Found in a Popular Electronics from the 80's, this circuit makes use of a time integrated to control a relay in a timed way. R2 determines the activation time.
This circuit, bridge type, was found in American documentation from the 60's. The transistor is...
This inverter is critical for transformers and can use modern equivalent transistors like MJ2955 on...
This low-current power supply was obtained in Japanese documentation from 1968. The currents are...