This circuit that generates signals between 1.5 and 2 kHz was found in a documentation from the 90's. The capacitor C1 can be changed to obtain other frequencies.
This low frequency oscillator with an operational amplifier of type 741 has adjustment of the mark...
This circuit was found in a Popular Electronics from the 90s. Transistors are general purpose...
The AT21CS11 memory device offers an extended voltage range to accommodate lithium-ion battery...