Two-tone solar buzzer (CB20493E)

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

Low Drift Sampling and Hold (CB5954E)
This low drift or offset circuit is from an 80's documentation. The configuration can be made with...
VHF to AM Converter (CB17047E)
This circuit makes it possible to receive VHF stations on an AM receiver. The output is connected to...
Sampling and Holding (CB15888E)
The figure circuit retains in the capacitor load, the value of the input voltage, keeping it...