Found in a 1964 Electronic Design this circuit compares two signals by providing the inverse of the algebraic sum of their frequencies. The circuit can be made with modern equivalent transistors.
This circuit was found in Radio Electronics magazine from November 1960. The circuit is powered by a...
In the figure we have an application in which the input and output voltage are equal, with the...
We found this circuit in a Radio Electronics from the 90s. The circuit is for conventional analog...