1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Converting phone extension socket to master for PBX extensio

Discussion in 'Alarms, CCTV & Telephones' started by Speakercon, 5 Oct 2014.

  1. Speakercon

    Speakercon

    Joined:
    4 Sep 2011
    Messages:
    76
    Thanks Received:
    2
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    Hi,

    I'm in need of some master phone sockets for use as phone extensions from an analogue PBX.

    I have lots of normal phone sockets, can I convert them to masters by simply adding a 1.8 µF capacitor and 470 kΩ resistor in the way shown in the below diagram using these components?

    Capacitor - http://www.ebay.co.uk/itm/231069607556

    Resistor - http://www.ebay.co.uk/itm/161349300192

    [​IMG]

    Many Thanks
     
  2. Sponsored Links
  3. Lectrician

    Lectrician

    Joined:
    18 Jul 2004
    Messages:
    8,503
    Thanks Received:
    405
    Location:
    Devon
    Country:
    United Kingdom
    Yep, the surge arrestor is not required, known as a PABX master. You will likely get some twits in a bit saying you don't need masters for modern phones. You should still fit masters though, as most standard phones WILL require the ringer.
     
    • Thanks Thanks x 1
  4. Speakercon

    Speakercon

    Joined:
    4 Sep 2011
    Messages:
    76
    Thanks Received:
    2
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    Brilliant thanks! Is the resistor still required?
     
  5. OwainDIYer

    OwainDIYer

    Joined:
    5 May 2010
    Messages:
    4,554
    Thanks Received:
    698
    Location:
    Stirlingshire
    Country:
    United Kingdom
    The resistor is not required on PBX use.

    Its purpose is to provide a circuit even if no phone is plugged in, for line testing.
     
  6. Speakercon

    Speakercon

    Joined:
    4 Sep 2011
    Messages:
    76
    Thanks Received:
    2
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    So would I connect the capacitor from pin 2 too pin 3 on the back of the socket?

    Cheers
     
  7. OwainDIYer

    OwainDIYer

    Joined:
    5 May 2010
    Messages:
    4,554
    Thanks Received:
    698
    Location:
    Stirlingshire
    Country:
    United Kingdom
    yes.
     
    • Thanks Thanks x 1
  8. Sponsored Links
  9. Lectrician

    Lectrician

    Joined:
    18 Jul 2004
    Messages:
    8,503
    Thanks Received:
    405
    Location:
    Devon
    Country:
    United Kingdom
    All PABX master sockets have the resistor and ring cap. Never seen one with just the cap, never tried it without the resistor, but can see it should work.
     
  10. Speakercon

    Speakercon

    Joined:
    4 Sep 2011
    Messages:
    76
    Thanks Received:
    2
    Location:
    Nottinghamshire
    Country:
    United Kingdom
  11. bernardgreen

    bernardgreen

    Joined:
    3 Nov 2006
    Messages:
    25,798
    Thanks Received:
    2,567
    Location:
    Bedfordshire
    Country:
    United Kingdom
    The rated voltage and capacitor are correct, provided the quality is OK they should b OK, the leads are intended for PCB and may have to be extended.

    The resistor may be needed on some PAXs as some modern ones do have line testing functions. But on a PAX unless some of the lines are very long adequate testing can be carried out without the resistor.
     
  12. AlanE

    AlanE

    Joined:
    26 Feb 2004
    Messages:
    2,986
    Thanks Received:
    557
    Location:
    Essex
    Country:
    United Kingdom
    True but it would also provide a discharge path for the capacitor if for example the phone was unplugged whilst phone ringing.
     
  13. Speakercon

    Speakercon

    Joined:
    4 Sep 2011
    Messages:
    76
    Thanks Received:
    2
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    Good point, I'll add the resistor its not much extra work!

    Also I assume + would be too pin 2 and - too pin 3?
     
  14. bernardgreen

    bernardgreen

    Joined:
    3 Nov 2006
    Messages:
    25,798
    Thanks Received:
    2,567
    Location:
    Bedfordshire
    Country:
    United Kingdom
    The capacitor must be a non polarised type as in some circumstances the 50 volt polarity can be reversed.
     
    • Thanks Thanks x 1
  15. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page