How to bring weights into the Stamp
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Hi, I am an art student and am currently working on a project involving the
basic stamp. I need my Stamp to detect how much weight is placed upon a
cushion. I have looked at electronic scales or making my own but I am
currently at a loss. Any cost effective ideas? I am looking at a weight range
from 50 lbs to 200 lbs approximately
basic stamp. I need my Stamp to detect how much weight is placed upon a
cushion. I have looked at electronic scales or making my own but I am
currently at a loss. Any cost effective ideas? I am looking at a weight range
from 50 lbs to 200 lbs approximately
Comments
Larry Gaminde
Original Message
From: "orangemarigold" <frlnmaiden@a...>
To: <basicstamps@yahoogroups.com>
Sent: August 29, 2003 11:09 AM
Subject: [noparse][[/noparse]basicstamps] How to bring weights into the Stamp
> Hi, I am an art student and am currently working on a project involving
the
> basic stamp. I need my Stamp to detect how much weight is placed upon a
> cushion. I have looked at electronic scales or making my own but I am
> currently at a loss. Any cost effective ideas? I am looking at a weight
range
> from 50 lbs to 200 lbs approximately
>
>
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>
frlnmaiden@a... writes:
> Hi, I am an art student and am currently working on a project involving the
>
> basic stamp. I need my Stamp to detect how much weight is placed upon a
> cushion. I have looked at electronic scales or making my own but I am
> currently at a loss. Any cost effective ideas? I am looking at a weight
> range
> from 50 lbs to 200 lbs approximately
>
>
Have you thought of adapting a pressure sensor?
Sid Weaver
W4EKQ
Port Richey, FL
[noparse][[/noparse]Non-text portions of this message have been removed]
are. However, I've heard that conductive foam will change resistance
under pressure. You know the black foam that they ship Ics in? So make
your pad out of that, attach a capacitor and use RCTime. I've often
thought about trying that for a project of the month, but I haven't done
it yet. I'm sure you'd have to calibrate it one of a kind, and the
accuracy can't be very good (nor the sensitivity).
Just a thought. A strain guage would be another way. Hack a bathroom
scale. Pressure sensor and an air column. I wonder if you could take the
kind of scale with a pointer (not a rotating wheel) and attach it to a
pot?
Al Williams
AWC
* Floating point math for the Stamp, PIC, SX, or any microcontroller
http://www.al-williams.com/awce/pak1.htm
>
Original Message
> From: orangemarigold [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=1ByBMoh8plkDJ7Tj2hmd4J27KrPuV8DHjqS2cDIMyCHGfXhr3jntUlHtfMwjginhe70yg7ISNN-UifE]frlnmaiden@a...[/url
> Sent: Friday, August 29, 2003 1:10 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] How to bring weights into the Stamp
>
>
> Hi, I am an art student and am currently working on a project
> involving the
> basic stamp. I need my Stamp to detect how much weight is
> placed upon a
> cushion. I have looked at electronic scales or making my own
> but I am
> currently at a loss. Any cost effective ideas? I am looking
> at a weight range
> from 50 lbs to 200 lbs approximately
>
>
> 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/
>
>
>
>
>basic stamp. I need my Stamp to detect how much weight is placed upon a
>cushion. I have looked at electronic scales or making my own but I am
>currently at a loss. Any cost effective ideas? I am looking at a
>weight range
>from 50 lbs to 200 lbs approximately
McMaster Carr http://www.mcmaster.com sells a couple of scales in the
$150 range that have an RS232 interface, easy to bring into the
Stamp. Part numbers 17295T31 and 17295T39.
-- Tracy
goes up to 100 pounds, but if that unit works in testing, you should be
able to substitute another in the same line that has a larger range.
http://www.parallax.com/detail.asp?product_id=30056
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: orangemarigold [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=H7H34VzzRG7u0B_pZ75Smj28mQv1Kk6UMrTCQ2MujSXsGP1-gVEGHKc0hC6p_VCfniB8rZxqrXY]frlnmaiden@a...[/url
Sent: Friday, August 29, 2003 1:10 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] How to bring weights into the Stamp
Hi, I am an art student and am currently working on a project involving
the
basic stamp. I need my Stamp to detect how much weight is placed upon a
cushion. I have looked at electronic scales or making my own but I am
currently at a loss. Any cost effective ideas? I am looking at a
weight range
from 50 lbs to 200 lbs approximately
To UNSUBSCRIBE, just send mail to:
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abuse@p....
I tried this thing with the black foam for shipping IC's using a multimeter.
With one multimeter pin on top and the other at the bottum of the piece of
black material the reading showed ca. 20 kOhm. By pressing it together
(squeezing between my fingers) the reading lowerd gradually down to ca. 1.5
kOhm as I increased the force.
I don't know about things like stability, linearity or repeatability of this
"device" but that may come with time.
Good idea for non-critical tasks I guess.
Klaus
>goes up to 100 pounds, but if that unit works in testing, you should be
>able to substitute another in the same line that has a larger range.
>
>http://www.parallax.com/detail.asp?product_id=30056
>
>-- Jon Williams
>-- Applications Engineer, Parallax
>-- Dallas Office
I used sensors like that (maybe not the same brand) in a wildlife
study a few years ago. The researchers wanted to put out a large
number (cheaply!) of feeding pans, and determine the approximate
weight of kangaroo rats that were visiting them. Each pan had three
of the thin resistive force sensors underneath a tripod base (made
with stick-on silicone feet). The assembly was only 1/4" thick.
The sensors are variable resistors, with F = 1/R (very
approximately). The three resistors connected in parallel have a
total resistance, R = 1/R1 + 1/R2 + 1/R3. The total force due to
weight is spread between the 3 support points, so the total force is
F = F1 + F2 + F3 =~ k/R1 + k/R2 + k/R3 = k*R. There was a big
temperature coefficient and mismatch effects and funny stuff, but it
did give useful results. At the time, I recall the sensors we used
cost less than the flexiforce sensors do now.
-- Tracy
>Hi,
>
>I tried this thing with the black foam for shipping IC's using a multimeter.
>
>With one multimeter pin on top and the other at the bottum of the piece of
>black material the reading showed ca. 20 kOhm. By pressing it together
>(squeezing between my fingers) the reading lowerd gradually down to ca. 1.5
>kOhm as I increased the force.
>
>I don't know about things like stability, linearity or repeatability of this
>"device" but that may come with time.
>
>Good idea for non-critical tasks I guess.
>
>Klaus
>
>
>To UNSUBSCRIBE, just send mail to:
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>Body of the message will be ignored.
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>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Forrest M. Mimms III describes an inexpensive simple pressure sensor, made
using the black I.C. conductive foam between sections of printed circuit
board in his "Engineer's Mini-Notebook -- Sensor Projects" booklet sold
through Radio Shack. See page 27.
Tim
Timothy Medema
CrystaLite, Incorporated
3307 Cedar St. (425) 745-6000 800-666-6065
Everett, WA 98201 Fax: (425) 257-0232
www.crystaliteinc.com
<mailto:timm@c...>timm@c...
The information transmitted is intended only for the person or entity to
whom it is addressed and may contain confidential and/or privileged
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this in error, please contact the sender and delete the material from any
computer.
I have played with this idea, having seen it in Mim's book. It does work,
but the resistance varies widely. How you connect to the foam is important.
I got the most consistant results using bronze mesh with conductive adhesive
(useful stuff). It was more reliable than bits of PC board. However, it
still varied day to day. There is also a long recovery period as the foam
re-expands to it's original shape.
Jonathan
www.madlabs.info
Original Message
From: "Timothy Medema" <timm@c...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, August 29, 2003 5:00 PM
Subject: RE: [noparse][[/noparse]basicstamps] How to bring weights into the Stamp
> At 11:49 PM 8/29/2003 +0200, you wrote:
> >Hi,
> >
> >I tried this thing with the black foam for shipping IC's using a
multimeter.
> >
> >With one multimeter pin on top and the other at the bottum of the piece
of
> >black material the reading showed ca. 20 kOhm. By pressing it together
> >(squeezing between my fingers) the reading lowerd gradually down to ca.
1.5
> >kOhm as I increased the force.
> >
> >I don't know about things like stability, linearity or repeatability of
this
> >"device" but that may come with time.
> >
> >Good idea for non-critical tasks I guess.
> >
> >Klaus
> >
> >
> >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/
>
>
>
> Forrest M. Mimms III describes an inexpensive simple pressure sensor, made
> using the black I.C. conductive foam between sections of printed circuit
> board in his "Engineer's Mini-Notebook -- Sensor Projects" booklet sold
> through Radio Shack. See page 27.
>
> Tim
>
>
> Timothy Medema
> CrystaLite, Incorporated
> 3307 Cedar St. (425) 745-6000 800-666-6065
> Everett, WA 98201 Fax: (425) 257-0232
>
> www.crystaliteinc.com
> <mailto:timm@c...>timm@c...
>
>
> The information transmitted is intended only for the person or entity to
> whom it is addressed and may contain confidential and/or privileged
> material. Any review, retransmission, dissemination or other use of, or
> taking of any action in reliance upon, this information by persons or
> entities other than the intended recipient is prohibited. If you received
> this in error, please contact the sender and delete the material from any
> computer.
>
>
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