This receiver was found in an article in Electronics Now magazine in March 1994. The coils are critical, as shown in the figure. Listening is through headphones.
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
With this circuit the visually impaired can easily locate important places inside the house, such...
In the figure we have the way to use the transistors of an old-paired pair as a trigger circuit. The...