This TTL circuit was found in a 1978 technical documentation. The power must be supplied with 5 V. It converts ASCII characters to hexadecimal.
A touch in this circuit turns-on the lamp or the relay. Power supply is according the lamp or...
This an old commercial receiver found in a year 1958 magazine. The circuit uses some transformer...
We found this very simple cable fitting circuit in an Electronics Now from the 90s. ...