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Re: desperate need for info on sync gaps
Hello Chester.
On Sat, 23 Oct 1999 10:38:58 -0600 Tesla List <tesla-at-pupman-dot-com> writes:
> Original Poster: chester lowrey <lowrey-at-interpac-dot-net>
<snip>
> but the design also called for a 120bps sync rotary gap which i
> feel is
> was to hard to find info about.
I was lucky enough to be paying attention quite some time ago when there
was a slew of discussion as to the methods involved, and built one of it.
Not nearly as hard I had imagined.
i know all basic construction
> methods for
> rotary but dont have the slightest idea of how to modify a standard
> ac
> motor to syncronous operation.
You need to look for a medium to low hp AC induction motor.. mine was
labled 'split phase induction motor' and had an original speed of
1725rpm, and the modification locked this to 1800rpm. It was a 1/3hp,
others have used 1/4, 1/2, 3/4, 1+ or anything around there succesfully.
i have a vacume cleaner motor, a very
> well
> made brushless ( can you use brushless) 1/6 hp 3500 rpm 60hz motor,
You need to use brushless motors. A 1/6hp 3500 rpm motor could be
modified for AC sync 3600rpm, and with two electrodes on the rotor you
could get 120bps. The higher speed presents greater mechanical problems,
though, and the low hp (which will be lessened even more through the
modification) may not be enough keep the rotor speed up, falling out of
sync periodically.
> and a
> blender moter of unknown value. is it possible and if so worthwhile
> to
> modify them to sync operation because i already built a async
> rotary with
> poor results although that motor died due to arcs to its shaft and
> may be
> possible to repair but i havent looked into it yet. and i do also
> have
This is from a previous post of mine, beginning by describing the innards
of an induction motor:
The key ID is the fact that the rotor will have no windings on it, and no
commutator. These motors tend to be quiet in operation. Look for motors
larger than 1/3 hp. Since in the conversion, a good deal of that hp will
be lost.
After removing the rotor, there will be a fairly large, regular
cylndrical section that is normally in close proximity to the coils
withing the motor case. This is what needs to have four "flats" machined
into it. I used a mill to cut them, but a lot of people have used hand
files, disk sanders, and anything thier imagination says will work. The
material is mostly aluminum, so it will be easy to machine. four flats,
evenly spaced around the curved surface of the cylinder, should be cut
about 1/16" to 1/8" in depth. This means that four lengthwise flat
sections will be filed into the rotor, with 1/16" to 1/8" of material
removed. light colored bands of metal will be seen at an angle after the
top payer of the rotor is filed off. Try not to cut completely through
any of them.
After you perform the modification, a good way to test whether it is
spinning in sych in with a non-phosphorus containing neon sign. It will
produce 120 pulses of light per second, and if you draw two thick black
lines perpendicular to each other accross a disk face attched to the
motor, the lines will appear to stand still. I've done this with neon
lights, mercury vapor tubes, and diodes powered with an unfiltered
half-wave rectifier.
I used a 1/3 hp salient pole induction motor, and it is working fine with
a 6" rotor.
>
> ps. what exactly are the characteristics of a sync
> moter ie. is it in
> time with the 60 hz that it and the xfmr run off so you have to
> place the
> electrodes in precise orientation to the brushes or something so
> they
> connect just as the polarity is about to reverse and discharge the
> cap ? ?
> or am i completely lost.
Not entirely;) The rotor becomes 'locked' into the rotating magnetic
field, the movement of which is directly controlled by the mains
frequency. In that the rotation always matches the line frequency, so the
rotor will always be in the exact same spot for any given point of the 60
sine wave.
i do have acess to many tools cus my dad is
> mechanic and wood worker so modifying to motor might be fairly easy.
> oh and
> about that 12/30 coil design would it run properly on a static gap
> like the
> one i currently have
The 12/30 coil uses a lerger than resonant capacitor, which, for the most
part, will work well only with the SRSG. I've tried running an LTR system
with an RQ gap, and it really didn't work well at all.
>
> very much thanks in advance Chester Lowrey
>
>
Grayson Dietrich
http://www.electrophile.8m-dot-com
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