B&B Electronics 4 Channel Input Buffer Board SDAIBB - Manual (Page 14)

12 SDAIBB1300 Manual
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
Gain Resistor Determination
Replacing a single resistor changes the gain on each buffer.
Change R1 to modify the gain on channel A, R2 to change channel B, R7
to change channel C, and R8 to change channel D. Use Equation 8 to
determine the value of the gain resistor to attain a calculated gain. To use
this gain value, place the gain jumper corresponding to the correct channel
in the User/22.28 position. JP1 corresponds to channel A, JP2 corresponds
to channel B, JP3 corresponds to channel C, and JP4 corresponds to
channel D.
R
G
is the value of the gain resistor in ohms.
Equation 8:
( )
1
100
−
Ω
=
G
k
R
G
Equation 9:
G
R
k
G
Ω
+ = 100
1
Example: Find the appropriate 1% resistor for a maximum gain of 150 and
calculate the actual gain.
From Equation 8: ( ) 141 . 671
1 150
100000 =
−
=
G
R
The nearest 1% resistor that will produce a gain of 150 or less is 681
Ω.
From Equation 9: 8 . 147
681
100000
1
= + =
G
The nearest 1% resistor is 681
Ω
with a resulting gain of 147.8.