PNP transistors. The circuit is from Radio Electronics magazine from July 1968. The frequency depends on R1 and C1.
This circuit is a high voltage source for a gas LASER. We found it in a documentation from the...
This intercom with wires up to 30 meters separation between the stations is from the Linear...
This circuit is from an old American publication from 1977. Transistor Q1 can be a TIP42 and Q2 a...