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.
Found in an Electronic Design from the 80s, this circuit generates a 500 Hz signal and can be used...
This circuit, which can generate voltages up to 25 V, was found in the December 1992 issue of...
Found in a 1980s publication for amateur radio, this circuit employs an MC1596G which is a...