This circuit was found in a 90s Electronic Design. The integrated circuits are from that time. Frequency multiplication can be done for odd integers.
In the original version of this 1987 circuit, the loads are lamps, but it can be adapted to drive a...
This circuit was found in an Italian magazine Radiorama from 1960, but it can be assembled with...
This relaxation oscillator with solid-state triggering element was found in an old European...