PaulSeward.com
Finding his photographic feet, one photo at a time
Etelphone N1900 (was Tele 706 MK1)
Isn’t it a lovely colour! It could do with a bit of a clean, and the mic side of the voice bridge doesn’t seem to work properly (despite me swapping out the mic element) – and various bits of it aren’t original – but it’s interesting for other reasons.
Feel free to wander off if you’re not as into the phone thing as me ;-)
I bought this GPO 706 Phone off ebay, as I’ve been looking for a 706 MK1 for a while and I noticed that this 706 had a metal dial (which appears to be a “Dial No 12“) so stood a good chance of being a MK1, possibly an early one at that.
Taking the lid off shows that it is a MK1 (the MK2 had a PCB) but there’s something odd about it.
See that slot in the middle? It should have a circuit board mounted vertically in it. Not only is the rectifier board missing, so are the middle three contacts. A close look at the socket seems to suggest they were never present. The way the large resistors are mounted seems to reflect that. It doesn’t really match the N806 diagram, although I did notice one thing that’s interesting.
The N Diagram, Page 1, Note F says:
Early issues have dial brown connector connected to gravity switch spring 4 instead of T3
Which this phone does have. It matches Note F and has a Dial No 21 – so I think it probably is an early MK1.
Another clue that it’s probably an early model is that it’s got a paster diagram inside the case. Now, I’m only guessing here because I can’t find any references that would say yes/no on the paster diagram thing but none of the other 706s I’ve seen had them, but they were all MK2s.
The paster diagram is labeled N98293, but I can’t find any reference to an N diagram of that number online, but I assume the paster diagrams are numbered differently. The paster does match the wiring of the phone more closely than N806 does.
So, this is proving to be quite an interesting ebay purchase!
I’m not 100% convinced that the brown handset and the dial surround are original (I think the green 706s had dark green handsets) and it’s possible that this phone is early enough to have originally had a braided handset cord. I suppose that the paster diagram is probably the real key to working out how this phone was originally configured.
Update – 2010-02-12:
I found a number stamped on the baseplate, it says N1900E69 which means that the phone was built by Ericsson, and is an N1900, or “Etelphone” although some of the details still don’t match. So there’s a bit more digging to be done yet!
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BoB Juggling Festival, and when Juggling meets Phones
This is Jon Peat, British Young Juggler Of The Year 2006, probably one of the most interesting ball jugglers I’ve seen in a long time. He was trying out a new routine on stage at the BoB Juggling Festival this weekend. There are some more photos from the show in this album here.
However, the most productive part of the day for me, was my chat to Tarim about my idea for a telephone based siteswap validator.
The Background:
For those that don’t know, siteswap is a mathematical language for describing juggling patterns. The idea is that you can use a string of numbers to represent the pattern. Each number represents a throw event, with the number determining how many beats later the object is thrown again. Eg a 3 means that the object being thrown at that time, is next thrown 3 beats later.
Some strings of numbers are valid juggling patterns, for example 531 (which is a 3 object pattern) but not all strings are valid. For example, 540 is not a valid siteswap, as the 5 object is next thrown in 5 beats time, but the 4 is next thrown in 4 beats time. This means that they’re both thrown by the same hand at the same time. There’s a collision.
There’s a lot more to siteswap than that, if you’re interested in all the gory details start here with this wikipeida article about siteswap.
It’s handy some times to be able to check if a string of digits is a valid juggling pattern or not, telephone dials have digits, so they can be used as an input device. They also have earpieces, so can be used as an output device.
The Plan:
To build a device which you can plug an old rotary dial phone into, which allows you to do the following.
- Pick up handset
- Listen for a dialing tone
- Dial in the siteswap you want to validate
- Hang up handset
- Wait a few seconds
- The phone will then ring
- When you answer the phone, a recorded message plays telling you if the number you dialed is a valid siteswap or not.
I had a firm idea about how to do all those steps apart from step 7, getting a microcontroler to play speech isn’t trivial. Talking to Tarim though gave me an idea of how to get around that though by using a cheap MP3 player. Result!
I’ve built a circuit which interfaces to the phone line, and can detect hook state and count dial pulses. I can get audio onto the phone line. I know *how* to make the phone ring, but am lacking the components to do so.
In short, I’m *soo* close!
Posted in Experiments, Phones, Photos | 2 Comments »
Connecting my Opera 206 to a printer
Hurrah!
It’s only taken me 3 days, but I’ve managed to get my Opera 206 to dump its config out of its RS232 port. It’s designed to be connected to a printer, but I don’t have a printer with a serial port handy so I’ve got it hooked up to my computer instead.
Here’s how you hook it all up:
RS232 (9 Pin DSUB)
|
Opera 206 |
| CTS (Pin 8) |
RTS |
| RX (Pin 2) |
TXD |
| GND (Pin 5) |
GND |
Optional: Connect DSR(Pin 6) and DTR(Pin 4) together on the RS232 plug. (Note, this may be needed for printers, but it seems to work OK without)
Why did that take you 3 days?
Although the above makes perfect logical sense, it’s not what the manual says to do. This is a perfect lesson in “when is it appropriate to trust the manual, and when is it appropriate to think the situation through from first principals”
Just for my reference, here’s the current config of my Opera 206, which looks a lot like the default config:
ispms@super:~$ cu -l /dev/ttyS0 -s 4800
Connected.
Ext Line Number Dialled Duration
Hr Min Sec
--------------------------------------
-----------------------------
Extension Assignment
1 2 3 4 5 6
-----------------------------
Day Service | | | | | |
Line 1 X | | | | |
| | | | | |
Day Service | | | | | |
Line 2 X | | | | |
| | | | | |
Night Service | | | | | |
Line 1 X | | | | |
| | | | | |
Night Service | | | | | |
Line 2 X | | | | |
| | | | | |
Outgoing Assignment | | | | | |
Line 1 X X X X X X
| | | | | |
Outgoing Assignment | | | | | |
Line 2 X X X X X X
| | | | | |
Barring | | | | | |
| | | | | |
Data Protection | | | | | |
------------------------------
Line Programming
1 2
------------------------------
MF : X X
Decadic :
------------------------------
------------------------------
PABX :
Trunk : X X
------------------------------
Ext Line Number Dialled Duration
Hr Min Sec
--------------------------------------
Exception Table
---------------
Ext Line Number Dialled Duration
Hr Min Sec
--------------------------------------
~.
Disconnected.
ispms@super:~$
Oh, and don’t worry – there will be photos of the lunchtime snowball fight along in a minute, I just wanted to write this up before I forget what I did.
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GPO Ring Cadence generation
As I’m sure you all know, British phones ring in the following cadence: “0.4sec on, 0.2 sec off, 0.4sec on, 2sec off” – which is the one true timing for telephone ringing as far as I’m concerned. The USA do some kind of “2 seconds on, 4 seconds off” thing which is easier to generate, but really not very nice to listen to on a lovely GPO phone (My trimphone sounds especially “wrong” with the American cadence)
Anyway, we’ve been scratching our heads about how to make a relay click in the right cadence, to switch the ringing current in the telephone exchange we’re building.
Last week, I sat down with my “Big Book Of 555 Timer Tricks” and sketched out the above circuit – but didn’t have enough of the right component values to build it. Ian did have enough junk components in the right ballpark, so built it at the weekend. And it works! Rah! He’s got video of LEDs flashing and everything!
The circuit uses two 555 timer chips running in Astable configurations, one generating a slow waveform which is used to turn on and off a second timer, which generates a faster waveform. The upshot is that you get short bursts of the faster waveform at the output. The on/off timings are written on the diagram, and are chosen so that you get two “on” pulses from the second timer in the time it takes the first timer to turn on. Bingo, GPO ring cadence FTW!
The interesting(?) bits of this are that the second timer is turned on/off using its reset pin, and that the first timer uses a diode to give a duty cycle of less than 50% – the fun bits are that my phones can now go “rng ring” instead of “ring”
Posted in Experiments, Phones | 6 Comments »
Mystery Component
I’m trying to identify this component from the power supply side of a friends phone exchange (Opera 206). It went bang and let out all its magic smoke when he plugged it in. The photo is from my Opera 206, as his is covered in soot.
It’s connected accross the Live and Neutral on the primary side of the mains transformer. Our initial thoughts were that it was some form of smoothing capacitor, but it’s labeled “VR1″ on the circuit board (which isn’t really a common way to label capacitors) so we’re not sure.
The exchange powers up just fine without it, but as people designing electronics aren’t usually in the habit of including extra components just for fun – we’d quite like to replace it if possible.
The markings say “2754″ and “00|04″ which are a little confusing! So, if you know what this is, and what the markings mean, please let me know in the comments so we can replace it!
Edit: It’s not actually a competition, so I’ve changed the title – the permalink has already been spread around a bit though so it’s staying as-is
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New toy! GEC Alphalink
This is my new toy. It’s a GEC Alphalink, and it’s a telephone exchange (local PABX) – it supports loop disconnect dialing only (none of your modern DTMF nonsense) and contains somewhere in the region of 30 relays. Lets take the lid off…
There are two boards, a main board which has all the control gubbins and connectors for the two incomming exchange lines and the first 4 of the extension lines. There’s a daughter board which hosts the other 4 extension lines. It’s missing a relay, so let’s take it off and give both boards a once over to make sure they look alright and there are no blackened components near the powersupply. (The wiring in my house is a bit suspect, so I like to check second hand stuff by eye before plugging it in!)
Both boards off you can see all the lovely orange relays (these are for connecting lines to the internal voice paths – of which there are two – hence two orange relays per line) The smaller white relays apply the ringing signal to a the line. One of these is missing from the daughter board, and one on the main board is missing it’s lid. I think I know where I can get replacements though.
Lets put it back together and see what it does!
Well, it works, and here it is with a green trimphone on the left and a pulse dialing push-button phone on the right.
All lines (apart from the one with the missing relay) seem to do the right thing. It still doesn’t have the UK ringing cadence so it’s not perfect – but I’m very happy with it! I hooked up one of its exchange lines to my Opera 206 (a smaller, more modern exchange) and that seems to work too.
The next job is to replace the missing and damaged relays, install it, cable up my house, and find myself some way of going from pulse dial->VOIP so I can make internet phonecalls from my phone collection.
Edit: I almost forgot. Mr Stubbs wanted a picture of the wacky “bent wire and hooks” DIP switch arrangement which is used for programming the system. None of your fancy systemphones here thankyouverymuch.
Posted in Phones, Photos | 3 Comments »
Green GPO 746
My new green GPO 746 turned up today.
The line cord on it is the wrong colour for the phone, and is fitted with a Plug 420. The mic element is an electronic Transmitter No. 21A, and there’s a label on the bottom dated 1987. This all makes me think it was a replacement phone issued in the late 80s to a house which already had “Extension Plan 4″ instalation.
I think all it really needs doing to it is a new (green!) line cord, and a new handset cord as the existing one is a bit stretched, then a bit of a clean and it’ll be a fine addition to my growing collection.
I’m also making progress on the plan to build a small intercom/pabx to plug the collection into, they’re more fun if they’re working!
Posted in Phones, Photos | 5 Comments »
Mystery Phone – Identified!
Thanks to the marvelous Sam Hallas – I’ve identified the mystery phone I bought from ebay. It seems to be a “Telefonbau und Normalzeit” (T&N) E2 – so we were right, it is a German design – although it was likely to have been supplied in the UK.
Now that I know what it is, and have a reasonable idea what plastic it is, I can set about taking it apart to clean it up. As you can see from the next picture, it’s quite clearly spent the last 40 years in someones shed!
So, that’s been the sum total of my progress for the weekend.
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