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Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous Motor

Hello,
today I modified a 400W universal motor from a washing machine. I used 2 diodes each 1kV/6A. I did a scope test which shows that the motor runs perfectly sync: 

http://www.youtube.com/watch?v=yOlfzxzucy8
But there are 2 problems: The motor is not self-starting AND the motor sometimes runs in "crazy mode", as I call this strange behaviour. "normal-mode" and "crazy-mode" - both can be seen in the video. 

Best Regards
Stefan
----- Original Message ----- From: "Clive Penfold" <clivepenfold@xxxxxxxxxxxxxx> 
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, December 07, 2010 6:46 PM
Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous Motor 


Phil,

Yes, that is correct. Brief explanation along with some photos here:

http://4hv.org/e107_plugins/forum/forum_viewtopic.php?102515.last

Regards,

Clive




________________________________
From: Phil Tuck <phil@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tuesday, 7 December, 2010 15:10:17
Subject: RE: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous Motor 

DWP,
I think there is some misunderstanding here. I don't think the sensor and magnet 
were triggering the strobe as you do (I think that is what you're thinking?)
The presumption is that the magnet was attached to the motor shaft such that it 
passed and induced a voltage into a fixed coil once per rev.
If so, the output will always coincide with the electrode passing that point in 
space.
If the scope is setup to show both channels overlaid, and the output from the sensor coil is fed into one channel, with the mains fed in on the other channel, and the output from the sensor subsequently always coincides with the same point 
on the mains sine wave, then the motor is synchronous.


I use an infra-red sensor being tripped by the electrodes and it work fine.

Regards
Phil

www.hvtesla.com

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of 
dave pierson
Sent: 07 December 2010 12:34
To: Tesla Coil Mailing List
Subject: Re: [TCML] How To Turn A Vacuum Cleaner Motor Into A Synchronous Motor 


The poster mentions that he had "the mains on the other" [ channel] So
I assume a mains reference sine wave on the other channel.

     Good point.  However:


In usual engineering use of the term synchronous motor, the speed is
set by the line frequency.  Strobe Testing with a magnet spun by the
same motor as a sync source demonstrates that one end of the motor
(where the magnet is) is 'synchronous' with the other end.



If a scope is to hand: most have a 'line sync' position, which syncs
the scope to the _line_ freq.  With line sync selected, a reading
from the flying magnet to a sense coil would be interesting.



A motor which (happens?) to be running at 3000 (ish) will appear
synchronous to 50 (or 60, or 30 or 100).  A proper synchronous motor
will hold synch Under Varying Load.

    The key is just above.  a 'truly synchronous' motor will
    hold speed, and phase, under varying load and input
    voltage, (within reason...).

    best
     dwp
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