Solar flashlight (CB20488E)

This circuit charges a battery to power a flashlight at night. The circuit is from an English publication from 1991.

Phase Inverter (CB18959E)
This phase inverter with transistors, used in audio amplifiers, was found in a French publication from...
Colpitts Oscillator (MSB047E)
L1 and C1 determine the frequency of this Colpitts Oscillator. Refer to our section Mathematics...
Tunnel Diode Oscillator (CB22576E)
Shown in Radio Electronics June 1953, this circuit needs a small adjustable source of 0 to 3 V and...