This circuit for analog telephones from the 90s was found in documentation from the time. It lights up a remote LED when the extension is in use.
The 4511 is a 7-segment latch driver providing up to 25 mA in each output. The typical application using the...
This circuit is from the 1983 Intersil manual. The display is a 4.5-digit LCD, and the power...
Found in a Popular Electronics from the 90s, this circuit can act as a transmitter for an audio...