The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x 50 mA relay. The other components are common.
The circuit shown in the figure uses a programmable unijunction transistor (PUT) of the BRY39 type...
This circuit generates a 5V rectangular signal. The circuit is suitable for calibrating TTL...
This configuration, explored in other applications of this section and website, was found in a 90s...