763 
Sys 
The switches are arranged to give delays up to 360° although addition 
of more Type 2050 thyratrons in the train could extend this. The brighten- 
ing duration for any delay sotting is 360° for the FIRE position of the 
master switch, while the Q CAL position gives brightening for the first 
180° after the selected delay, and the V CAL position gives brightcning for 
the second 180°. In this way, the Q CAL step will be convenicntly located 
on the first half of the record film and the V CAL stcp on the second half, 
The pulse to trip the stepper* for Q- and Vestcp calibrations is taken 
from the brightening output of the first group, 
Manual brightening is produced by applying a step pulse through a micro- 
switch on a cable to one of the inverter grids, The duration of the bright- 
ening is controlled by the time the switch is held closed. 
The Type 2050 thyratrons must be rcsct after cach operation by opening 
the Bt lead through the RESET microswitch which is connected by cable for 
convenicnee. Ignition of the RESET neon bulb indicates that the 2050!s are 
resct. 
The firing circuit utilizes a Sylvania type SNh Strobotron which, when 
tricgered, discharges 1604 f at 250 v through the firing line and charce. 
A transformer in scrics with the firing line produces a pulse at the time 
of firing for initiating the sequence brightening action. 
The SN is triggered by a 2050 thyratron whose firing is controlled by 
the shot switch and firing cam. Normally the two grids are biascd below 
firing potential; closing the shot switch comccts the second grid to the 
cathode, so.that the next time the firing cam shorts the first grict to the 
cathode, the tube will fire, The plate lead of the 2050 is run through the 
naster switch so that the tube can fire only in FIRE position. 
The firing circuit is completely insulated from the other equipment; 
experience has shown that serious pickup and ground loops can arise if this 
is not observed. 
- sw  ———— —S—— ee 
ra : ie 
Sce Section 7(c,iii).. 
