Found in documentation from the 1980s, this circuit can have several adaptations to use modern transistors and LEDs instead of the lamp. The power supply voltage can also be changed.
This circuit was found in a 1974 publication. It consists of a voltmeter for high voltages, up to...
This shield circuit uses a common CMOS port. The voltage depends on the interfaced logic. The...
This circuit is from American documentation from the 70s. The circuit makes use of the operating system...