How many electrodes for a SRG

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Paul Arrowsmith by way of Terry Fritz <twftesla-at-qwest-dot-net>" <p_t_arrowsmith-at-hotmail-dot-com>

Hi fellow coilers, I have decided to build a SRG and are unsure on how many 
electrodes to use to get best results, I assume the capacitor size will have 
some bearing on the choice of BPS.
These are my thoughts on the number of flying electrodes to use on a sync 
rotary gap without conductive ring on disk (using 50Hz supply and 3,000 RPM 
sync motor).

2 electrodes will give 100bps (100%, 100% per cycle).

4 electrodes will still give 100bps if phased to fire at the peak of the 
sine wave as 2 electrodes will line up at 0V crossover and do nothing. But 4 
electrodes can give 200bps if phased to fire at 45 Deg from 0V (Sin of 45 
Deg = .707) giving 4 breaks of 70.7% of the peak value per cycle. (70%, 70%, 
70%, 70%)

6 electrodes can be phased to fire at either 200 useful bps (0%, 86%, 86%, 
0%, 86%, 86%) or at 300bps (70%, 100%, 70%, 70%, 100%, 70%) or somewhere in 
between.

8 electrodes can be phased to fire at either 400bps (38%, 92%, 92%, 38%, 
38%, 92%, 92%, 38%) or at 300 useful bps (0%, 70%, 100%, 70%, 0%, 70%, 100%, 
70%) or somewhere in between.

I have calculated the differences in possible power transfer for each 
combination taking into account that the fact when using a fixed load the 
change in power is proportional to the square of the change in voltage (P=E 
squared / R). Using 2 electrodes at 100bps as a reference: I found that 
using 4 electrodes would give the same power transfer at 100bps (2x 100%) or 
200bps (4x 70%). 6 electrodes will give between 1.5 times and 2 times 
depending on phasing. 8 electrodes will give 2 times more power regardless 
of the phase adjustment.

So is it better to use 4 electrodes giving 4 firings per cycle at 70% of the 
peak or 2 breaks approaching 100% of peak considering the power transfer 
calculates to be the same?
Or go for more electrodes giving more BPS and higher power transfer?
Comments from experienced SRG builders welcome.

Thanks in advance,
Paul A




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