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 allows you to modify the resolution of a measurement bridge. It was found in the...
The four gates of a 40111 IC are used in thes two-out circuit. The output chages their state in a...
This circuit measures the strength of audio signals. We found it in an American publication from...