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, which can function as a small transmitter, was found in the July 1978 issue of Radio...
This circuit was found in a Spanish magazine that no more existis, Mundo Electrónico, in a...
Using a transconductance operational amplifier, this circuit was found in July 1983 Radio...