This circuit was found in a 80s American documentation. The zener diodes determine the points of action of each stage and the transistors can be general purpose types.
An OR gate can be implemented with an LM3900 transconductance operational amplifier. The circuit is...
This traditional relay configuration, found in old documentation, is intended for 2A relays for...
This simple radio circuit was obtained in a Japanese publication in 1967. The circuit uses...