Re: hamfests, rotors, protection

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Matt Skidmore by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <fox-at-woozle-dot-org>
> 
> i went to a small indoor hamfest over the weekend and picked up a few
> goodies at a very low price, but i had some questions about adding them to
> my coil.
> 
> i got 5 wirewound resistors for 50 cents. these are 2 ohm and i'd guess
> about 75 to 100 watt each. a gree ceramic type. i dont have the money to
> build a nice NST protection filter so i was thinking about using two of
> these resistors in paralell accross each leg of the NST, with of course, a
> safty gap. i know this isnt the best solution but wanted some comments,
> maybe an idea of what to do with that extra resistor. they're only 2 ohm,
> is that enough?

	They will certainly protect the transformer, but you won't get any
power out!  For example, 60 mils times two ohms would result in only
0.12 golts!  If instead you mean to put them in series with the safety
gaps, they are too small to do anything at all.

> also while i was there, someone gave me a brand new sync motor. i cant
> tell if the hp is 1/3, 1/30, or 1/300. its 900 rpm. 

	900 RPM would mean an eight-pole motor, a bit unusual.  You should be
able to get at least an estimate of power by comparing its weight with
that of some motor whose rating you know.  A 1/3 HP single-phase sync
motor would be pretty darn large.  For instance, 1/30 HP syn chronous
teletype motors weight around 10 pounds.

i wanted to know what
> the calculation is for creating a rotor for this. how big does the
> rotorneed to be and spacing of the electrodes. this motor has 3 wire,
> yellow, red, and green. i assume red is hot yellow is the other side and
> green is ground, but whenever i plug green to ground the motor stops and
> is quite hard to turn. i was thinking that maybe green is the start
> circuit? when i plug it in i usually have to give the motor a spin before
> it starts. so i read that some motors have a start circuit.
> 
> thanks!

	Suspect you have a capacitor start (& run?) motor.  Don't know if
there's any universal color code, so don't know where you go from here. 
Someone probably will.
> 
> -fox

Ed