Adjustable reference (CB21539E)

This circuit was obtained from an old American publication. The uA702 is a differential amplifier and the diode is a zener.

Gravitational sensor (CB26124E)
Using a capacitor as a sensor, this circuit was found in the 1989 Radio Electronics Experimenter magazine....
Up to 10 hours timer (CB20360E)
Using bipolar, FETs and unijunction this long-lasting timer can reach 10 hours with good quality...
1 kW power meter (CB5448E)
This circuit is found in an American documentation from the 80's. The circuit measures the power of...