This 1967 Electronics World circuit is suitable for frequencies up to 1 MHz. The setting applies to virtually any junction FET.
This circuit works only with carbon microphones, due its low impedance. The speaker should be good or...
This preamplifier is intended for the use with magnetic pick-ups. Power supply must have voltages...
We found this amplifier in a publication of 1990, but it can be mounted today with some exchanged...