Found in American documentation from 1968, this circuit has an acute cut-off of the frequency to which it is tuned and which depends on RC. Transistors may be modern equivalents of general use.
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...