Piezoelectric Buffer (CB21152E)

This circuit was found in American documentation from the 90s. It serves as an amplifier for a piezoelectric transducer.

LM3914 with Overscale Alarm (CB25112E)
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
TTL Siren (CB18966E)
This circuit can act as a shield being controlled by a microcontroller by pin 1 or 2. The...
Crystal Controlled Signal Source (CB6147E)
This circuit was obtained from a 1980's QST magazine. The circuit can generate 1 to 15 MHz signals...