Sunday, July 06, 2008


BT i-Plate filter

Samknows reports the introduction of BT's Patent Pending iPlate. This is another take on filtering of the bell wire and works by interposing a plate between the master socket wall plate and detachable faceplate. On this plate is a circuit board which provides a 22 mH choke in series with the bell wire to minimise interference pickup from both wired and plugin extensions.

The iPlate is intended for end user fitting using only a screwdriver, without disconnecting and reconnecting wires. The iPlate plugs into the wall plate and the faceplate into the iPate, the extension wires on the faceplate are passed through a slot in the bottom of the iPlate to save the effort of remaking the connections.

In addition to the series choke on the bell wire both of the signal lines 2 and 5 pass through another twin coil device with a ferrite (?) core. Here's a photo of the device:

The coil device looks like a transformer (to a relative layman) however the DC continuity of both signal lines is maintained so it appears to inductively couple the two lines while at the same time inserting a 4.6 mH inductance into each. The device is marked B302H.

Here are some more general shots of the iPlate

The iPlate is intended for a specific set of ADSL users - those who don't want to get involved in wiring changes and who have a BT NTE5 master socket with a T Telecom or BT Piper logo. The new Openreach logo NTE5 plates (as shown in the photo) already have the bellwire choke built in. Non-NTE5 faceaplates can't accept the iPlate.

An iPlate is probably best suited to users who want to use ADSL on an extension, as it will minimise the impact of extension wiring. It does not replace the microfilters you need on each phone / fax / Sky box.

If you can use the Broadband adjacent to the NTE5 master socket then a full filtered faceplate is a better choice as it removes the need for microfilters and removes the ADSL signal from the extension wiring.

If you have a DIY bent then simply removing the ring / bell wire from terminal 3 of your master socket will achieve what the iPlate sets out to do - isolate the ring wire as a source of interference.

Here's a simple circuit diagram of the iPlate internals :-

If anyone can offer an explanation of the function of the twin coil device please post a comment below. Thanks.



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