This commercial transistor tester circuit (EICO 666) is from a Japanese publication from the 1960s. The switch selects the types of test with the switching of the terminals and the gain ranges.
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...