This amplifier for electrometer can work with currents of 0.1 pA in a band of 1 Hz. The circuit is from NASA in a publication of the 60s. Transistors are general purpose types.
This circuit shows how to add a 1st regulator to a source that already has a step for this...
This effects circuit was found in a 1995 documentation. The circuit causes a sequence of LEDs to...
Found in an Electronics World of 1968 this circuit can use any SCR and diodes depending on the...