In this circuit of an American documentation of the 90s, when the light is cut, we have the production of a pulsating tone. R3 determines the trigger sensitivity.
This is the circuit of a “follow the line” type robot with inductive sensors published in Radio...
With a unijunction transistor and a tunnel diode it is possible to obtain rise times of 1 ns with...
This receiver for listening to headphones and 2-battery power was found in Japanese documentation from the...