Connect with us

Telephone line adaptor (-24v to -48V)

Discussion in 'Electrical Engineering' started by Chris Turton, Sep 10, 2003.

Scroll to continue with content
  1. Chris Turton

    Chris Turton Guest

    Hi all,

    I am in the need for a telephone line adaptor that will convert a -24v
    analogue PABX extension into -48V for connection to the telco network so
    that the extension can be driven through an Off Premise Extension circuit
    (OPX) extension in the exchange. The current -24V circuit does not have
    enough grunt to drive through the exchange to the remote location.

    I have found a product at proctor & associates in Washington, but this seems
    to be the only one on the planet as far as I can tell.

    Anyone else have an idea?


    Chris Turton
    Sydney, Australia.
  2. John Gilmer

    John Gilmer Guest

    It all depends upon the signaling details.

    If your PBX machine just uses loop signaling for the extension, and the
    remote telephone gets its talk battery from the PBX you don't need to do
    anything. If you need 48 volts just to extend the talk/signaling range
    you just put a 24 supply in series with the PBX battery at the line circuit
    of the extension. (I have seen this approached used in telco offices where
    a remote customer ended up with a 70 volt battery!

    I strongly suspect that the telephone network doesn't really care whether
    you have a 24 or a 48 volt battery: when it detects the remote extension is
    off hook it will send off hook to your machine. And if it detects ringing
    it will pass that on.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day