A Counting Circuit
Author: J.B. Hoag
|Fig. 19 A. A simple counting circuit.|
In Fig. 19 A, the relay in the plate circuit is turned on whenever the grid voltage becomes more positive than the striking potential of the thyratron. When the relay is energized, its contact is broken, the plate voltage is removed from the tube, and the plate current ceases to flow. The moving part or armature of the relay may be used to operate an ordinary mechanical counting device. In the circuit shown, this is accomplished by means of a ratchet wheel, but other mechanisms can be used. There is an upper limit to the rate at which the parts of the relay, ratchet, and mechanical counting device can move. Consequently there is an upper limit to the rate at which a succession of impulses can be applied to the grid of the tube and still be recorded in correct number.