Found in a 1968 Mullard manual, this circuit measures temperature by infrared radiation. The sensor is of the type that is difficult to obtain today.
This circuit keeps the neon lamp on for a moment when it receives a pulse. The turn on time...
This circuit was found in General Electric's 1965 documentation. It appears elsewhere on the site....
This configuration was found in a 1990s documentation. Modern operational amplifiers can be used...