This circuit was found in a 1965 Radio Shack documentation. The transistors are from that time. The circuit can be implemented with current transistors and lower voltage supply.
This circuit is from Signetics' 80s documentation. The circuit generates 100 kHz signals according...
This circuit was found in a Motorola documentation from the 90s. The transistor used is uncommon...
This two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The...