That's why I've gone to a dc Tesla coil, which takes care of most all of
the problems that can occur with an ac coil. I've finally have my pole
transformer operating as a dc coil and I'm very pleased with its
performance. Charles Rakes
On Wed, Mar 28, 2018 at 4:03 AM, phil <pip@xxxxxxxxxxx> wrote:
>
> Steve
> As 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
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>>
>
> --
> Regards Phil www.hvtesla.com
>
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