A&D AD-4405 User Manual
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.
using one load cell.
A
D
B
E
*
*
25
.
0
£
Weighing instrument
using multi-load cell
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
B: Rated output [mV/V]
D: Weighing interval [kg]
E: Excitation voltage [mV]
N: Number of load cells
Verification Example
Design:
Load cell
Load cell
N=1
Rated capacity
A=750 [kg]
Rated
output
B=3
[mV/V]
Excitation voltage E=5000 [mV]
Weighing interval
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.
design.
3. Installation and Precautions