LoadCell (기본자료)

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http://www.tinkerforge.com/en/doc/Hardware/Bricklets/Load_Cell.html

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http://www.phidgets.com/docs/Load_Cell_Primer

Single-Point Load Cells

This Single Point Load Cell is used in small jewelry scales and kitchen scales. 

It’s mounted by bolting down the end of the load cell where the wires are attached, and applying force on the other end in the direction of the arrow.

Wires가 연결된곳을 bolting down하고, 그 반대쪽에 화살표 방향으로 힘을 가한다.

Where the force is applied is not critical, 

as this load cell measures a shearing effect on the beam, not the bending of the beam. 

If you mount a small platform on the load cell, as would be done in a small scale, this load cell provides accurate readings regardless of the position of the load on the platform.

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https://learn.sparkfun.com/tutorials/getting-started-with-load-cells

Getting Started with Load Cells

Have you ever wanted to know the weight of something?

How about knowing the change in weight over time?

변화를 알아내는건 어떨까 ?

Do you want your project to sense the presence of something by measuring strain or a load on some surface.

If so, you’re in the right place.

This tutorial is here to help you get started in the world of load cells and their variants.

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Load Cell Basics

Types of Load Cells

A load cell is a physical element (or transducer if you want to be technical) that can translate pressure (force) into an electrical signal.

So what does that mean? There are three main ways a load cell can translate an applied force into a measurable reading.

Hydraulic Load Cells

Hydraulic load cells use a conventional piston and cylinder arrangement to convey a change in pressure by the movement of the piston and a diaphragm arrangement which produces a change in the pressure on a Bourdon tube connected with the load cells.

▲Pneumatic Load Cell에 의해 W를 적용하면 Nozzle과 Supply사이의 공기압이 Pressure Gauge로 빠져나간다.

이는 Load Cell의 원리와 유사하다.

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http://www.utilcell.com/en/content/load-cell-electrical-circuit

Wheatstone Bridge

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http://www.devicemart.co.kr/1160242# 디바이스마트 로드셀 기준으로 데이터시트 분석 Capacity: 50KG (견딜 수 있는 load의 크기) Rated output(MV/V): 2.0±0.15 Accuracy class: C2 Maximum number of load cell verification intervals(N max): 2000 (2000개의 interval을 두고 감지가능) Minimum number of load cell verification intervals(Vmin): EMax/5000 Combined erro(%RO): <±0.030 Creep(%RO/30min): 0.03 Temperature effect on sensitivity(%RO/°C): 0.0016 Temperature effect on zero(%RO/°C): 0.003 Zero balance(%RO): 1.0 Input resistance(Ω): 402±6 Output resistance(Ω): 350±3 Insulation resistance(MΩ<50V>): 5000 Recommended excitation voltage(V): 10~15 (권고하는 Excitation Voltage) Compensated temperature range(°C): -10~+40 Operating temperature range(°C): -35~+80 Safe overload(%RO): 150 Ultimate overload(%RO): 200 Load cell material: Aluminium Plafform size: 350x350mm Connecting cable: ø4.2x350mm Method of connecting wire: Red(+),Black(-),Green(+),White(-) Connecting Method에 따라서 East Coast Color Code와 West Coast Color Code로 나뉜다. NT114990100 의 경우는 West Coast Color Code에 해당한다. 여기에 따라 Amplifier에 연결 방식이 미묘하게 다르니 유의하자. ▼East Coast Code  Color  Function  Green  +Excitation  Black  -Excitation  White  +Signal  Red  -Signal http://electronics.stackexchange.com/questions/18669/how-to-wire-up-a-3-wire-load-cell-strain-gauge-and-an-amplifier I'm trying to wire it up to my Arduino to detect changes in weight. From what I understand,  the changes in voltage  are so small that the Arduino can't detect the changes without amplifying the voltage.  So I bought an 8-pin LM741CN Op-Amp at Radio Shack that looks something this: I found this video that shows how to wire everything up. However, I can't figure out the schematic and why they are using two load sensors  instead of just one.  난 can't 이해할 수 없다. the 회로를 and 왜 그것들이 사용하는지 두개 로드센서들을 instead of just one대신에. They also mention resistors but I'm not sure why they are using them (and why the sizes they chose), or where in the circuit to put them.

Can someone please help me figure out how to wire this thing up to detect changes in voltage? 

도와줄 누군가 있나? 날 이해하게끔 how to wire연결하는 이걸 up to 감지하기위해 변화들을 in 전압에있어서

Also, is there a way to do this by using only one of these sensors? 

This is what I've done so far:

또한, 방법이 있는가 to do 이걸하는 by 사용함으로써 하나의 센서를

이게 what이다. 내가 여태껏 해온.

The amp also has some pins that I don't understand: Offset null, NC. What are these pins for? Should I be using them?

Update: Now I am working with an Instrumentation Amplifier (AD623). 

I also now have a 4-wire load sensor that I am playing with. 

Still can't get it to work, 

but I thought I would try to understand that before moving to the 3-wire load sensor.

▼차동증폭기

▼차동증폭기 계산식

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http://www.vctec.co.kr/product/detail.html?product_no=8020&cate_no=145

http://www.devicemart.co.kr/1137922

http://www.11st.co.kr/product/SellerProductDetail.tmall?method=getSellerProductDetail&prdNo=1246529800&trTypeCd=78

http://www.vctec.co.kr/product/detail.html?product_no=10375&cate_no=65

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