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 low-power audio amplifier was found in the April 1973 issue of Radio Electronics magazine. The...
This interesting multi-channel circuit was found in the August 1988 issue of Radio Electronics magazine....
This circuit includes a battery charging system and an inverter for operating a fluorescent lamp....