This circuit accurately monitors a 5 V TTL source. The circuit is from National Semiconductor's Linear Applications Handbook.
September 2015 – It can be found at Mouser Electronics the new drivers of high voltage LEDs HV9805 from...
This simple circuit with two transistors was found in a 1985 publication. The power can come from...
This circuit was obtained from an Electronic Design from 1964. Transistors admit modern...