. Electronic apparatus for biological research . Fourth Eccles-Jordan circuit Figure article should be consulted). Scale of ten counters can be connected in chains to form scales of 100, or 1,000 and so on. A cheaper kind of scaler, using Eccles-Jordan circuits but relying on capacitors instead of diodes for coupling, has been discussed by Gottlieb^. It seems to the author that circuits of this kind might be rather more difficult to get going than the diode-coupled variety. Eccles-Jordan design procedure has been considered by Taubio. Scalers of the Eccles-Jordan type are reliable and wi
. Electronic apparatus for biological research . Fourth Eccles-Jordan circuit Figure article should be consulted). Scale of ten counters can be connected in chains to form scales of 100, or 1,000 and so on. A cheaper kind of scaler, using Eccles-Jordan circuits but relying on capacitors instead of diodes for coupling, has been discussed by Gottlieb^. It seems to the author that circuits of this kind might be rather more difficult to get going than the diode-coupled variety. Eccles-Jordan design procedure has been considered by Taubio. Scalers of the Eccles-Jordan type are reliable and widely used, but they contain a large number of valves, and special decade counting tubes have been developed to effect simplification and gain economy here. These have been reviewed by Kandiah^^. Briefly, they fall into two categories: (1) Glow discharge types in which a glow occupies one of ten positions, circularly arranged, in a soft valve. Each input pulse moves the glow on to the next station, and the count is read off" by observing the position of the glow against an external annular numbered escutcheon. At the com- pletion of each complete circuit of the glow the tube delivers a 'carry' pulse which may be used to operate further tubes. (2) Cathode ray types, in which a cathode ray beam in a hard valve is arranged to occupy one of ten stable positions. At each position the electron beam bombards an appropriate numeral, made of fluorescent paint, causing it to glow and enabling the count to be read off. The beam is transferred to the next position by setting up electric fields within the tube with suitable electrodes. Glow discharge decade counter tubes are known variously as Dekatrons or Nomotrons, according to the manufacturer. Cathode ray types include 649
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