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 amplifier was found in a 70s documentation. The product gain x bandwidth is 350 MHz. The...
This circuit mimics the trill of a bird. We found it in an American documentation from the 90s. It is...
With the values indicated for this circuit, the lamp will flash 60 times per minute (1 per...