Found in Popular Electronics from the 90s, this circuit generates signals in a frequency range set to R7 and basically determined by C1. Operational and equivalent transistors can be used.
Suggested by Philips documentation from 1968, this circuit uses components from the era that can...
This circuit uses NO sensors and was found in an American publication in the 90s. The supply must...
Found in American documentation from the 1990s, this circuit generates signals in the 350 to 500...