This circuit was obtained in documentation from the 1980s. The triac and the unijunction support modern equivalents. The trigger transformer is 1: 1 turn ratio.
This Rytron transmitter was published in a 1953 book. The circuit can be implemented with a BC558...
Foto-Darlington for applications such as light sensor. In normal applications only the collector and...
This circuit was found in a 90s Popular Electronics. It generates tones given by the oscillators and...