Potentiometer rotational torque
Archiver
Posts: 46,084
I was talked out of making my own pressure gauge for 1,000's of psi- the
safety issues prevailing. Someone offeredthe idea of hacking a mechanical
gauge mechanism, coupling it to a pot, then into an A/D.
Now I have a very small shaft (which the needle-type dial indicator was once
pressed on to) that I want to couple to a pot shaft. I have checked the
vaiety of pots in my parts drawers and toy box, and they all seem to require
more rotational torque than I would like to apply with the tiny mechanism. I
want to find a type of pot that is easy to turn.
I have searched the catalogs hoping to find some kind of designation that
might apply - to no avail.
Does anyone have any clues that may help me along with this???
TIA,
Chris
safety issues prevailing. Someone offeredthe idea of hacking a mechanical
gauge mechanism, coupling it to a pot, then into an A/D.
Now I have a very small shaft (which the needle-type dial indicator was once
pressed on to) that I want to couple to a pot shaft. I have checked the
vaiety of pots in my parts drawers and toy box, and they all seem to require
more rotational torque than I would like to apply with the tiny mechanism. I
want to find a type of pot that is easy to turn.
I have searched the catalogs hoping to find some kind of designation that
might apply - to no avail.
Does anyone have any clues that may help me along with this???
TIA,
Chris
Comments
large gear you will get a significant torque advantage, but you may lose some
range depending on the number of rotations your pot is capable of turning.
I think a better option would be some kind of optical shaft encoder. They make
them with patterns so that the angle of the shaft can be determined, and their
output is digital. Hope this helps,
Dan Fox
"Chris Loiacono (E-mail)" <chris01@t...> wrote: I was talked out of
making my own pressure gauge for 1,000's of psi- the
safety issues prevailing. Someone offeredthe idea of hacking a mechanical
gauge mechanism, coupling it to a pot, then into an A/D.
Now I have a very small shaft (which the needle-type dial indicator was once
pressed on to) that I want to couple to a pot shaft. I have checked the
vaiety of pots in my parts drawers and toy box, and they all seem to require
more rotational torque than I would like to apply with the tiny mechanism. I
want to find a type of pot that is easy to turn.
I have searched the catalogs hoping to find some kind of designation that
might apply - to no avail.
Does anyone have any clues that may help me along with this???
TIA,
Chris
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and Body of
the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
[noparse][[/noparse]Non-text portions of this message have been removed]
gauge face has about the same useable angle as a single-turn pot.
Optical is certainly the most reliable method to use, but I have avoided it
because of certain process limitations. This design is battery powered, and
needs to run only when there is pressure applied, ie: when the sensor or
gauge is connected to a pressurized line or tank it will turn on and start
transmitting pressure data. When removed from the pressure source it will
turn off. With an optical encoder, I don't know of a way to accomplish this
while maintaining a consistent reference.
If I can't get past the mechanical requirement of the pot, I will go to
optical with an on/off switch, which I am hoping to avoid....auto on/off is
much more desireable.
c
>
> It sounds like you may need to add some kind of gear to the
> gauge shaft. With a large gear you will get a significant
> torque advantage, but you may lose some range depending on
> the number of rotations your pot is capable of turning.
> I think a better option would be some kind of optical shaft
> encoder. They make them with patterns so that the angle of
> the shaft can be determined, and their output is digital.
> Hope this helps,
> Dan Fox
sensor. Digikey sells some pressure sensors that will handle 2500psi. Then
find a pressure switch for the range of pressure you are trying to measure,
when the pressure builds up it kicks on the battery powered device.
Original Message
From: "Chris Loiacono (E-mail)" <chris01@t...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, April 15, 2002 10:56 AM
Subject: RE: [noparse][[/noparse]basicstamps] Potentiometer rotational torque
> There is not sufficient rotation to gear the motion downward. A typical
> gauge face has about the same useable angle as a single-turn pot.
> Optical is certainly the most reliable method to use, but I have avoided
it
> because of certain process limitations. This design is battery powered,
and
> needs to run only when there is pressure applied, ie: when the sensor or
> gauge is connected to a pressurized line or tank it will turn on and start
> transmitting pressure data. When removed from the pressure source it will
> turn off. With an optical encoder, I don't know of a way to accomplish
this
> while maintaining a consistent reference.
> If I can't get past the mechanical requirement of the pot, I will go to
> optical with an on/off switch, which I am hoping to avoid....auto on/off
is
> much more desireable.
>
> c
>
> >
> > It sounds like you may need to add some kind of gear to the
> > gauge shaft. With a large gear you will get a significant
> > torque advantage, but you may lose some range depending on
> > the number of rotations your pot is capable of turning.
> > I think a better option would be some kind of optical shaft
> > encoder. They make them with patterns so that the angle of
> > the shaft can be determined, and their output is digital.
> > Hope this helps,
> > Dan Fox
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
actuate a reed switch? If the magnet is at the low reading of the gauge it
should keep everything off when there is no pressure, and then turn on when the
needle rises.
Dan
"Chris Loiacono (E-mail)" <chris01@t...> wrote: There is not
sufficient rotation to gear the motion downward. A typical
gauge face has about the same useable angle as a single-turn pot.
Optical is certainly the most reliable method to use, but I have avoided it
because of certain process limitations. This design is battery powered, and
needs to run only when there is pressure applied, ie: when the sensor or
gauge is connected to a pressurized line or tank it will turn on and start
transmitting pressure data. When removed from the pressure source it will
turn off. With an optical encoder, I don't know of a way to accomplish this
while maintaining a consistent reference.
If I can't get past the mechanical requirement of the pot, I will go to
optical with an on/off switch, which I am hoping to avoid....auto on/off is
much more desireable.
c
Do You Yahoo!?
Yahoo! Tax Center - online filing with TurboTax
[noparse][[/noparse]Non-text portions of this message have been removed]
line, the wheel turns to reflect the pressure very quickly - probably in
usec's. At some point in the rotatation, the controller would come alive, no
doubt having missed the zero reference altogether. I suspect it would read
differently each time it was started.
C
>
> What if you attached a magnet to the wheel of the optical
> encoder and used it to actuate a reed switch? If the magnet
> is at the low reading of the gauge it should keep everything
> off when there is no pressure, and then turn on when the
> needle rises.
> Dan
>