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#142994 - 04/21/05 04:31 AM Another old telephone
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Just to add to the telephone threads here.
Here are a few pictures of a type of telephone that was very popular at one time here in NZ.
These phones were the only choice you had for a telephone, between the late 60's and the mid 80's (unless, of course, you had something older):



They came in a rather conservative range of colours, I've only ever seen this particular colour, a red one and a green one, however I have an idea there was also a black model too.
Here is it's pedigree:



I had no idea that these things were actually made in NZ.
These things were hardwired into the wall, via a connector like this:



And under that cover:

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#142995 - 04/21/05 04:42 AM Re: Another old telephone
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Now, inside the actual phone itself.
Here's a view of the terminal block and componentry:



The ringer coil:



And the back of the dial mechanism:



Paul,
In this picture below (which is a closer picture of the circuit board, there appears to be 2 devices next to that green capacitor(?), in a black plastic cover, they look like neons, are they in fact neons?.
If they are, what are they doing in a domestic telephone?
How come I've never seen the telephone light up?.




Sorry my telephone didn't come with a circuit diagram.
This was a sign of things to come.

[This message has been edited by Trumpy (edited 04-21-2005).]
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#142996 - 04/21/05 12:02 PM Re: Another old telephone
geoff in UK Online   content
Member

Registered: 12/30/02
Posts: 172
Loc: UK
That looks VERY much like the UK phones of the same era. I think the 700 series that Paul refers to. I suggest the neons could be surge suppressors, clipping any transients over their firing voltage which is about 90. Someone more into telephone technology may be able to confirm.

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#142997 - 04/21/05 12:56 PM Re: Another old telephone
IanR Offline
Member

Registered: 12/06/04
Posts: 326
Loc: Palm Bay FL USA
"I suggest the neons could be surge suppressors, clipping any transients over their firing voltage which is about 90. Someone more into telephone technology may be able to confirm."

I have seen these in phone systems before also. I asked my uncle (Who works for Ma Bell) a long time ago and, if I remember correctly, they are surge suppressors. Kind of like a controlled spark gap.
Ian

[This message has been edited by IanR (edited 04-21-2005).]

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#142998 - 04/21/05 03:28 PM Re: Another old telephone
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
That is the GPO No. 746 phone exactly, bar the NZ-specific stampings on the base and the backward dial. Even the connection block is the same as the ones which were used here.

The 746 was introduced around 1967 as a revised version of the 706, the latter having become the standard GPO desk set in the late 1950s when it displaced the old 300-series phones like the one in the other thread.

The most obvious external difference between the 706 and 746 to the casual observer is the shape of the case around the handset area, although obviously there were quite a number of other changes.

706 and 746 refer to the basic desk phones; other numbers in the 700-series were used for wall phones, PBX phones with extra buttons, and so forth.

You can see a range of 700-type phones here:
http://www.telephonesuk.co.uk/phones_1960-80.htm


Your phone has the later single-coil ringer, Does it have the bell adjuster on the front too?

The earlier 746 phones used the more common double-winding ringer, like this one .

The "mystery" devices in the black package are actually a type of thermistor, used as part of the regulator circuit (and the green unit you queried is in fact a rectifier package).

As for lighting up, if you look closely at those thermistors in a darkened room with the phone off-hook, you will see that they do actually glow!

Here's the basic 746 schematic:



On the earlier 706 model, the whole regulator circuit was on a separate small plug-in circuit board. This board had contacts on both ends, those on one end just linked across so that the regulator could be bypassed by simply reversing the board in its socket.

Click here for 706 Schematic .




[This message has been edited by pauluk (edited 04-21-2005).]

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#142999 - 04/21/05 03:40 PM Re: Another old telephone
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Forgot to add a note about the 746 colors. The GPO here supplied them in black, ivory, red, blue, a mustard yellow, two-tone green, and two-tone gray (just from memory). They were the standard types -- Odd variations were done for special purposes, as you can see in the link above.

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#143000 - 04/21/05 04:25 PM Re: Another old telephone
chipmunk Offline
Member

Registered: 07/20/04
Posts: 142
Loc: Southampton, UK
Not to blow my own trumpet here... but I have a page of phone wiring diagrams [including the 746] here .
Also, interesting to note the reverse dial due to NZ using revertive impulsing (where the number of pulses were the DIFFERENCE between the number dialled and 10) instead of the British and American method. I believe one or more of the Nordic countries may also have used that form of dialling? I know the look of that phone well, I have about 100 of them sat in the attic.

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#143001 - 04/21/05 05:14 PM Re: Another old telephone
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Hmm,
Very interesting.
Thanks for the links and the circuit diagram Paul, it all makes sense now.
Although the switch symbols are a little foriegn.
There were some versions of the 746 here that were wall-mounted and they had small metal hooks that held the reciever in place when the phone was not in use.
Yes you are right about the two-tone gray phones, these were the standard office phone, in just about every TV programme or movie made here at the time, you can see one of these phones somewhere in the room.
The phone that I pictured above is now surplus to requirements here, I removed it about 2 years ago when I upgraded the phone system here at home and ran the system in Cat 5e wire and installed RJ-11 jacks in my office, the lounge and my bedroom.
 Quote:
Your phone has the later single-coil ringer, Does it have the bell adjuster on the front too?

Ahh no it doesn't have one as far as I'm aware.
Speaking of odd variations, I'm all for nice decoration, but isn't this taking things a tad too far?:





[This message has been edited by Trumpy (edited 04-21-2005).]
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Let's face it, these days if you're not young, you're old - Red Green grin

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#143002 - 04/22/05 02:48 PM Re: Another old telephone
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
I don't like that at all! It looks like a telephone version of the over-elaborate brass covers you can buy to fit over existing white wall switches.

Still, under all that decoration you have a nice old 706 telephone. Notice the difference in the cradle area which I mentioned before.

 Quote:
There were some versions of the 746 here that were wall-mounted and they had small metal hooks that held the reciever in place when the phone was not in use.

Have a look at the link above, you can see a red 706 version (without dial) like that. The 711 and 741 (also pictured on that page) were the more common wall types, being based on the 706 and 746 respectively.



[This message has been edited by pauluk (edited 04-22-2005).]

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#143003 - 04/22/05 02:58 PM Re: Another old telephone
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
 Quote:
Not to blow my own trumpet here... but I have a page of phone wiring diagrams

Blow away!

 Quote:
Also, interesting to note the reverse dial.....

In my younger days, before I had learned of the backward NZ dial, I wondered why Auckland had been assigned STD code 09. It seemed kind of odd (bearing in mind that in Britain we were all used to London having the shortest possible code 01).

Of course, it makes perfect sense once you see this. I would still find an NZ rotary dial odd though -- Just too used to American/British I suppose.
 Quote:
I believe one or more of the Nordic countries may also have used that form of dialling?


Sweden used a dial with the numbers running upwards as normal but with zero at the beginning, i.e. UK positions 1-2-3-4-5-6-7-8-9-0 corresponded to 0-1-2-3-4-5-6-7-8-9. Again, I remember seeing their emergency number 90000 and wondering why ? Makes more sense when you consider that it would be just like dialing 01111 here.

Re the "octothorpe," the reason it's sometimes called pound is because in the U.S. the symbol can be seen after a weight as shorthand for "lb." And of course, I'm sure you're aware of BT's annoying habit of calling it "square."

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