Communications headset tester

[Luciano]

I probed the connector without the headset plugged in and didn't get any power on any of
the pins (well, a few mV, but it was very jumpy, so I figured it was being induced from somewhere).

Did you measure that on the functional station 12 miles away or did
you measure that on the headset tester?

If the station uses an electret microphone then you will have
about 3-9V DC between the microphone line and the microphone GND.


Example of similar circuit:
http://www.tkk.fi/Misc/Electronics/c...tretinput.html

Best regards,

Luciano

EDIT: 3-9V DC with the electret microphone disconnected.
-

[skimask]

Did you measure that on the functional station 12 miles away or did
you measure that on the headset tester?

If the station uses an electret microphone then you will have
about 3-9V DC between the microphone line and the microphone GND.


Example of similar circuit:
http://www.tkk.fi/Misc/Electronics/c...tretinput.html

Best regards,

Luciano

EDIT: 3-9V DC with the electret microphone disconnected.
-

The shop is 12 miles from where they use the headsets. The place where they use the headsets has multiple stations.
The headset tester seemed to be totally dead until I started messing with it
And like I said before, now all I can get is some serious squeal in the headsets when I plug them into it (except when I'm at the extremes with the volume pot that's on the tester).

I'm taking notes on all this good stuff for when I go in next week to beat this project up some more!

EDIT:
I just looked at that epanorama site. I remember looking at that site a few years ago, forgot all about it.
Yes, those diagrams (and others in that site under the audio section) look like they might have something to do with what I'm messing with.
My problem with the tester box circuit might be that I'm treating it totally wrong, possibly treating it like it has a dynamic mike instead of an electret mike, which that little circuit might do the 'conversion'.
I should be 'biasing' one input coming (for lack of a better phrase) from the mike with the battery instead of grounding it, and then sending it off to the + input of the LM386.

I'm going to have a good read of those pages, compare notes, etc. Hopefully this thing will work by noon on monday when I get it re-wired.
JDG