Vintage Burglar Alarm

[M0FYA Andy]

On tonight's episode of the crime drama 'Dial 999', shown on Talking Pictures TV and dating from 1958, there were some excellent shots of the operation of burglar alarm. Triggered by the breaking of an infra-red beam, the mechanism was shown close-up, with the automated operation of a conventional dial mounted on the chassis to dial 999, and then the starting of a record (78rpm?) with the pre-recorded message of where the burglary was taking place.
Presumably state-of-the art in the 50s. Have any of these machines been preserved?

Andy

[McMurdo]

This has been covered on the forum before at some time. One was shown on the Hunkin/Garrod Ch4 series Secret Life of... and I forget which one. Telephone probably.

edit: Yes, telephone, 16:30s in
https://www.youtube.com/watch?v=7R9bHJfymjg

[M0FYA Andy]

Kevin, thanks for that link.
I'd venture to suggest that the clip in Dial 999 showed the dial operation a bit clearer!

Andy

[Cobaltblue]

There have been several threads on these in the past a couple are linked below:

https://www.vintage-radio.net/forum/...d.php?t=188396
https://www.vintage-radio.net/forum/...ad.php?t=35961
https://www.vintage-radio.net/forum/...ad.php?t=70200

The Dial 999 program was mentioned before in post #12 of the first link.

Cheers

Mike T

[M0FYA Andy]

Thanks!

Andy

[Roger Ramjet]

Hi Andy,

I used to service these 999 auto diallers in the 70's but I have never seen one with a traditional GPO dial. For the units that played a record, the dial [9] pulses were provided by a toothed wheel on the actual record deck which was switched in at the start via a separate relay.

Rog

[TonyDuell]

Yes, the Burgot unit I restored has an impulse cam and contacts on the turntable spindle. The attached photo shows the bottom end of the turntable spndle with the operatng link to the pickup arm camshaft removed.

I always thought that the 'twiddle the dial' mechanism n the film was ridiculously complicated and that there were clearly much easier ways to generate 9 line-breaks. But I suspect the Post Office insisted that the only way to generate dialing pulses was to use a telephone dial.

[Roger Ramjet]

Originally Posted by TonyDuell

Yes, the Burgot unit I restored has an impulse cam and contacts on the turntable spindle. The attached photo shows the bottom end of the turntable spndle with the operatng link to the pickup arm camshaft removed.

I always thought that the 'twiddle the dial' mechanism n the film was ridiculously complicated and that there were clearly much easier ways to generate 9 line-breaks. But I suspect the Post Office insisted that the only way to generate dialing pulses was to use a telephone dial.

Yes the Burgot unit was quite popular Tony, but once again I have never ever seen a unit that used a dial mechanism & would suspect this was added in the film [not watched it BTW] for dramatic license. The Burgot unit & other similar ones would have had to be PO Approved as part of a Block 52A order to connect to their network so no need for the insistence on a dial.

Workshop 999 message recorders did have a dial but these were for tape machines only. The dial pulses were inputted & converted to audio tones on the tape prior to the message announcement. The "dial tones"' were then filtered via the on board electronics & used to switch a reed relay. Other phone numbers other than 999 could also be added if needs be.

Rog

[TonyDuell]

I've never seen one with a dial mechanism 'in the flesh' either. Only on that film clip. It shows a normal telephone dial in a mounting with a mechanism that inserts a pin into the '9' hole, rotates to the stop, lifts the pin so the dial runs back to normal, resets and repeats a couple more times.

I wonder if the original PO requirement was to use the dial and a prototype unt (at least) was made and filmed. Then somebody realised how ridiculous that was and allowed the use of the impulse contacts/cam driven some other way. Of course the unit had to be approved, back then everything connected to a telephone line had to be.

[M0FYA Andy]

Very interesting discussion. I can't believe that the dial mechanism was added just for the film, it looks far too complicated to be anything but a real mechanism.

Andy

[Cathovisor]

The ones I remember from the 70s used a 45rpm record and were fully transistorised - one of my uncles owned a burglar alarm company and he used to install them.

[TonyDuell]

Are you sure it was a 45rpm record? The Burgot unit I have takes a 7" record, certainly, but I counted the turntable revolutions in a minute and got 34, which leads me to believe it's a 33+1/3 rpm disk.

Also the stylus looks intact but it skates over a normal 7" microgroove record which makes me suspect the original (which I don't have) was a standard groove (as more commonly found on 78rpm disks)record.


Going back to post #10, I would agree that the mechanism to operate the dial is far too complicated to be added just for the film. My guess is that it is a real dialing mechanism. Either it was made for a prototype burglar alarm and by the time they went into production the PO had decided to allow another method of producing the pulses or it was indeed used in a few production models but was quickly superseded

[Roger Ramjet]

What does surprise me is that the film showed in depth information on how the burglar alarm worked to the public arena.

Even up to this day & age, detailed info equipment technology is not normally made readily available to all & sundry (for obvious reasons).

Bit of a long shot but maybe the dial was deliberately added to confuse would be villains ?

Rog

[M0FYA Andy]

Could it be that by the time the programme was made (1958), the mechanism shown had already been superceeded by later designs? Given that the make of the alarm was clearly given, it must have had the full cooperation of the manufacturer. Perhaps they hoped it would boost their sales?

Andy

[McMurdo]

The one I linked-to in post 2 with the telephone dial (and the Dial 999 film) is a Burgot and Ch4 filmed it at the Science Museum stores, it's still in their inventory.
https://blog.sciencemuseum.org.uk/burglars-beware/

[Roger Ramjet]

Wow ! That link was fascinating Kevin,

It certainly looks genuine and given the date of 1939 clearly predates my time in the security industry.

My old boss used to work for Burgot so I will try to track him down, although I suspect the 999 dialler unit predated even his time.

It just goes to show how Vintage Tech can give more modern kit a good run for it's money.

Rog

[Cathovisor]

Originally Posted by TonyDuell

Are you sure it was a 45rpm record? The Burgot unit I have takes a 7" record, certainly, but I counted the turntable revolutions in a minute and got 34, which leads me to believe it's a 33+1/3 rpm disk.

No - it was high up and I was nine.

[Cathovisor]

I've just watched the episode in question and now I am left wondering why that convoluted method of dialling 999 was used when the GPO had the Autodial No.1 unit that would have been more sensible?