"C" BATTERY MODIFICATION FOR SPECTROPHOTOMETER 



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"C" BATTERY UNIT 



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SCREEN VOLTAGE AOJ 

 (CENTRALAB PA 2001) 



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TEST SELECTOR SWITCH 

 (CENTRALAB PA 2005) 



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PUSHBUTTON SWITCH 



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POLARITY SWITCH 



I METER TEST KIT | 



Figure 4.--Diagram of wiring in "C" banery unit and meter test unit. (Terminal strip positions B and C are connected to 

 the yellow and white leads in the Beckman DU Spectrophotometer, respectively.) 



meter which shows the rate of charge 

 of the batteries. In addition, the oper- 

 ator may select from this unit the bat- 

 tery which will be used during the 

 operation of the instrument. 



The "A" batteries are contained 

 in a separate box and may be placed 

 in some convenient or rem.ote location. 

 Connection between the storage battery 

 box and charger unit is made by a six- 

 conductor "extension" cord equipped 

 with polarized amphenol or similar 

 connectors. These connectors (also 

 used elsewhere in the modified in- 

 strument) have given excellent service 

 and have shown no tendency to corrode 

 under these conditions. 



Figure 5 shows the wiring diagram 

 for the battery charger unit. 



Due to a vessel's motion the level 

 of the electrolyte in the "A" batteries 

 (i.e., 6-volt storage batteries) must 

 be kept at a high level or an unstable 

 dark current will result. Mounting 

 these batteries athwartships also helps 

 stabilize the dark current for the same 

 reason. Also, best results have been 

 obtained by soldering the 6-volt, 2- 

 volt, and negative leads directly to the 

 battery. 



Modification of Cell Holder 



One spectrophotometer is used 

 solely for the measurement of phyto- 

 plankton pigments. In tropical waters 

 this requires the use of a 10-cm. path 

 length and an absorption cell of rela- 

 tively small volume (i.e., ca. 5-6 ml.) 



