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Old 6th Oct 2019, 3:50 pm   #7
Join Date: Oct 2014
Location: West Midlands, UK.
Posts: 1,545
Default Re: Boost the ringer current instead of ...

Originally Posted by Dave Moll View Post
In the days before I had my extensions hung off a PABX, I used a plug-in unit (with a REN of 1) which was presumably the converter referred to above. Its output supported of REN of up to 8, allowing a total of REN of 11 (inluding 3 connected direct to the incoming line).
Dave - the one I referred to was fitted inside a full sized socket, with provision for a 50 supply from a BT SWITCH . Only markings I can find on any of the few I have is DPA/1448/A . 5 TRANSISTORS but no sign of an opto coupler.
Photo attached. The connector is marked (LH, from Top) DCBA and the right hand one 9 from top) 47v , bell( pair) and 0v .No protective diode in the power line, so if volts reversed ,R6 TENDED TO GET HOT. Wired up correctly it had more than enough power to drive an extension bell

Or there's the convertor ringing 2A ,ITEM CODE 375507, normally used with a key system to power an extension bell from extensions ( from memory) set to ring on an incoming call .
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