228 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



electrodes was alternated with each successive 

 pulse and a sequence of pulses, moving from left to 

 right looking downstream, was established. Table 

 2 shows this pulsing sequence. 



\^nien the first pulse was delivered, the elec- 

 trodes connected to pulse supply-cable 1 became 

 positive and the electrodes connected to pulse 

 supply-cable 6 (row E) became negative. On the 

 second pulse, the electrodes connected to pulse 

 supply-cable 2 became negative and the electrodes 

 in row E became positive. This sequence of pulses 

 and alternating polarity continued through pulse 

 supply-cables 3, 4, and 5 to complete the cycle. 

 Then, on the first pulse of the second cycle, the 

 electrodes connected to pulse supply-cable 1 be- 

 came negative and the electrodes in row E became 

 positive. On the second pulse of the second cj'cle 

 the electrodes connected to pulse supply-cable 2 

 became positive and the electrodes in row E 

 became negative. Again, this succession of pulses 

 and alternating polarity continued through pulse 

 supply-cables 3, 4, and 5 to complete the second 

 cycle. In the third cycle, the electrodes were 

 energized and the polarity alternated as they were 

 during the first cycle. This process was an auto- 

 matic function of the sequential switching equip- 

 ment. 



Table 2. — Pulsing sequence and polarity changes when the 

 electrodes were wired according to wiring pattern I and 

 energized with square-wave pulses 



Because of technical limitations of the existing 

 sequential switching equipment, polarity of the 

 electrodes was not alternated when the array was 

 wii-ed according to wiring pattern I and energized 

 with half sine-wave pulses. The sequence for 

 this switching operation is shown in table 3. 



The first pulse from the switching equipment 

 energized onl}^ the electrodes connected to pulse 

 supply-cable 1, making them positive, and the 

 electrodes in row E, making them negative. The 

 second pulse energized the electrodes connected to 



pulse supply-cable 2, making them positive and 

 again the electrodes in row E became negative. 

 This sequence continued through pulse supply- 

 cables 3, 4, and 5, until five successive pulses had 

 been delivered. The electrodes in row E were of 

 negative polarity with each pulse. Wlien the 

 fifth pulse had been delivered, the cycle was com- 

 pleted and the sequence was automatically 

 repeated. 



When the array was wu'ed according to wiring 

 pattern II, the pulsing sequence and polarity 

 changes were the same for both the square-wave 

 and the half sine-wave pulses. Table 4 illustrates 

 the pulsing sequence for wu-ing pattern II. 



The fu'st pulse energized rows D and E, making 

 row D positive and row E negative. On the 

 second pulse, row D became negative and row C 

 positive. On the third pulse, row C was negative 

 and row B positive. On the fourth pulse, rowB 

 became negative and row A positive; and on the 

 fifth pulse, row A became negative and row E 

 positive. When this sequence was completed, the 

 cycle was automatically repeated. 



Voltage gradients. — The electrical fields created 

 by the two wiring patterns were determined by 

 analog gradient plotting and are shown in figures 

 11 and 12. The plotting interval is 10 percent of 



Table 3. — Pulsing sequence when electrodes were wired ac- 

 cording to wiring pattern I and energized with half sine- 

 wave pulses 



[Polarity not alternated with this conflguration] 



Table 4. — Pulsing sequence and polarity changes when 

 electrodes were wired according to wiring pattern II and 

 energized with either square-wave or half sine-wave pulses 



