SteveAs your running the 60Hz equivalent of my own coil setup in the UK (200bps @ 50Hz), you should, when correctly in phase, have four firing peaks of equal voltage. This gives a very distinct, characteristic sound or 'drone' to the coil, and is what I use to find and set the correct position. (only works on 200bps , and to a lesser extent on 400bps, 100bps always having a 'rasp' sound to it regardless, and 300bps always sounding 'ragged') Listen to when my coil (deliberately started out of phase) is put onto phase at 55 seconds in (link starts at 45 seconds): https://youtu.be/yRBqDZCP0jc?t=45 ; Also the same later on where I put it out of phase to make it hit the floor more: https://youtu.be/yRBqDZCP0jc?t=234 ; (it happens at 4:05) You should be hearing a difference on yours though, if all is correct. You will get some voltage reversal though, as the firing point when all the caps voltage peaks are equal is after the sine wave peak. As John says if you tune it enough off phase you can get a 'pseudo' 100bps setup, but having two high peaks and two low ones per 60 Hz cycle. This may over volt the caps though, so I wouldn't recommend it. I would check with a strobe that you are getting the full 90 degrees shift you need, if not you could find the area you want is just out of reach. Bear in mind though (or you may have already found out) that getting the full 90 degree shift is achievable only at the cost of having a higher than comfortable voltage (from the motor's point of view) being fed to it. On a 240v UK set up I've measured as much as 270+ volts being fed to the motor with the wrong cap values in place, so that's a good way to kill a motor if you're not careful.
(Once you do find the sweet spot it's best to move the disc on the motor's shaft so that the best position is midway in the sweep of the phase controller.)
Phil Tuck On 27/03/18 04:52, Steve White wrote:
I have had my big SGTC running for about 9 months now. Here are the salient specs: * 8.6" x 39" secondary * 9" x 30" top load * 45 nF of primary circuit capacitance * RSG with 4 rotating electrodes and 2 stationary electrodes, 3600 RPM, 240 breaks per second (4 per 60 Hz cycle at 0, 90, 180, and 270 degrees) * Pole pig as power source * 4800 watt wall power * Maximum spark length is about 8 feet I also built an electrical phase shifter, as others have, based on a variac and capacitors. I confirmed with my oscilloscope and an optical sensor that I can get about 0 to 90 degrees of phase shift by turning the variac knob. Before I added the phase shifter, I used an optical sensor and oscilloscope to accurately set the firing points at 0, 90, 180, and 270 degrees of each 60 Hz cycle. My question concerns the apparent non-effect of the phase shifter on spark length. With the coil running, as I adjust the phase shift, I see no apparent change in the spark length. Does anyone have any thoughts as to why this would be? I am perfectly satisfied with the coil's performance, I just can't explain the apparent non-effect of the phase shifter. Steve _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla
-- Regards Phil www.hvtesla.com _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxxxxxx https://www.pupman.com/mailman/listinfo/tesla