This circuit can detect static charges or extremely low voltages. The circuit was found in ancient American documentation and makes use of a JFET. A BF245 which is a more modern transistor can be used.
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...