This circuit is from a publication from the 70s. The operational amplifier is from the period. Modern equivalents according to the motor current must be used.
This circuit was obtained from a 1962 magazine. It can still be mounted to be powered from 6 V...
This electronic level or plumb indicator has two mercury switches as sensors. The indication is...
This inverting amplifier has a transistor output stage that can increase its current capacity. Higher...