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Re: The 1500t secondary myth (long)



Original poster: Dave Leddon <leddon1@xxxxxxxx>

Steve,
Try www.surpluscenter.com for DC treadmill motors. I purchased two 2 HP 130 VDC motors from this outfit both of which made great async gaps. I mounted a fairly heavy FR4 rotor directly on the motor shaft and haven't experience any bearing problems as yet although I was cautioned by Dr Resonance that these motors might not last long in this application. In reality, I don't think most of us rack up that many hours of run time to be concerned about bearing longevity.
Dave
Pleasanton, CA


At 06:34 PM 12/6/2004, you wrote:
Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx>

D. C.,

I am getting tired of the loud gear growling from my angle grinder powered
ASRG, and have been thinking of going the treadmill motor route.  What are
your surplus sources for these motors?  Are the motor bearings good enough
(e.g. very little axial motion) to mount the rotor directly on the motor
shaft?
Thanks,
--Steve Y.

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, December 06, 2004 11:41 AM
Subject: Re: The 1500t secondary myth (long)


> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx> > > > > > One "tunes" a sparkgap by adjusting the dwell time. This is usually > done by using a DC motor for the drive and then adjusting it's speed > with a small variac/rectifier/cap combination. We use a lot of > the "tredmill" type motors available surplus. We use 3,000 rpm motors > with a 1-2 HP rating. We usually mount the spark gap rotor in a pillow > block configuration so we can change pulley sizes to adjust the rotor > speed in a range that is most effective. > > You can also put a spark on both sides of the rotor and connect them in > series. This is usually done at power levels above 7.5 kVA to provide > additional quenching. You can also experiment with using one side of > rotor (dual gap) or both sides of rotor (quad gap) to see the effect of > quenching on your system. Use a dual gap if possible at lower power > levels so you don't end up wasting all your energy in the form of heat > and light in the sparkgap. > > Dr. Resonance


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David H. Leddon
Lawrence Livermore National Lab
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Livermore, CA 94550-9516
leddon1@xxxxxxxx
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