Mike's PBX Cookbook

Meter Pulse Detectors

At some sites, Meter Pulse Detectors are deployed to aid accurate call costing. The telephone company must provide the correct pulses, either 12 or 16Khz pulses are standard. A price per pulse is required to cost the call, this information being entered in the cost accounting software.

Testing:

To test the meter pulse detectors, connect a volt meter (set to 50 volt DC) to the XT (pulse output) lead of the circuit. Connect the other meter lead to a suitable earth.

When the exchange circuit is free (idle), the meter should read -48 v or -24v. If not, the circuit is faulty.

Make a call on the exchange line. On answer the meter should show a momentary deflection as the Meter Pulse Detector Circuit earths the XT lead in response to the first meter pulse.

While the call is connected, the meter should show regular earth pulses as the Detector circuit responds to the 12/16Khz pulses from the local exchange.

Pin Designations:

CircuitPin No.DescriptionCable Colour
127
2
28
3
29
A-Wire (Tip) Exchange
B-Wire (Ring) Exchange
A-Wire (Tip) PBX
B-Wire (Tip) PBX
XT
White/Orange
Orange/White
White/Green
Green/White
Brown/White
231
6
32
7
33
A-Wire (Tip) Exchange
B-Wire (Ring) Exchange
A-Wire (Tip) PBX
B-Wire (Tip) PBX
XT
Red/Blue
Blue/Red
Red/Orange
Orange/Red
Green/Red
335
10
36
11
37
A-Wire (Tip) Exchange
B-Wire (Ring) Exchange
A-Wire (Tip) PBX
B-Wire (Tip) PBX
XT
Red/Slate
Slate/Red
Black/Blue
Blue/Back
Orange/Black
439
14
40
15
41
A-Wire (Tip) Exchange
B-Wire (Ring) Exchange
A-Wire (Tip) PBX
B-Wire (Tip) PBX
XT
Black/Brown
Brown/Black
Black/Slate
Slate/Black
Blue/Yellow
543
18
44
19
45
A-Wire (Tip) Exchange
B-Wire (Ring) Exchange
A-Wire (Tip) PBX
B-Wire (Tip) PBX
XT
Yellow/Green
Green/Yellow
Yellow/Brown
Brown/Yellow
Slate/Yellow
647
22
48
23
49
A-Wire (Tip) Exchange
B-Wire (Ring) Exchange
A-Wire (Tip) PBX
B-Wire (Tip) PBX
XT
Violet/Orange
Orange/Violet
Violet/Green
Green/Violet
Brown/Violet
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