This circuit is from a 1924 book by Gernsback. The receiver uses two tubes and listens to headphones. Power is supplied by battery with the indicated voltages.
This is the traditional configuration for a limit comparator or window comparator, using two...
In the figure we show how to add a 100k ohms potentiometer to implement an oscillator controlled by this...
This circuit uses one of two D-type flip-flops available on an integrated circuit 4013. The...