File puptcrit/puptcrit.0503, message 128


Date: Wed, 23 Mar 2005 19:10:54 -0500
To: puptcrit-driftline.org-AT-lists.driftline.org
Subject: Re: [Puptcrit] automated curtain question


> cut down the motor speed  to say 1-2 revolutions
> per minute. or maybe someone has a better idea without  resisters.

> Mark

  YOU SHOULDN'T TRY TO SLOW MOTORS BY CONNECTING A RESISTER!

  While you might be able to slow the motor a little bit, the more likely
results are a smoked motor and resister (depending on the motor, current,
etc.)  The potential heat generated warranted my all-caps warning above.

   There are two ways to get slower output from a motor.  Gearing, or
complex electronics.  Gearing is the obvious choice for most people.

  Where to get geared motors?  I don't know the kind of power you need for
your curtain, so that is the biggest issue.  Little gear motors can be taken
out of toy cars.  Bigger ones from the children's battery powered ride toys.
There are on-line stores for robot parts that hobbiest use. www.robotstore.com 

  The other issue I should mention is powering the motor.  Obviously, if you
have taken a motor from a battery powered device, you can power it by
batteries that add up to the same voltage.  But, if you want to power it
from a wall outlet, there are other factors that must be considered (let me
know if you want me to go into that).

  Finally, DC motors tend to make a lot of electrical noise that your
amplifier could pick up.  There are ways to prevent this if you want me to
go into it.

Here are some links to find gear/motor units;

www.robotstore.com 

http://www.lynxmotion.com/Category.aspx?CategoryID=50

http://robotcombat.com/marketplace_motorsmisc.html

This is a site that sells surplus and used stuff
http://www.sciplus.com/category.cfm?subsection=18

Joe Dunfee  joe-AT-dunfee.com
Gordonville, Pennsylvania, U.S.A.

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