This low frequency oscillator circuit was found in an Electronic Design from the 90s. The transistors are common types, and the frequency is given by the crystal.
8E) This siren was found in a 1989 documentation. It uses only transistors and includes two power...
We found this circuit, which appears with variations on this site, in a European documentation from the...
The operational amplifier used in this configuration is of an uncommon type today. The circuit can be...