PASCO CI-6527A User Manual
Instruction Sheet
for the PASCO
Model CI-6527A
012-08463B
Thermistor Sensor
3.5 mm stereo jack
Thermistor Sensor
BNC jack
DIN
connector
Introduction
The CI-6527A Thermistor Sensor is used for
converting resistance measurements to temperature.
When used with a ScienceWorkshop® interface and
DataStudio software (version 1.8.5 or later), the
sensor allows you to directly measure the temperature
or simultaneously view both resistance and
temperature measurements in one graph.
BNC-to-dual banana plug
cable assembly
insulated
alligator clips
8-pin DIN
connecting
cable
100K thermistor
10K thermistor
3.5 mm stereo plug-todual banana plug cable
Equipment included:
• PASCO CI-6527A Thermistor Sensor
• Cable assembly, BNC-to-dual banana plug
• Cable assembly, 3.5 mm stereo-to-dual banana plug
• 8-pin DIN connecting cable
• Two insulated alligator clip adapters
• Thermistor, 100K ohm
The sensor is a two-thermistor circuit built into one
sensor case. Thermistors are resistors that change
resistance as their temperature changes. One
themistor circuit is used with PASCO 10K thermistors
that have a 3.5 mm male stereo jack.
The other thermistor circuit is 100K ohms and is used
with a BNC jack. The 100K circuit is designed for
use with a 100K thermistor, like that installed in the
PASCO Mechanical Equivalent of Heat Apparatus
(TD-8551A) or the Thermal Expansion Apparatus
(TD-8558A).
The stereo-to-dual banana plug cable is used to
connect the 10K thermister to apparatus requiring two
banana plugs such as the comupter-based Thermal
Expansion Apparatus (TD-8579A).
• Thermistor, 10K ohm
Additional equipment required:
• ScienceWorkshop® Interface
• DataStudio
® Software, version 1.8.5 or later
Applications
• Used with PASCO products that contain built-in
10K and 100K thermistors (i.e. TD-8579, TD8580, etc.)
• Thermal expansion studies
• Mechanical equivalent of heat
• Energy transfer studies
• Thermodynamics
Thermistor Sensor 012-08463B
Thermistor Description
Figure 1 illustrates a typical resistance vs. temperature
curve for a 100K ohm thermistor.
120
100
80
60
40
Temperature( ºC)
20
0
0 100,000 200,000 300,000 400,000
Resistance (ohms)
Thermistors have a negative temperature coefficient.
As the temperature increases, the resistance of the
thermistor decreases. The Steinhart-Hart equation is
used to convert from resistance to temperature, where
T in degrees Celsius is
1
-4
(
8.25x10-4+2.05x10
and R
is the resistance in ohms.
100
.
ln(R100) + 1.14x10
10K thermistor - The 10K thermistor wire plugs into
the 3.5 mm jack and has an output voltage ranging
from 0 to -10 volts. The DataStudio software converts
the voltage to resistance and temperature.
100K thermistor - The 100K thermistor plugs into the
BNC jack and outputs a voltage ranging from 0 to +10
volts. The DataStudio software converts the voltage to
resistance and temperature.
Figure 1
-7
.
ln(R100)
-273.15
3
)
Electronic Circuitry and Internal
Operation
10K Thermistor Circuit - The 10K thermistor circuit
uses a precision voltage source and voltage divider to
determine the thermistor’s resistance. The thermistor
(Rt) is one resistor, and a 13K resistor (R
other in a two-resistor voltage divider network. In the
sensor housing, the reference resistor, voltage
regulator, and filter capacitor comprise the remainder
of the network. The relationship of the 10K
thermistor’s resistance (Rt) to voltage output (V
Rt=-V
out*Rref
where V
/(V
is 10V reference voltage. R
ref
ref-Vout
)
The normalized resistance is R10=Rt/10,000.
The Steinhart equation is used to convert from
resistance to temperature, where T, the temperature in
degrees Celsius is
1
-6
2
.
+ 8.37x10
ln(R10)
(
3.35x10-3+2.56x10
and R
is the normalized resistance of the thermistor
10
-4
.
ln(R10) + 2.38x10
in ohms.
100K Thermistor Circuit - The 100K thermistor
circuit outputs a positive voltage that is directly
proportional to the resistance of the resistor. The range
of resistance over which the sensor functions is 0 to
360K ohms. This resistance range maps into a 0 to 10
VDC output from the sensor. The relationship is Rt =
36,000*V
. The normalized resistance R
out
100,000. The Steinhart-Hart equation is used to
convert from resistance to temperature, where T, the
temperature in degrees Celsius is
1
(
8.25x10-4+2.05x10
-4
.
ln(R100) + 1.14x10
-7
.
ln(R100)
) is the
ref
is 13 Kohms.
ref
-8
3
.
ln(R10)
100=Rt
-273.15
3
)
out
-273.15
)
) is
/
When the Thermistor Sensor is connected to a
ScienceWorkshop interface, DataStudio determines
which thermistor, the 10K or the 100K, is connected to
the unit by the polariy of the V
signal, as long as the
out
thermistors are connected appropriately (10K to the
stereo jack and 100K to the BNC connector).
2
and R
100
in ohms.
is the normalized resistance of the thermistor
®
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