directly or the calibration curves given in Fig. 5 may be used to determine the intensity. In order to alternate the capacitors in the charge and read positions, the positive pulses from the Schmitt trigger are also fed into integrating circuit, C-30 and R-32. The voltage developed across the integrating circuit causes the cathode potential of a cathode follower, V-4A, to rise, thus triggering the second Schmitt trigger, vV-6. To prevent spurious pulses from actuating, V-6, R-32 is adjusted so that the integrating circuit will accept 5 pulses before the potential rises high enough to fire the Schmitt. When the second Schmitt (V-6) is triggered, a negative pulse is produced at the plate of V-64 (Fig. 19��) which is applied to the third Schmitt trigger (V-1C), and a positive pulse at the plate of V-6B (Fig. 19d) which is applied to a binary stage (V-9), the polarity of the pulses is such that these circuits are not affected. However, when the train of pulses stops, the cathode potential of V-4A drops the Schmitt trigger returns to its normal state producing a positive pulse on the plate of V-6A and a negative pulse on V-6B. The negative pulse from V-6B triggers the binary stage (V-9). The relay K-2 in the plate circuit of V-9A is actuated or released, depending upon thie previous condition. of the binary, reversing the position of the step charger capacitors. are shown in Figures 19e and 19f. The plate voltage variations The positive pulse from V-6A fires the third Schmitt trigger (V-1C0), Figure 19g, actuating a relay (K-1) which discharges the capacitor just switched from the read to charge position, thus preparing it for charging by the next train of pulses. - 43 -