RE: [TCML] SRSG new video - tip for checking sync

["Stephen J. Hobley" <shobley@xxxxxxxxxx>]

It just occured to me that the little neon bulb in the Variac can work as a 120Hz strobe. I held the variac up to the rotor and indeed I saw the electrodes "freeze" when the sync was reached. It just can't quite get there in 120V output mode. 

The frozen electrode position is almost in the middle of two opposite quadrants - which by my reckoning must be about right.
I might add a couple of these neon bulbs (Radio Shack seem to have them) permanently to the SRSG for sync checking.

Useful for people like me - who can't find an old style flu tube anywhere.

Steve


www.stephenhobley.com
317 201 4281

The Laser Harp Project - www.stephenhobley.com/build



-----Original Message-----
From: tesla-bounces@xxxxxxxxxx on behalf of Stephen J. Hobley
Sent: Fri 8/29/2008 11:45 PM
To: Tesla Coil Mailing List
Subject: RE: [TCML] SRSG new video - feedback welcome
 
On the recommendation of a group member that my AC line voltage may well be below the 120v normal; I hooked the motor up to the Variac and this time flipped the output switch to 140V. Turning through the variac gave me the usual "hunting" sounds but then at about 90% it stopped hunting and gave a continuous tone - this looks like the 'sync' I need. So I guess my original SRSG configuration is not really an S-RSG after all. 

I need to get the AC voltage up to whatever the 140V setting on my Variac is putting out to get this motor to run synchronous.

The Terry filter safety gaps where definitely firing on Thursday night, there are some nice black circles on the brass spheres.

Thanks for all the feedback from the list - it really helps.

Steve

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx on behalf of bartb
Sent: Fri 8/29/2008 9:45 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] SRSG new video - feedback welcome
 
Hi Steve and Pete,

I'm inclined to agree with John F. The motor sounds as though it's not 
synchronous. The pulsing is a little faster than I'm accustomed to 
hearing, but your at 50Hz I think, so it would be a tad faster. The 
pulse is very steady and it doesn't sound like the gap is hunting. 
Hunting occurs in a synchronous gap when the motor torque is not quite 
enough to keep the disc rotating (due to the weight of the disc). But 
usually this type of pulsing is slower. This sounds like the gap is 
asynchronous and running maybe 1450 rpm. The reason is the pulsing and 
because I hear another much lower frequency in there as well as though 
the rotary is running through peak, across zero, back up to peak, etc.. 
over a slow period of time (like 6 cycles over the period of the video, 
thus 12 occurrences as the half cycles are what is heard). Are you sure 
this motor is synchronous? Is the an off the shelf sync motor or a 
home-brew type?

Regards,
Bart

Stephen J. Hobley wrote:
> http://au.youtube.com/watch?v=fkv9HdMF2yk
>
> This is another video of our attempts at setting the phase of our SRSG.
> It's getting better, but still a little bumpy.
>
> Are we close? Or is there something else wrong with gap spacing etc...?
>
> Thanks
> Steve and Pete
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