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RE Re: Variac vs. Fan spe

Subject:       RE Re: Variac vs. Fan spe
       Date:   Mon, 05 May 1997 16:13:44 GMT
       From:  robert.michaels-at-online.sme-dot-org (Robert Michaels)
Organization: Society of Manufacturing Engineers
         To:  tesla-at-pupman-dot-com


T>>         You are =so= close to the truth - it's a pity you don't get
T>>         the cigar:

T>Thats ok Robert, I hate all tobacco smoke! Ironicaly I used to be a
T>moderate to heavy smoker and I tried to quit for close to 30 years!
T>(I started when I was 9 years old) I had to go into a coma to get off
T>the suckers, I sware there more addictive than heroin! I havent
T>touched any tobacco products in almost three years AND I DON'T MISS
T>IT ONE BIT!

        Congrats on breaking the habit (tho the comparison with
        Heroin addiction is a bit strained!).  I don't actually
        smoke cigars, but once in a while I do like to hold one
        in my mouth or hand.  I like the intimidation factor.
        Especially with those of crown imperial length!


 [ ... ]

T>Actually synchronous motors like what used to be used in old turn
T>tables and clocks work admirably with VFD, many amateur astronomers
T>build their telescope clock drives (to keep the telescope pointed at
T>an object for a prolonged time) with synchronous motors and use VFD
T>to adjust their speed for planets vs stars or the moon.

        I had forgotten about synchronous motors.  Thanks for the
        re-mind.  For that matter there are inherently slow-turning
        synchronous motors:  The Slo-Syn line by Superior Electric.

        Scarce animal tho, especially in sizes to do useful work.



T>>         The best quick-and-dirty source for universal motors with
T>>         good speed characteristics is to salvage one from an old
T>>         vacuum cleaner.
T>>
T>>                 Such motors can also be begged from vacuum
T>>                 cleaner repair shops in the same manner as
T>>                 neon transformers.
T>>
T>>         They can be controlled as-is by means of a Variac, or
T>>         with a dc power supply + Variac a very fine degree of
T>>         control may be realized.

T>Lets not forget old AC power tools; drills, circular saws, ect almost
T>always used universal motors. Universal motors also work very well
T>with the triac phase shift controls commonly sold as light dimmers
T>and they are very inexpensive!

        May/may not be as good a source as vacuum cleaners.  In some
        cheaper products, motor is integral with case and/or gear
        train.  Hard to extract.  Can be difficult to mount if motor
        is indeed separable intact from case of the tool.

        The trigger speed control in variable-speed electric drill
        motors, etc. is a triac circuit, but --

        Nicht gut mit der solid-state shtuff mit den Tesla-coilen.
        Too sensitive to stray fields and induced rf.  That's why
        I said "Variac" in my post.

                                        Slow and steady, in ---
                                        Detroit, USA

                                        Robert Michaels