A&D Weighing Indicator AD-4405 - Manual (Page 8)

Page 6 AD-4405 Weighing Indicator
3.1.3. Adjustment of the Load Cell Output
Caution Use a metal film resistor in the range of 50kohm to 500kohm with a
good temperature coefficient, when adding a resistor to adjust a load
cell output. Use as large of a resistance value as possible in the range
in which the zero adjustment is possible. Solder this resistor at a point
near the load cell or the indicator.
In Case of Reducing the Output Voltage
When the zero output is too large, add a resistor
between EXC+ and SIG-.
In Case of Adding an Offset Voltage to the Output
When the zero output is too small, add a resistor
between EXC+ and SIG+.
3.1.4. Verifying Load Cell Output and Input Sensitivity
The input sensitivity of the indicator is 0.25
mV /division or more. Adapt to the following
inequality, when you design a weighing instrument using the indicator and load
cell(s).
Caution A change in input voltage sensitivity is required to cause a one division
change of the display. Select as large an input sensitivity voltage as
possible so that the weighing interval becomes stable.
Consider the leverage if a lever is used.
Weighing instrument
using one load cell.
A
D B E
* *
25 . 0 £
Weighing instrument
using multi-load cell
N A
D B E
*
* *
25 . 0 £
A: Rated capacity of load cell [kg]
B: Rated output [mV/V]
D: Weighing interval [kg]
E: Excitation voltage [mV]
N: Number of load cells
Verification Example
Design:
Load cell
N=1
Rated capacity A=750 [kg]
Rated output B=3 [mV/V]
Excitation voltage E=5000 [mV]
Weighing interval
D=0.05 [kg]
Weighing capacity 300 [kg]
25 . 0 1
750
05 . 0 3 5000
* *
³ =
. Therefore,
regard the instrument as a good
design.
3. Installation and Precautions