This circuit was found in the September 1971 Radio Electronics magazine. The buzzer can be replaced by a relay according to the supply voltage. R1 adjusts the sensitivity.
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...