Bench thermometer (CB20501E)

With an ultra-low consumption, this circuit can be powered by solar cells. The circuit is from a 1991 documentation.

Four Transistor Reflex Receiver (CB961E)
This an old commercial receiver found in a year 1958 magazine. The circuit uses some transformer...
Laser Diode Modulator (CB4850E)
This circuit allows modulating a laser diode with low frequency signals. The integrated circuit...
Capacitor Tester (CB4443E)
This simple capacitor tester can be used for electrolytes from 1 uF. In one position of S1 the...