This circuit is from 1999 documentation. However, it can still be easily assembled, as all components used are common. The sensors can have their quantity increased, being connected in parallel.
This transistorized “grid dip” oscillator was found at Radio Electronics in June 1953. The...
This circuit has a very traditional configuration that can be found elsewhere on the site. R2 and...
This high input impedance amplifier stage was found in a 1963 documentation. The transistor...