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 circuit uses an unusual electromechanical component: a mechanical blade resonator. The...
This circuit from a Japanese publication in 1968 uses germanium transistors from the time like the...
Found in a 90s Electronic Design, this circuit can provide a relatively high-power output. The basic...