We found this time base of 0.1 to 90 seconds in a circuit manual from the 90s. The single-use transistors used are common and the frequencies given by the adjustment by the potentiometer.
This circuit includes a battery charging system and an inverter for operating a fluorescent lamp....
This is one of the many versions of cricket that the reader can find on this site. This circuit is...
This circuit emits a sound when a magnetic field, of a magnet, for example, approaches the sensor....