This circuit uses a current regulator from the 90's. This component is uncommon nowadays. The transistor admits equivalent.
With this circuit it is possible to add a conductance scale to a common multimeter. The circuit was...
With a touch of S1 this circuit keeps a small strand of nichrome warm enough to light a cigarette....
Mouser Electronics has in stock the MUSBR robust connectors for USB 30 applications from Amphenol. These...