This wide-range radiation monitor was found in a 1980s documentation. The circuit uses a diode as a sensor and is quite critical requiring shielding shown in dashes to prevent snoring due to gain.
This three-transistor amplifier uses a JFET at the input to increase the input impedance. The...
We found this simple mixer in a 90s Radio Electronics. The used FETs are still common. The inputs...
This circuit was published in an Italian magazine Radio Elettronica in February 1976. The...