Two-tone solar buzzer (CB20493E)

This circuit was found in a 1991 publication. The transistor can be a general-purpose type.

Signal conditioner (CB9453E)
This circuit is intended to recover a very weak signal at a receiver, for example, a CW signal or a...
Sine to Square Converter (CB6592E)
Found in a 1964 Electronic Design this circuit makes use of components of the era. The output is 2 V...
Hartley for 1 MHz (CB25588E)
This oscillator was found in the July 1993 Electronics Now magazine. The coil is wound with...