This circuit for very low frequencies was found in an American documentation from the 90's. Transistors are for general use and the frequency depends on C1 and C2.
The L293 circuit is not common today. We found this circuit in the 1982 SGS linear integrated...
We found this bridge circuit in Electronics Now magazine from September 1995. The instrument can...
We found this divider in a circuit manual from the 90s. The circuit is intended for operation with...