Figure 3. — Camera master control box. 



Film Takeup Drive 



The JLB-4A and 6230-B magazine provide 

 their own film takeup drive. However, an 

 external drive motor is necessary when the 

 132-BM magazine is used (figs. 4 and 7). Any 

 24-volt d.c. or 110-volt a.c. electrical motor 

 with a clockwise rotation may be used. The 

 pulley on the takeup motor shaft is coupled 

 to the magazine takeup pulley by means of a 

 spring belt from a motion picture projector. 

 A 120-r.p.m. takeup motor is necessary for 

 proper film tension. The film takeup core 

 and film act as a pulley of increasing diameter . 

 When the camera is first started, the diameter 

 of the almost bare takeup core is roughly 

 2 inches. The core-film diameter at the end 

 of a 400-foot run is approximately 65 inches. 

 The speed at which the camera feeds exposed 

 film into the magazine takeup chamber re- 

 mains constant at any given frame rate. The 

 rotation speed of the takeup core will gradually 

 decrease as film is accumulated. The 120- 

 r.p.m. motor will rotate the takeup core fast 

 enough at the beginning of a film roll to keep 

 proper tension on the exposed film. As the 

 core-film diameter increases, slippage of the 

 spring belt compensates for the decrease in 

 r .p.m.' s. 



Camera Power Supply 



Two voltages are necessary for the opera- 

 tion of this system. Because of its availability 



Figure 4.— Large cam- 

 era unit attached to 

 rear underwater hous- 

 ing port. The metal 

 covered takeup motor 

 and tapawrapped power 

 supply are located 

 above the camera and 

 in front of the 400-foot 

 film magazine. 



