Found on an 80's Elektor, this circuit uses common components, being the diode a general purpose germanium. The coils select the frequency range of the indicator that reaches 60 MHz.
This amplifier was found in a 1957 Rayrtheon documentation. The circuit can be fitted with a BC558...
This circuit was obtained from the May 1971 issue of Radio Electronics magazine and is intended for...
Although it is a common configuration today, this circuit was taken from an old publication. The...