All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.

wrote:
All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.

What kind of rheostat? What kind of motor?

A rheostat, of the type used in an old sewing machine pedal, will only
properly control the speed of a universal (series-parallel wound) motor (AKA
AC/DC motor) or a straight DC motor (the kind with brushes).

Beyond that, you need to select a rheostat with current capacity greater
than that of your motor, and ideally, several times larger (a slower running
motor will consume more current than a motor running at full speed).

Jon

On Aug 2, 12:01*pm, " wrote:
All the packages ive looked at *in the store mention 115 v. *, but
none mention 12 vdc. * *Please advise. *Thanks.

I havnt seen a Rheostat sold in hardware stores for years, A Rheostat
will work.

wrote:
All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.

A wire-wound rheostat of the appropriate wattage will do
fine. An electronic speed control mentioned by another
poster is more efficient because it can lower the speed
but keep the torque fairly constant. You may obtain a
speed control from a broken cordless 12 volt drill and
it would work. You could check pawn shops or even call a
couple of construction companies to see if they have any
worn out cordless drills. You could also drop by your
local Dewalt or Skill repair depot and ask them if they
have any in their trash heap.

TDD

On 8/2/2009 10:01 AM spake thus:

All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.

Both of these places have rheostats for sale for cheap; just do a search
for "rheostat":

Electronic Surplus Inc.-- http://www.electronicsurplus.com
Alltronics-- http://www.alltronics.com


--
Found--the gene that causes belief in genetic determinism

Old auto car heater switch !!
Jerry


http://community.webtv.net/awoodbutc...oodWorkingPage



http://community.webtv.net/awoodbutcher/1974RuppCentair

Of course it can be applied.

Now. What did you want it to do? Depending on what you want
it to do, it might work or not.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


" wrote in message
...
All the packages ive looked at in the store mention 115 v.
, but
none mention 12 vdc. Please advise. Thanks.

wrote:
All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.
I think you've been looking at AC lighting dimmers - these are not
rheostats and won't work on DC - 12 volt or 115 volt.

On Sun, 2 Aug 2009 10:01:23 -0700 (PDT), "
wrote:

All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.

I used one of these on a 1/4 hp motor.
http://www.bakatronics.com/shop/item.aspx?itemid=581

On 8/3/2009 9:11 PM spake thus:

On Sun, 2 Aug 2009 10:01:23 -0700 (PDT), "
wrote:

All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.

I used one of these on a 1/4 hp motor.
http://www.bakatronics.com/shop/item.aspx?itemid=581

Looks to me like it uses PWM (pulse-width modulation), basically
"chopped" DC with variable duty cycle. Just curious: what kind of 1/4 hp
motor? Must be a 12 or 24 vdc one, obviously.


--
Found--the gene that causes belief in genetic determinism

David Nebenzahl wrote:
On 8/3/2009 9:11 PM spake thus:

On Sun, 2 Aug 2009 10:01:23 -0700 (PDT), "
wrote:

All the packages ive looked at in the store mention 115 v. , but
none mention 12 vdc. Please advise. Thanks.

I used one of these on a 1/4 hp motor.
http://www.bakatronics.com/shop/item.aspx?itemid=581

Looks to me like it uses PWM (pulse-width modulation), basically
"chopped" DC with variable duty cycle. Just curious: what kind of 1/4 hp
motor? Must be a 12 or 24 vdc one, obviously.

That's what it is. It give much much more torque at low speeds vs
lowering the voltage. I think that one also allows you to vary the
frequency of the PWM, but I'm not sure why you would want to do that?

Tony