This circuit is from a 1976 Motorola CMOS manual. It can be implemented with modern Darlingtons like those in the Texas TIP series. The load current depends only on the Darlington transistor.
This circuit can be used to control loads up to 500 mA from the outputs of microcontrollers such...
This circuit with transistors in parallel was found in a Radio Electronics of August 1952....
This Linear Technology circuit can measure currents from 100 pA to 100 uA. The circuit is from the...