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

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.
Reply to
Chris Turton
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What about a 24VDC to 48VDC converter? I found one at
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model DS25-48 which uses 20~72VDC input & produces 48VDC, 0.5amp (24 watt) and price was $39 each. Check it out.
Reply to
Nam Paik
Post in Possibly there are closer vendors than ones like
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--s falke
Reply to
s falke
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.
Reply to
John Gilmer

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