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