Found in an old Radio Electronics, this circuit applies to frequency meters for frequencies up to 100 MHz. The input impedance is in the order of 1 M ohm.
This circuit was found in a 1967 American documentation. The switching diode (tunnel) used is an...
This circuit was found in a 1975 documentation. Operational amplifiers must have a symmetrical source and...
The diagram shown was found in a 1975 active filter manual. The tuned frequency range depends on...