Two-tone solar buzzer (CB20493E)

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

Low drift voltmeter (CB7910E)
Found in American documentation from the 90s, this circuit uses common FETs. It has a range drift...
Diode Bridge (MSB077E)
This circuit is both simulation of the operation of a diode bridge and a test circuit for this...
Photodiode selective preamplifier (CB7816E)
Found in American documentation, this circuit for modulated infrared signals can be tuned to a...