I tried to make this as thorough as possible. I have a 4p4c socket + cable here. As there is no manual for german wiring I had to measure each wire against each other wire while hearing the "ready to dial" tone to find it out, but I am still clueless.
This is what I got
- 12--0.4V-DC
- 13--4.2V-DC
- 14--0.2V-DC
- 21-0.37V-DC
- 23-0V-AC
- 24-0.1V-DC
- 31-0.4V-DC
- 32-0.001V-DC
- 34-0.2V-DC
- 41-0.2V-DC
- 42-0V-DC
- 43--0.2V-DC
Explaination:
- 1 means white
- 2 green
- 3 yellow
- 4 brown
- First number is one of the colors I put the mass of my oscilloscope to.
- Second number is the color/wire I put the signal of my oscilloscope to.
- one "-" is meant for separation
- Then the value follows
- Then the unit follows
- one "-" is meant for separation
- then there is the type of voltage/current measured
So for instance
43--192mV-DC
means
GND to brown, signal to yellow, result: -192mV, type of voltage/current measured: DC
or
42-5.7mv-AC
means
GND to brown, signal to green, result: 5.7mV, type of voltage/current measured: AC
Please tell me, which cable go to speaker and which to microphone. Also, do I need additional circuitry? In the english wikipedia there is a 500 ohms resistor. Do I need this, what is it for and where to put it?
Answer
UPDATE:
On rereading it's not obvious where you are connecting this or what it is you are connecting.
If this is a headset cord (as it seems to be) then what I said about voltages is wrong.
What are you connecting to what?
OLDER:
Nothing makes sense.
If this is to a "central Office" you should have 50V DC somewhere.
If to a PBX possibly 25 VDC or lower.
1,3 = 4.2V and 3,1 = 395 mV suggests that you are grounding the signal with your scope ground in the second case. You need a differential probe or isolated scope or measurements relative to ground.
Connecting ground to one wire will unbalance a feed circuit and allow induced noise from all over. Balanced load or feed must be used.
Use a magnetic earpiece of around 1000 Ohms or a high impedance one with a say 470 Ohm resistor across it. Connect to 2 wires at a time and listen for dial tone. Go from there.
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