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.
In the figure we have the way to connect two high power operational amplifiers LM12 to double the...
This circuit uses the Linear Technology LT6505 and was found in a 2005 manual. The circuit is for 24 V...
a This circuit was obtained from a 1978 Practical Wireless. It causes a low-power 1.5V lamp to...