This sensitive circuit was found in the August 1971 issue of Radio Electronics magazine. The SCR is equivalent, and the transistor may be a BC548. The load may be a relay.
We found this bench circuit in a Radio Electronics magazine from July 1962. The transistors are...
This circuit is from an 80's documentation. The circuit makes use of a component of the era, the...
This Linear Technology circuit can measure currents from 100 pA to 100 uA. The circuit is from the...