Author Topic: I have an PABX with 48V 50Hz rining current .. how to change??  (Read 133 times)

Offline dsk

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I have an PABX with 48V 50Hz rining current .. how to change??
« on: October 20, 2021, 05:03:45 AM »
I do not actually need my Erifox II but it understands both rotary and DTMF.  Could I just do like this  on each line?  (one common 25Hz power source)

dsk

Offline RB

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Re: I have an PABX with 48V 50Hz rining current .. how to change??
« Reply #1 on: October 20, 2021, 03:14:44 PM »
Hi DSK.
Have not heard much from you lately...
Hope all is well with you and yours.
I do not know that circuit, but...
Since you are completely bypassing the pbx ring source, depending on what you have plugged into the line, it looks acceptable???
It looks like your pbx is converting an AC signal to a 1/4 DC signal???
But still allowing the AC to go around the diode???

Offline dsk

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Re: I have an PABX with 48V 50Hz rining current .. how to change??
« Reply #2 on: October 21, 2021, 01:45:22 AM »
The diode will reduce the ringing current even with the cap across, and voice will work well, the cheap Ericsson solution just puts out 48V at network frequency  (here we have 50 Hz) and that rings not well on ringers with gongs.   The diode is for as much as possible block ringing current, but the capacitor reduce that effect in hence to not lower the voice signal, maybe the cap. is not needed?
(And yes low activity from me during the last 1/2 year, changed job and its fun, but lots to do. I have been a teacher for 20 years, and now I am kinda janitor + teacher in a new school in a 100 years old building. (Same pay)  My old headmaster and I could not agree in whats safe fire protection, and when I asked the fire-dept. and they said I was right..... I got this job with a great headmaster that wanted a safe school.  :)   )

dsk
« Last Edit: October 21, 2021, 01:51:16 AM by dsk »

Offline RB

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Re: I have an PABX with 48V 50Hz rining current .. how to change??
« Reply #3 on: October 21, 2021, 09:03:02 AM »
Congrats on the new job! same pay, plus FUN, is a win.
It is surprising how people in power can have a serious shortage of common sense.
The decisions they adhere to confound logic, and frustrate those of us who can see the problems they cause.
Safe, plus fun = happy. 3 things we look for more and more as we age.

The cap you refer to in your circuit, may indeed not do much, as the voice is not needed during ringing...???...
But may be needed after ringing, as voice is fluctuating, and the diode would hinder that. I believe.???
Bypassing as you suggested, leaves more options for creativity.
I personally find myself frequently needing to find ways around cheesy design methods.
You, my wise friend, have a creative mind. I am sure you will soon find a solution for your project.
I hope someone here can offer better advice?
Posting on the OTHER sight, may be more productive. Regards!

Offline dsk

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Re: I have an PABX with 48V 50Hz rining current .. how to change??
« Reply #4 on: October 22, 2021, 11:47:11 AM »
Maybe that capacitor is not needed for the speech circuit, at this 1967 all the voice signals just travel trough the bridge rectifier. http://www.classicrotaryphones.com/forum/index.php?topic=13118.msg137870#msg137870

dsk