An SCR topology transmogrifies into BJT two-wire precision current source with a self-resetting fault-current limiter.

A frequently encountered category of analog system component is the precision current source. Many good designs are available, but concise and simple arithmetic for choosing the component values ...

At first glance, [RobBest]’s constant current source looks old school. The box is somewhat old-fashioned, featuring switches and binding posts. Most importantly, there’s a large analog meter ...