This circuit was found in an American publication in 1966. The circuit uses a general-purpose FET that admits an equivalent. The instrument is a 250 uA full-scale microammeter.
Found in an English Maplin magazine in 1983, this circuit has an RIAA equalization. We suggest its...
This circuit was found in a 1979 magazine. We can use any JFET like MPF102 or BF245. The relay is 12 V...
This beat frequency oscillator or BFO was found in an American 1980s documentation. The circuit is...