Found in American documentation from the 90s, this circuit can measure frequencies on a linear scale from 0 to 1 kHz. The components can be changed to measure other ranges.
We find this circuit in documentation from the 1980s. The triac and diac are of conventional types...
Found in a 90s Popular Electronics, this circuit uses general-purpose transistors, serving to...
This control for 1200 W of power was found in the documentation of General Electric of 1966 has a...