lol.

I suppose a fluid link is pretty useful (except on Skaro).

Thanks once again Nik for your assistance.

My pal tells me that stromberg-carlson is an american phone,and he has no direct experience of it.HOWEVER-things should be basically the same inside.Firstly you must identify the ringer coils(should be just above the bell)These should have a wire in either side leading to connectors.Remove the right hand wire from the connector,and connect your relay apparatus between it and the connector.
Clear as mud? i'll do some diagrams if u need!

Thanks again Nick.

Do you happen to know what voltage the ringer coil works on (so I can get correct solenoid), I've heard 50v!

The ringer is activated by a pulse from the telephone line,so it should be a very low voltage,most electronics stuff that i work with seems to run on 5v.for safetys sake(although its not much of an issue on this side of the workings) id get it checked out with a voltmeter

Quote from: bignick board=faq thread=1119182488 post=1122545142The ringer is activated by a pulse from the telephone line,so it should be a very low voltage,most electronics stuff that i work with seems to run on 5v.for safetys sake(although its not much of an issue on this side of the workings) id get it checked out with a voltmeter

Actually, there are two voltages involved.  The normal line or "Tip" voltage is on the order of 6 volts DC (US phones - UK are a bit different, but only by a volt or two plus or minus so the 5V sounds about right) - this is what is normally live on the line that allows the telephone exchange to tell when the receiver is lifted and is also the carrier voltage for the signal.  However, there is also an AC "Ring" voltage the exchange sends to signal an incoming call - this is because on old style phones with a mechanical ringer they required much higher AC voltage for the coils in the ringers to work (around 60 volts AC for the US - but I think the 50 VAC is correct for UK). 

That's why a phone line is perfectly safe to work on while live AS LONG AS nobody is ringing in at the time.  If some one does, you can get quite a nasty surprise.

Do note that you should NEVER connect a telephone ringer to wall outlet voltage as it will well and truly fry it (and possibly you in the bargain). 

Presumably this means that in the UK, where the telephones ring with a double ring nowadays (I think it was different before the war), the lamp will flash with a double flash in a most un-Tardis-like way.

(But there may be no way round this, and to have the lamp flash at all would be an achievement.)

Been wondering about the double ring thing for a while, maybe if I ask BT nicely they'll change it back!

Saying that, the Crich lamp flashed ok. Perhaps this is because they use a switchboard?

Ah, it's been awhile, so some of my info was hazy.

Forgot that actually, though the line voltage under load is in the 6 VDC range, that without a load it is nominally 48 VDC (US) or 50 VDC (UK). 

Also had remembered approximate load voltage for the ringer, in that it can range from 40 VAC as high as 150 VAC at from 20hz-40hz depending on vintage and country when measured without a load (so yes, in theory you could connect to a house's AC mains to test the ringer, but this is something you should never do, as the mains are bloody dangerous!).

Best site I've ever come across for this sort of stuff is "Bobs Telephone File".

Homepage is at:
http://web.ukonline.co.uk/freshwater/homepage.htm

Menu of pages with general info on how things work here:
http://web.ukonline.co.uk/freshwater/menuhow.htm

Including REALLY useful "How Telephones Work" page on both US and UK telephone system - direct link here:
http://web.ukonline.co.uk/freshwater/howtele.htm

And best of all, he has rather extensive info on the UK Police telephone system, including quite a few specifics (more for the earlier Posts, unfortunately, than the later Post and/or Box ones).

General menu for pages with info on the Police System is here:
http://web.ukonline.co.uk/freshwater/menupa.htm

First link there is of particular interest as it leads to a sub-menu on the Ericsson hardware (including phone model specifics) used in the Police System - direct link:
http://web.ukonline.co.uk/freshwater/ericsson/menupol.htm

Days and days worth of info to sort through on the site, much of it quite relevant and useful, including things like schematics of various phones, etc.

Not a lot on the signaling system hardware in the Police Boxes and Posts, but some.

Bob's site is excellent although everytime I go to it, I end up finding something else 'new' that I'd missed the time before.

On the flip side, I also manage to 'lose' things I found the last time I visited.

I've found something that may (if I'm reading the blurb correctly) be useful for making the lamp flash. It's called a 'Ring Detector' and it costs 52 quid and it 'will drive mains powered sounders or beacons in response to normal ringing signal'.

There's also a 'Ring Detector Visual' for £30 which - guess what - 'emits high-intensity flash on incoming calls'!

They're made by a company called Comtec ( http://asp2.miuk.com/comtec ) and the products are here: http://asp2.miuk.com/comtec/documents/telephone%20&%20cabling%20accessories.pdf

Googling 'ring detector' gets lots of useful stuff... including how to build one, if you're brave enough.

the ringer on a standard uk telephone operates at 70 to 90v AC at 25 Hz