A Stepping Scale-of-ten Counting Unit
I.A.D. Lewis, J.F. Raffle · Journal of Scientific Instruments · 1950
A scale-of-ten unit, employing two pentode and five diode valves, has been developed along the lines of the Miller integrating circuit. It is primarily designed for connexion to the output of a commercial scale-of-100 unit to provide a scale-of-1000 with meter indication of the number of hundreds. A number of such units, suitably modified, could be used in cascade to provide any desired scaling factor. Counting is achieved by the collection of discrete quantities of charge on a capacitor. A lower limit to the permissible counting rate, of about one count in 20 sec. at the output, is imposed by leakage at the capacitor. The mechanical counter sets an upper limit of 9 counts/sec. at the output; at this rate counting losses in the circuit are negligible.