ACR Electronics SmartReader Plus Reference Manual page 65

power rating greater or equal to 0.1 watts. Therefore, a quarter watt resistor will do fine.
You can also modify the 200mV channel to log current loop signals with greater sensitivity than
the two 25 mA channels. Put a 100 ohm resistor across the "200mV" and "Common"
terminals and you will be able to log currents from 0 to 2.0mA with approximately ten times the
resolution of the 25mA channels. The equation to use to determine the other current (Iin)
ranges, in milliamps, is:
Resistors
Resistors that can be used with the SmartReader Plus 7 are readily available at most
electronic parts supply stores. Ask for precision 1% metal film resistors with a temperature
coefficient of less than 500ppm. The most common ones are quite small and made in the
form of a cylinder with axial leads. To show the value of the resistor, either there is:
· a color code painted on each resistor in the form of bands
· a number (followed by a letter) stamped on them
For resistors with a tolerance of 2% or looser, there are four bands or three number digits
while the resistors that are 1% or better have five rings or four number digits. In the case of
1% values the first three digits or rings correspond to the resistors value and the fourth digit or
band is the number of zeros to be added. The fifth band or letter indicates the manufacturer's
tolerance of the resistor. For example, a 30,900 ohms resistor would be shown as orange,
black, white, red, black or "3092F".
Copyright © 2010 ACR Systems Inc. All Rights Reserved.
Figure 7-5: Modified 25mA Channel
R = 200 / I
Color Number
Black 0
Brown 1
Red 2
SmartReader Plus Data Logger
in
Tolerance Letter
1% F
2% G
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