This circuit is from an American publication of the 80's. It makes use of components of the time. However, the circuit is the basis for a modern shield application since the input is TTL.
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...