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Old 5th Jun 2018, 3:57 pm   #1
boombox
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Default So I've bought a pair of red BT intercom phones...

"A rare pair of fab retro 60's intercom phones. These came from my step dads old pub and one used to be behind the bar and the other one was in their upstairs function room. They had a super long cable to join them but it [the cable] was no longer usable after being taken out, it had been painted over for years etc so i threw it out. One gets plugged in as normal and the other has a battery. They just need a long lead to join them. I saw them being used years ago and requested them when they left the pub. I'm not very electrical so i never got a lead but i used to have the non battery one plugged in at home. I think the bells were silenced in it though as i had more than one retro phone plugged in at the same time and one ringer was enough! My brother in law did it and i can't remember exactly what he did."

They've not arrived yet but just wondering if there's any literature anywhere I could begin reading on these to hopefully get them pressed into service again. Bells and all would be ideal!

Also if anyone knows how they worked - i.e. was it like a hotline where you lifted one handset and the other end rang or...?

Thanks!
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Old 5th Jun 2018, 4:10 pm   #2
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Default Re: So I've bought a pair of red BT intercom phones...

These look like normal, GPO 706 type phones which someone's rigged up to run on a battery to make their own intercom.

The "intercom" labelling is not original, albeit nicely done.

We can't really tell you much more until we see inside them, but they look really smart, don't they? I think the red 706s are a really appealing design.

Nick.
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Old 5th Jun 2018, 4:11 pm   #3
Dave Moll
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Default Re: So I've bought a pair of red BT intercom phones...

If they're simply standard 706s wired to operate as an intercom, a picture of the wiring when they arrive should be a good start.
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Old 5th Jun 2018, 4:22 pm   #4
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Default Re: So I've bought a pair of red BT intercom phones...

Yes. I hope the conversion, if that's what it is, hasn't involved removing any crucial parts.
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Old 5th Jun 2018, 5:27 pm   #5
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Default Re: So I've bought a pair of red BT intercom phones...

Quote:
Originally Posted by Nickthedentist View Post
These look like normal, GPO 706 type phones which someone's rigged up to run on a battery to make their own intercom.
I beg to differ - see attached phones which appear to be a pair of similar phones. Produced by the BT Factory at Cwmcarn in South Wales in the early 1980's.

The 'Intercom' label looks to be the same style. If you look under the handset on the L/Hand red 706, you can see the same black 'addition' as in the R/H photo below.

Ian
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Old 5th Jun 2018, 9:19 pm   #6
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Default Re: So I've bought a pair of red BT intercom phones...

These look very familiar!

Still unclear to me how they worked. I'll take some pics of their innards when they arrive.
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Old 5th Jun 2018, 9:22 pm   #7
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Default Re: So I've bought a pair of red BT intercom phones...

Very nice.

I've got one in grey but I incomplete.

It's a 4-wire connection, and turning the dial in one causes the dial-off-normal springs to make a circuit sounding the DC buzzer in the other.

Hopefully they haven't been further modified so just joining the line cords matching colour to colour will get it working.

Mine has a jack on the back to connect an external 9v power supply. Sadly mine is disconnected from the PCB so I don't know where the battery connects in the circuit.

The bellmotor in mine is missing. And no internal diagram.
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Old 5th Jun 2018, 9:36 pm   #8
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Default Re: So I've bought a pair of red BT intercom phones...

A grey set that sold in April:

Picture attached.
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Old 5th Jun 2018, 9:58 pm   #9
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Default Re: So I've bought a pair of red BT intercom phones...

They only buzz as intercoms, because they work off a 9 volt DC battery - no AC ringing supply to ring a magneto bell.

I'm not sure what's in the rather sticky sleeved part, it may be some extra resistor(s).
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Old 6th Jun 2018, 2:30 pm   #10
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Default Re: So I've bought a pair of red BT intercom phones...

Quote:
Originally Posted by OscarFoxtrot View Post
A grey set that sold in April:

Picture attached.
Wonderful pic - is the original slightly higher res? Struggling to read some of the text. Thank you for posting it!
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Old 11th Jun 2018, 1:50 pm   #11
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Default Re: So I've bought a pair of red BT intercom phones...

Pics attached!
Couple more to follow.
Looks like the buzzers have been pinched.
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Old 11th Jun 2018, 1:51 pm   #12
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Default Re: So I've bought a pair of red BT intercom phones...

The last couple of pics as promised
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Old 11th Jun 2018, 5:23 pm   #13
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Default Re: So I've bought a pair of red BT intercom phones...

The buzzers are easily replaceable with 9 volt buzzers.

Unfortunately without a wiring diagram we'll have to work it out from first principles.
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Old 11th Jun 2018, 8:49 pm   #14
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Default Re: So I've bought a pair of red BT intercom phones...

I'm wondering at this stage if it might be better to use a VoIP adaptor configured for ringdown/intercom working - a) because I would prefer to use the mechanical bells to indicate an incoming call rather than a buzzer and b) because I'd rather not have to use the dial to initiate a call.
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Old 11th Jun 2018, 10:17 pm   #15
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Default Re: So I've bought a pair of red BT intercom phones...

These days, the VoIP adaptor configured as a ringdown circuit is probably the cheapest and easiest way of doing it. If you want to build your own

https://www.vintage-radio.net/forum/...9&d=1485945957

Not completely sure, but I think you have a missing regulator board in your 706. It plugged into the ABCDE contacts.

Refer
http://www.samhallas.co.uk/repositor.../0000/N806.pdf

which suggests that the phone should work de-regulated if BCD are connected together.

You also appear to be missing your bellmotors. Bell unmounted 59B ?
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Old 12th Jun 2018, 4:55 am   #16
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Default Re: So I've bought a pair of red BT intercom phones...

Given that 'normal' telephones 706 (and 746, which to J-random-public look much the same) are relatively common and intercom-modified ones are not, I would suggest buying a normal 706 if you want one to use on a VOIP adapter with a normal bell and restoring this pair as intercom sets (or selling them on).
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Old 12th Jun 2018, 9:15 am   #17
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Default Re: So I've bought a pair of red BT intercom phones...

I'm beginning to think you're right, Tony, if I'm missing all sorts of other bits. Shall I post them for sale on the forum?
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