Inexpensive load sensor / load cell
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Does anyone know of an inexpensive (hobby/prototype price quality)
load cell in the 25 to 50 pound capacity range?
load cell in the 25 to 50 pound capacity range?
Comments
>Does anyone know of an inexpensive (hobby/prototype price quality)
>load cell in the 25 to 50 pound capacity range?
How about a SPRING used as a coil in a simple L-C oscillator. Just
find a spring that works under your demands (25-50 lbs). Make sure
that under 50 lbs the individual coils do not touch each other.
Solder a wire to each end of the spring and connect it to an L-C
oscillator. (Silver-Solder with a brazing torch works nice for
bonding Steel/Aluminum/Zinc to Copper.)
Circuit Example:
http://home.earthlink.net/~y2kbc/Electronics/BasicStamp/Coilread.gif
Beau Schwabe Mask Designer IV - ATL
National Semiconductor Wired Communications Division
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>bonding Steel/Aluminum/Zinc to Copper.)
You can silver-solder aluminum to copper?
Jay
> >oscillator. (Silver-Solder with a brazing torch works nice for
> >bonding Steel/Aluminum/Zinc to Copper.)
>
>You can silver-solder aluminum to copper?
>
>Jay
Perhaps I'm missing something here, but I "think" this is possible.
...Or perhaps not, please enlighten me.
Beau Schwabe Mask Designer IV - ATL
National Semiconductor Wired Communications Division
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>Perhaps I'm missing something here, but I "think" this is
>possible. ...Or perhaps not, please enlighten me.
I didn't know there was any way to "solder" aluminum to anything.
It's been a few years, but as I recall...
Aluminum can be "welded" (the aluminum itself is melted) to other aluminum
with an oxy gas rig (it's difficult to get the temp correct). Aluminum is
usually welded to other aluminum with special inert gas equipment, but as
far as I know, no soldering -- no way to get aluminum to "stick" to solder.
Does anyone know for certain?
Jay
I have only ever welded aluminum to aluminum. And to do that you need
a MIG (metal-inert gas) welder and a lot off patience. I think it very
unlikely that you would get any sort of robust, electricaly-dependable
connection by brazing copper onto aluminum. If I needed to make an
electrical connection to aluminum, I would drill a small hole in it and
use a brass sheet metal screw to hold the wire to it (aluminum is soft
enough to easily drive a screw into). But all of this is probably
moot, as I have never seen an aluminum spring (the stuff is just too
soft).
Peter
>You can silver-solder aluminum to copper?
>I didn't know there was any way to "solder" aluminum to anything.
There are a number of places selling "solder" to join aluminum and
copper. I've had reasonable success with covering the area to be soldered
on the aluminum with oil, scratching it up with the edge of a sharp knife
and then soldering thru the oil. You can get really good results with
commercial solders meant for joining aluminum to copper. I'm thinking the
lead content of the special solder is either very low or is zero. And the
flux composition is probably a huge contributor. It's been a while so I
can't give you a brand name, but do a search on Google for "solder aluminum
copper" and I bet you get a dozen good hits.
Jim H
>
>I have only ever welded aluminum to aluminum. And to do that you need
>a MIG (metal-inert gas) welder and a lot off patience. I think it very
>unlikely that you would get any sort of robust, electricaly-dependable
Here's $.02 more... You can use an oxy/acetylene torch to weld aluminum
as well, but it has to be *CLEAN*. Aluminum oxydizes quickly; the joint
should be brushe with a stainless steel brush immediately prior to welding
it. It takes practice, mostly because you get no indication that the metal
is about to melt. There is a metalworking video at my local library showing
a guy welding two empty Coke cans together with only a torch and an aluminum
rod.
>can't give you a brand name, but do a search on Google for "solder aluminum
>copper" and I bet you get a dozen good hits.
I found one! I will see how it works...
http://www.solder-it.com/solderitkit.asp
Jay
How about a digital bathroom scale? Anyone dissect one of those yet? I've
got one in my project box (a.k.a. junk pile) at home awaiting its final
fate.
Mike
Original Message
From: fdarnell@c... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=5hadw0sKne5i5RVqaaieVsojBVfRK8WdbjkuXRXx74qZi5IOYQ_HymVk69FmgrIhfWRsLIbhPcS-4nUDxSLc8w]fdarnell@c...[/url
Sent: Saturday, December 01, 2001 8:42 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Inexpensive load sensor / load cell
Does anyone know of an inexpensive (hobby/prototype price quality)
load cell in the 25 to 50 pound capacity range?
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>You mentioned a range but not a resolution so this may or may not work.
>
>How about a digital bathroom scale? Anyone dissect one of those yet? I've
>got one in my project box (a.k.a. junk pile) at home awaiting its final
>fate.
I've peeked, but not dissected. I have an old (working) scale that looks
like a bonded load cell, a PIC microprocessor, and some other obviously
necessary parts like display and voltage regulator. The biggest problem I
see adapting it to use outside its original housing is recreating an
acceptable suspension system that properly applies the load to the
structure containing the bonded load cell.
These systems seem to autozero, but if you ever overload them past the
elastic limit of the part to which the load cell is bonded, it will not
read correctly except at zero. IOW, there was no span or range adjustment
I could see.
Jim H