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OPERATION
The C7089 Outdoor Sensor converts outdoor ambient
temperature to a resistance that the W8900 Remote
Module can interpret. The W8900 Remote Module in turn
3900
3800
3700
3600
1
3500
3400
3300
3200
3100
3000
2900
2800
-40
-20
0
(-40)
(-29)
(-18)
1
RESISTANCE INCREASES 4.84 OHMS PER 1°F CHANGE OR 8.7 OHMS PER 1°C CHANGE.
M6358
Fig. 3. C7089A sensor resistance vs. temperature performance characteristics.
20
40
60
80
(-7)
(5)
(16)
(27)
TEMPERATURE
sends a signal to the PC8900 where the outdoor tempera-
ture is displayed when the CHECK key is pressed. The
C7089 has a positive temperature coefficient (PTC), which
means that the resistance increases as the temperature
increases. Fig. 3 shows the resistance characteristics of
the C7089 Sensor.
100
120
140
160
°F
(60)
(79)
(38)
(49)
(°C )
3
C7089 OUTDOOR SENSOR
OUTDOOR TEMPERATURE
OHMS OF
RESISTANCE
°F
°C
-40
-40.0
2929 to 2905
-35
-37.2
2953 to 2929
-30
-34.4
2978 to 2953
-31.7
3002 to 2978
-25
-20
-28.9
3026 to 3002
-15
-26.1
3050 to 3026
3074 to 3050
-10
-23.3
-5
-20.6
3099 to 3074
0
-17.8
3123 to 3099
5
-15.0
3147 to 3123
-12.2
3171 to 3147
10
15
-9.4
3195 to 3171
20
-6.7
3220 to 3195
3244 to 3220
25
-3.9
30
-1.1
3268 to 3244
35
1.7
3292 to 3268
40
4.4
3316 to 3292
7.2
3341 to 3316
45
50
10.0
3365 to 3341
55
12.8
3389 to 3365
3413 to 3389
60
15.6
65
18.3
3437 to 3413
70
21.1
3462 to 3437
75
23.9
3486 to 3462
26.7
3510 to 3486
80
85
29.4
3534 to 3510
90
32.2
3558 to 3534
3583 to 3558
95
35.0
100
37.8
3607 to 3582
105
40.6
3631 to 3607
110
43.3
3655 to 3631
46.1
3679 to 3655
115
120
48.9
3703 to 3679
120
51.7
3728 to 3703
3752 to 3728
130
54.4
135
57.2
3776 to 3752
140
60.0
3800 to 3776
145
62.8
3824 to 3800
65.6
3849 to 3824
150
69-0896—1
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