Difference between revisions of "Chopping Board Scales"

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(Sensors)
(Wires)
Line 47: Line 47:
 
=== Wires ===
 
=== Wires ===
  
Red
+
Red<br>
Black
+
Black<br>
White
+
White<br>
  
White->black=2k
+
White->black=2k<br>
White->Red=1k
+
White->Red=1k<br>
Red->Black=1k
+
Red->Black=1k<br>

Revision as of 00:27, 20 January 2014

Projects
Participants Amx109
Skills
Status Planning
Niche Other
Purpose Fun

purpose: to build a big chopping board with inbuilt scale

Design

  • Waterproof
  • must display weight on surface of chopping board
  • minimum 'maximum weight' of 5kg, with minimum 1g increments. pref 0.1g
  • touch sensitive button
    • on/tare

Electronics

Inspired by http://jdesbonnet.blogspot.co.uk/2010_10_01_archive.html

load cell: http://www.ebay.co.uk/itm/22-lbs-10Kg-Aluminium-Alloy-Hopper-Scale-Load-Cell-Transducer-/290913452703?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item43bbcb029f

Materials

Chopping board:

Sensors

Specification:

Size: 34mmX34mm

Internal 1000 Ohm half-bridge strain gauge load cell, range is 50kg, half-bridge structure.

When measuring, the correct force is applied to the outer side of the strain E-shaped beam portion of the sensor (i.e., a strain gauge affixed to the middle, with a beam of white plastic cover arm) and the outside edges to form a shear force in the opposite direction, i.e., in the middle of strain beam bending necessary changes can occur under stress, strain beam side by another force can not have a barrier.

The sensor use the following three methods:

1, using a sensor with external resistors full bridge measurement range of a sensor range: 50kg. Higher requirements for external resistor

2, the use of only two full-bridge sensors measuring range is the range of the two sensors and: 50kgx2 = 100kg

3, the use of four full-bridge sensors measuring range is the range of four sensors and: 50kgx4 = 200kg


Wires

Red
Black
White

White->black=2k
White->Red=1k
Red->Black=1k