This circuit from Ferranti was released in 1969. It makes use of the company's transistors that admit current equivalents. The input voltage is 30 mV for total deflection. The band pass is 800 kHz.
This circuit was found in American documentation from the 90's. The circuit applies to any...
We found this circuit in an English publication from 1980, but it can be assembled with BC548...
This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when...