This circuit was found in Delco documentation from 1965. The transistor is of the time, but any current power PNP with at least 500 mA collector current and 100 V collector voltage can be used.
We find the original version of this circuit in an English publication (1986). It is a...
In the original publication of the 90s a 556 consisting of a double 555 is suggested. The circuit...
Found in an old Raytheon transistor manual, this 4-scale voltmeter has an accuracy that depends on the...