If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Most AC and DC motors can be run on the bench, or in the lecture hall, without electronic supporting equipment. At most, a capacitor for some AC types.
I used to think that common stepper motors are an exception. Collected some parts for a driver involving microswitches instead of transistors, and one or more cams on a hand-cranked shaft. Much less flexibly, I bet most scrounged steppers can be demonstrated using low voltage AC with a capacitor for phase shift, as in the seminal Slo-Syn units.
Then realized there's a simpler way to generate the requisite two-phase AC power: twist the shaft of another common stepper motor. Made this demo a few years ago. Its 4-wire connecting cable came from the same dead printer, so no wire cutting or soldering was needed. The slave shaft (worm) runs in either direction, without slipping, if the master (stubby pinion) is turned fast enough. The little generator-motor set turned up last Friday as I prepared for the Saturday hamfest, reported in a different thread. Served as a show-and-tell curio.
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600
Doesn't this rely on the residual magnetism in the stepper motors?
Some usage situations can zero this out; if that happens it won't self-start.
You're normally better off having one of the motors being a permanent magnet AC motors; that way, provided the currents are kept at sensible levels, the magnets will not degauss and you can always start it.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Selsyns transmit rotational position between units. Military used them for years as indicators. However, they have a strange mode. If the shaft of one unit is held fixed, and the other unit is driving an unbalance mass, i.e. a pointer, the free shaft unit can be shocked into rotation, electrically or mechanically. This irked the operators of very large machinery, and electricians were called to correct the situation.
The slo syn motor has a toothed magnetized rotor and are designed as a split phase slow speed, high torque motor. They will run at a synchronous speed governed, (within reason) by the line frequency. They also offer a degree of holding torque. The capacitor has to be in the ballpark of what is called for.
As with much old junk electrics, the oil capacitors may contain pcb oils.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Running stepper motors without using semiconductors
