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4
C
1
The sensitivities increase in 10% increments. The SPAN
POT range is ±10% which should cover the entire sensitivity
range from 0.5 to 4.0 mV/V. Two extra through-hole resistor
locations R4, R5 and one surface mount resistor, R7 are
available for covering any sensitivity value not covered by
resistors in the tables above. (See Figure 4.1).
2
The required through hole resistor value can be
calculated by using the following formulas:
R-gain (Gain setting resistor) = 60,000/(Gain-4) where
Gain (Design gain) = V-out/(V-sensitivity x V-excitation)
Units are in Volts and Ohms.
3
The formulas above will give you the correct output when
the SPAN POT is connected to the circuit. With the SPAN
POT in the circuit, it will give you twice the desired output.
Therefore V-out equal to half the required output should
be used. Examples are shown below:
Example:
4
For SPAN POT to be connected and the output
adjustable, solder switch "A" needs to be Open.
5
R4, R5 can be any through-hole resistor value as
required.
R7 can be any surface mount resistor value as required.
14
ALIBRATION
V-out = 100 mV (a V-out of 100mV will give
you an actual output of 200mV) (1999
counts on the LCD Display)
V-sensitivity = 3 mV/V
V-excitation = 1.24 Volts
Gain = 100 mV/(3 mV/V x 1.24) = 26.9
R-gain = 60,000/(26.9-4) = 2.62 K Ohms
& G
S
AIN
ELECTION
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