This step of two transistors has a high input impedance due to the use of FET. We can use BF245 for this function and the bipolar can be BC548. The circuit is from an 1975 American documentation.
This circuit was found in the March 1979 issue of Radio Electronics magazine. Integrated circuits must...
This is the transmitter for a remote-control system published in the August 1986 issue of Radio...
The current drained by this circuit, from a 1976 documentation, is 3 mA and the cut-off frequency is...