Model 109SS Temperature Probe

1: Excite-Delay (SE) (P4)

1:

1

Reps

2:

25

2500 mV 60 Hz Rejection Range (Delay must be zero)

3:

1

SE Channel

4:

1

Excite all reps w/Exchan 1

5:

2

Delay (0.01 sec units)

6:

2500

mV Excitation

7:

3

Loc [V_Vx ]

8:

.0004

Multiplier

9:

0.0

Offset

6. Measurement Details

Understanding the details in this section are not necessary for general operation of the 109SS Probe with CSI's dataloggers.

The Therm109 Instruction outputs a 2500 mV excitation and measures the voltage across the 24.9 K resistor (Figure 6-1). The thermistor resistance changes with temperature.

EX BLACK

10K3AI

THERMISTOR

HI RED

24.9K Ω, 0.1%

AG PURPLE

G CLEAR

FIGURE 6-1. 109SS Thermistor Probe Schematic

The measured voltage, V, is:

=24,900

V VEX 24,900 + Rt

Where VEX is the excitation voltage, 24,900 ohms is the resistance of the fixed resistor and Rt is the resistance of the thermistor

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