Found in a 1967 General Electric documentation, this meter uses Nixie tubes, popular at a time when LED and liquid crystal displays did not yet exist.
This circuit, found in documentation from the 1980s, uses an operational amplifier from that time....
This low frequency sinusoidal oscillator was obtained in documentation from the 1970s. Operational...
This circuit was found in a 1980s documentation. It is intended for remote vibration monitoring...