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Rice Lake Z6 Single-Ended Beam, SS Welded-seal, IP67, OIML C3 User Manual

Page 14

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10

Load Cell and Weigh Module Handbook

We have replaced the ammeter with a voltmeter which will
represent the display on our weight indicator. Also, the leads
connected to our indicator are designated +Sig and -Sig.
These represent our positive and negative signal leads. A 10
volt battery represents our indicator’s power supply that
provides the precise voltage to excite or power the load cell.
The resistance values represent our four strain gauges which
make up our load cell.
Since there is no load on our cell, all strain gauge resistances
are the same. Using Ohm’s Law we can figure the voltage
drops at points 1 and 2. Each branch contains 350Ω + 350Ω
= 700Ω of resistance. The current flow in the branch is the
branch voltage divided by the branch resistance.

To figure the voltage at point 1 we can use Ohm’s Law.

Since all resistances are equal, the voltage at point 2 is also 5V.
There is no voltage difference between points 1 and 2 thus a
zero reading is displayed on our indicator.

I

R1 +

R2

= E

R1 + R2

I

R3 +

R4

= E

R3 + R4

R

1

+R

2

R

3

+R

4

=

10V

=

10V

700Ω

700Ω

= 14.3mA

= 14.3mA

E

R3

= I

R3

R

3

= 14.3mA x 350Ω

= 5V

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