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Re: [TCML] Proudly presenting My first coil
John, Phil,
thanks for your remarks!
I'm aware of the break rate as you both mentioned.
On the first disc I only had 4 electrodes and phase tuning was pretty
critical. And the 2 HP engine weighing 17kg wasn't practical and I realized
it took its share of amps from the 16 available.
So I modified a smaller 0,5 HP motor (milled 2 flats on the rotor) and made
a new disc, which can hold up to 12 electrodes, to experiment with number
and offset positions. If you would take a look to the 2 previous videos,
you'll hear the first SRSG with only 4 electrodes. If you compare it to the
sound of the current gap, the pitch is about the same, that's why I
suspected the "missed" firings, so these missed electrodes are practically
redundant.
Due to a worn bearing and some inbalance perhaps in the smaller motor, each
revolution is slightly irregular, (producing the whieHIEhieHIE sound), but
it does run at 3000 rpm in synch according to my strobe.
Bottle caps become cheaply available, the next 36 bottles are under
development, as I'm drinking beer lol.
Mark
Phil, Mark,
Mark is using 12 spinning electrodes so his system is a "high break rate"
SRSG. Although it's more common for a SRSG system to be built to fire at
100
or 200 bps (low break rate), it is possible to use higher break rates. The
higher
break rate is needed if the capacitors are small, to get sufficient power
throughput.
It's always been my view that SRSG's don't offer much advantage over 200 or
240 bps, but still the higher break rate might offer somewhat smoother or
steadier
operation compared to an async system.
With 12 spinning electrodes, the setting of the phase probably makes very
little
difference to the operation of the coil. With 12 spinning electrodes, it's
unlikely
that all of them can fire no matter how the phase is adjusted. On Mark's
coil
it's possible that basically the gap might be firing on *every other*
electrode
presentation. It might be skipping some firings all along.... again
depending
on the capacitor size and motor rpm, etc. To me the sound sounds like about
maybe 400 bps or so? Even if a high bps SRSG fires on most of the electrode
presentations, it's likely that one or two that occur near the AC crossing
of
the power line charging voltage will fail to fire... there won't be enough
voltage
at that time to fire the gap. This will depend on gap spacing and many
other
factors too.
In Mark's coil, I seem to hear a beat of about 1/2 second. I wonder if the
rotary is actually running at synch speed? Although I realize it's a proper
synch-type motor, the air-resistance loading of the rotor and electrodes
may be
preventing the rotary from actually obtaining synch-speed? Mark did you
verify true sync operation using an o'scope locked to power line, or
a strobe of some sort?
In closing let me say that the coil runs very nice and smoothly overall,
with
nice streamer behavior. Truly a very good job on your first coil !
Cheers,
John
2012/5/6 Philip <phil@xxxxxxxxxxx>
> John, Mark.
> Yes....I had overlooked the 12 electrode configuration in the OP!
> This would be giving 600bps, however despite being 3 times more than mine,
> I
> would have still expected to hear some drone, but as mentioned, some
> presentations are most likly not firing.
> On 200bps I can get a very noticable differance in the sound of the coil,
> in
> fact I tend to use the sound alone to get the right phase position using
> John's circuit.
> Interesting point on the benifits, or not, at higher bps. As you say
> probably little benifit over a much simpler ASRSG, but I also think it
> helps
> to give a nice snaking motion to the streamers, well I put my streamers
> action down to it being synchronous at any rate.
> If you do get more caps one day, then halving the flying electrodes may be
> worthwhile, along with building John's circuit to control things.
> Phil
>
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
> Of Futuret
> Sent: 06 May 2012 16:39
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] Proudly presenting My first coil
>
> Phil, Mark,
>
> Mark is using 12 spinning electrodes so his system is a "high break rate"
> SRSG. Although it's more common for a SRSG system to be built to fire at
> 100
> or 200 bps (low break rate), it is possible to use higher break rates. The
> higher
> break rate is needed if the capacitors are small, to get sufficient power
> throughput.
>
> It's always been my view that SRSG's don't offer much advantage over 200 or
> 240 bps, but still the higher break rate might offer somewhat smoother or
> steadier
> operation compared to an async system.
>
> With 12 spinning electrodes, the setting of the phase probably makes very
> little
> difference to the operation of the coil. With 12 spinning electrodes, it's
> unlikely
> that all of them can fire no matter how the phase is adjusted. On Mark's
> coil
> it's possible that basically the gap might be firing on *every other*
> electrode
> presentation. It might be skipping some firings all along.... again
> depending
> on the capacitor size and motor rpm, etc. To me the sound sounds like
> about
> maybe 400 bps or so? Even if a high bps SRSG fires on most of the
> electrode
> presentations, it's likely that one or two that occur near the AC crossing
> of
> the power line charging voltage will fail to fire... there won't be enough
> voltage
> at that time to fire the gap. This will depend on gap spacing and many
> other
> factors too.
>
> In Mark's coil, I seem to hear a beat of about 1/2 second. I wonder if the
> rotary is actually running at synch speed? Although I realize it's a
> proper
> synch-type motor, the air-resistance loading of the rotor and electrodes
> may
> be
> preventing the rotary from actually obtaining synch-speed? Mark did you
> verify true sync operation using an o'scope locked to power line, or
> a strobe of some sort?
>
> In closing let me say that the coil runs very nice and smoothly overall,
> with
> nice streamer behavior. Truly a very good job on your first coil !
>
> Cheers,
> John
>
>
>
>
>
>
>
> -----Original Message-----
> From: Philip <phil@xxxxxxxxxxx>
> To: 'Tesla Coil Mailing List' <tesla@xxxxxxxxxx>
> Sent: Sun, May 6, 2012 8:40 am
> Subject: RE: [TCML] Proudly presenting My fist coil
>
>
> Hello.
> Nice streamers but it didn't seem to have the right sound for a synchronous
> RSG. You tend to get more of a drone normally like this (skip intro)
> http://www.youtube.com/watch?v=rZSiM7VeMjI If the phase was out it might
> also account for the "not firing on all the electrodes" that you mention,
> as
> the cap is not charged at presentation. What are you using for phase
> control?
> (Nice to see a 'classic' coil being built instead of SS) (Cd 942 caps would
> improve things as well, and the coil seems worth the expense)
>
> Phil
>
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
> Of SusaX2 X2
> Sent: 05 May 2012 22:32
> To: Tesla Coil Mailing List
> Subject: [TCML] Proudly presenting My fist coil
>
> Hi to all fellow TC enthusiasts!
>
> Without further ado, I present to you, my first Tesla Coil:
> http://www.youtube.com/watch?v=OJAVul8r7D8
>
> very eager to hear your comments, remarks and or jokes about this one!
> It's a genuine junk box coil, after watching the video, some might say it's
> a coil in a pile of junk. No offence taken.
>
> I'm a dutch mechanical engineer and slightly mad, so I guess I fit just
> about in here.
> I'm aware coiling is potentially very dangerous, I'm also aware coiling is
> very possible.
>
> About the coil:
>
> The control box is plugged in a 3 phase wall socket, each fase is 220V and
> 16A. The power-on button actuates the 3 phase relay for the synchronous
> spark gap induction motor, which is modified to salient pole operation at
> 3000 rpm. It has 1 pair of stationary electrodes and 12 flying brass
> electrodes, but I don't think it fires on all of them.
>
> For the power supply only 1 phase is used by the 6A Philips variac. Then I
> connected an overdimensioned home made line filter, 48 uF PFC and a
> ballast made from a demolished welder. This limits the current to 6,3A, so
> the quad MOT stack doesn't melt my variac.
>
> The capacitor is a SWC with 72 beerbottles, about 45 uF.
> The primary is a copper ribbon pancake, tapped at the 7th turn.
> The secondary is a 125mm PVC pipe with 830 turns of 21 AWG wire.
> The top load is a 350x80mm and a 500x120mm toroid, both styrofoam with alu
> tape and quite smooth. Best performance is with no breakout point.
> RF-ground is a 3 meter steel pipe hammered into my back yard.
>
> With the dual MOT stack, it produced 1 meter long sparks and a distinct
> ozone smell. Now, with the quad MOT stack, sparks measure over 130cm and
> the stench is more than alone ozone. It scrares the hell outta my wife, so
> mission accomplished lol.
>
> Greets from Holland,
>
> Mark
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