This is the traditional voltage follower configuration with the 741 operational amplifier. The circuit is from 1976 documentation and the power supply must be symmetrical from 6 to 15 V.
This 1964 Electronic Design circuit uses a photo-FET as a sensor. The component is rare today. |...
This metal detector circuit uses an AM radio as an indicator. The radio is placed off-station and tuned...
This circuit is from a 1976 technical documentation. The FET can be MPF102 or BF245 and the coil...