I've just moved my master socket and replaced it with a new one. Two wires come into the house and (per the POTS info on diyha.co.uk) i connected these to terminals 2 and 5 in the back of the socket. phone and net now working fine.
However, the house has, on the wall in the hallway, a very nice old bell ringer. This used to work and made a hell of a racket. Really nice - no missed calls from buried DECT handsets.
However, i cant work out how to connect this. It used to work but in the course of various DIY projects it was disconnected and i've mislaid my wiring notes. it has two wires connected to it - where do i connect these?
The old master socket had an internal connection block for a wired extension but this one doesnt. i tried connecting directly across 2 and 5 but that just made the line busy. So what next?
Your master socket will (or *should*) have a ringer capacitor, connected between 2 and 3. The bell needs to be connected between 3 and 5. If it's an old style 1000 ohm bell which has never been modified, you'll need to wire a
3000 ohm resistor in series with it - otherwise it will load the line too much, and stop any other bells from ringing.
What type of master socket is it? On the usual NTE5 sockets, the incoming pair needs to be connected to A and B. The 2, 3, 4 and 5 connections are for extension wiring.
You are of course aware that BT will get upset if they discover that you've been mucking about with your master socket - other than connecting extension wiring to the removeable faceplate?
What type of bell is it? If it's in a rectangular(ish) box there should be a capacitor wired in series with the bell coils (if you have the right terminals). If the capacitor is there, simply connect the terminals across 2 & 5 of the line. You should also put a resistor of about 3kohms in series, to avoid shunting other ringers too much. If there isn't a capacitor you'll have to provide one - about 2 microfarads is correct.
There can't be a cap in there - it was wired to the extension front plate of the bt master socket before. There was never a problem with the other ringers - all that's connected is a DECT base station and an ADSL router.
There might well be a cap in the bell. There are basically two ways of putting an old bell ringer into a new circuit: with the cap, across 2&5, or without the cap, across 3&5. Either way the solenoids should be replaced with 2k ones or a 3.3k resistor put in series.
Also, make sure the coils are in series (they will have been in parallel for operation with wired-in or jack-plug phones). (I rather suspect the resistor might not be required once they are in series.)
Not usually. The old telephone bells used two 500 ohm coils in series, whereas the newer ones use(d) two 2000 ohm ones (again in series). Paralleled bell coils were _very_ rarely used - only, I believe, on some private circuits.
I'm not clear why i need to mess about adding resistors and capacitors to the bell. it worked with my current phones until i moved/replaced my master socket. Anyway, i've already disposed of the old BT master but i've ordered a BT equivalent with AB terminals for the input and 'post-cap' extension connections. that should sort it out. i'll just have to hope i don't need to call BT out in the next few years.
With the old hard wired system that this came from, the bells were wired in series. Hence you had to alter internal connections on the phones.
Modern plug in phones have the bells in parallel. And therefore have high impedance ringers. So if you wish to use an old low impedance bell you have to make it 'look' more like a modern sounder.
It wasn't clear from your original post how old the bell was, or when it was last connected to the system.
In days of yore - before modular sockets were used for phones, and everything was hard wired - the bells in multiple phones were wired in series. Each bell had a nominal impedance of 1000 ohms. When the changeover to modular sockets took place, bells were then wired in parallel - and needed to be 4000 ohms - otherwise they loaded the circuit too much, and failed to ring. So, it is only if you have an old 1000 ohm bell which has never been modified that you need to put a 3k resistor in series with it.
You won't need a capacitor if you connect the bell between 3 and 5 of the master socket because the required capacitor is inside the master - but you
*will* need one if you connect it straight across the incoming pair (equivalent to being between 2 and 5 in the master socket).
You don't. A few years ago you might have found some advantage to it.
The telephone line can deliever "4 REN" of bell ringing power. A recent (4000 ohm) bell is 1 REN, an old (1000 ohm) bell is 4 REN. A modern squeaker is a tiny fraction of this load. If you have more than 4 REN, it's possible that some ringers (usually the 1000 ohm bells) will start to work inadequately. It's not a hard limit though - you can usually get to about 6 before things go squiffy.
To avoid over-loading the bell-power with an old bell, then first of all try it. If you have just one old bell and modern squeakers, then chances are it will work fine. If you get trouble, then put a 1000 ohm (approx) resistor in series with the old bell. This now only uses 2 REN of bell power, leaving plenty in reserve for the other bells. if you put 3000 ohms in series with it, that's limiting the power to the old bell a bit and it might itself start to ring feebly.
If you have an old 746 phone (last of the commonplace grey plastics) then you can replace its internal 1000 ohm bells with an '80s vintage BT-issue 4000 ohm bellset - parts are on eBay regularly. With some engineering you can do this to old bakelite phones too.
You can also try adjusting the gongs. These are drilled off-centre and by slackening the central bolt and rotating them you can adjust for best ring on that particularl power and circuit. Nutlock them afterwards, otherwise they tend to work loose again and make a horrid rattle when ringing.
If you want your house to sound like the Hunchback's Ball at Notre Dame, then get a local ringer - a relay with a power supply. Alternatively browse eBay for old BT-issue external bells with their own power supply.
REN was never applied to series wired bells - it only came in at the start of the '80s with "New Plan" sockets and paralleled bells with a single capacitor.
No, but you can usually get 6 4000 ohm bells to ring in parallel when the spec only guarantees 4. I've heard up to 3 1000 ohm bells ringing together, but not loudly.
BT guaranteed as many bells working as they'd offered to rent to you. If they didn't work from th eline itself, they'd fit an elephant grey box (can't remember the name) containing a relay and a transformer. This would be a freebie, you just had to supply mains power to it.
OTOH, an extension bell at GPO prices was roughly equivalent to my entire phone bill.
On Fri, 02 Dec 2005 20:27:56 +0000,it is alleged that Owain spake thusly in uk.d-i-y:
I used these devices on a PBX (Which only *had* a REN of 1 on the ext. ports) to run 746s, worked a treat. The provision is that the downstream devices _must_ use the pin 4 ringing wire. If they use 2+5 like many modern DECT phones, they load the exchange rather than the ringing converter. In this case of course, the OP could choose to connect to the correct wires for this to happen.
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