762 
APPENDIX Ix 
Beam Brightening and Firing Synchronizer 
41 
This unit synchronizes the firing of the charge with the beam brighten— 
ing for three separate groups of Dumont Oscilloscopes. It is uscd in con- 
junction with the rotating-drum camera drive on the schooner RELIANCE and 
enables location of the recorded shock pulse and calibrations at certain 
points on the camcra film relative to the overlapping ends. 
A master switch with the same positions as that in the master control 
panel* selects the operation desired. Thore is also one group delay switch ~ 
for each of the three groups to determine the delay aftcr firing of the re- 
spective group beam brightening pulses in terms of 180° rotations of the 
drive shaft. 
The synchronizer consists of two sections, —- the sequence brightening 
eircuit (Fig. IX-1) controlling the beam brightoning for the three separate 
groups, arid the firing circvit (Fig. I-2) controlling the firing of the 
charge. 
The sequence brightening chassis contains a shaft driven by the rotate 
ing-drum drive, on which four cams rotate. Two of these cams (0° and 180° 
cams in Fig. IX=1) are constructed-to ground a contact to the drive shaft 
over 10° of a revolution and are oriented 180° apart; a third (firing cam 
in Fig. IX-2) closes a contact over 10°; and the fourth insures a good con= 
tinuous ground contact to the drive shaft. For use up to the present the 
0° and firing cams have been aligned. 
The brightening circuit contains a train of Type 2050 thyratrons, in 
which cach, with the cxception of the first, requires the previous one to 
be ignited before it can be tripped. This is obtained by making the positive 
rise on ignition across the cathode resistor of the preceding 2050 decrease 
the bias of the second grid of the 2050 in question, so that subsequent 
grounding of its first grid will trip it. The first 2050 is tripped in Q 
cal or V cal position by grounding its first grid through the shot switch 
(knife switch on panel) or in fire position by a positive pulse from the 
firing circuit. This sets the second 2050 so that it fires the next time 
its first grid is grounded by the 0° cam, The first grids of 2050's in the 
train after the initial 2050 are connected alternately to the 0° and 180° 
cams, so that the 2050's trip in sequence 180° apart as their grids are 
grounded. In this way, step pulscs 180° apart over a range of 0° to 720° 
rotation from the origin may be obtained across the 2 K resistors in the 
2050 cathodes. 
The group delay switches, one for cach group of oscilloscopes controlled, 
select two step pulses of desired delay and scparation. These are applicd 
to opposite grids cf a cathode inverter stage, producing on one plate a 
beam brightcning pulse of the seiected delay and duration cqual to the sepa- 
ration of the original pulse. 
*Seo Scetion 7(ci). 
= seb 
