Burgot alarm autodialler record

[TonyDuell]

I've got a late-ish Burgot burglar alarm autodialer here. It's basically a semi-automatic record player.

There's a turntable driven by a DC motor through an idler wheel. A pawl operated by the turntable spindle operates a camshaft which controls the pickup arm and operates various microswitches. There's also a cam with 9 notches on the turntable spindle which operates a switch contct, this is enabled by one of the microswitches on the camshaft for 3 revolutions of the turntable to dial 999. When the camshaft has got the 'pickup lowered, play record' position, the pawl is disengaged and the camshaft stays in that position.

Once triggered it plays a record until the pickup gets to the centre grove. A contact then completes a circuit which stops the machine. To reset it for future alarms you put a key into a lock on the front of the case and turn it. This operates another microswitch to start the motor and engaages the pawl again. The camshaft lifts the pickup and moves it back to the starting point, then a microswitch stops the motor and turns on a panel lamp to show it's reset. You then turn the key back to 'run' and remove it.

The 'deck' is a thick PCB. It carries a couple of relays to control the motor. There's a daughterboard with a couple of germanium transistors to amplify the signal from the pickup cartridge. And another board, somewhat later in design I guess with silicon transistors to detect a cut phone line, trigger the alarm bells, etc.

Anyway, I've got it working electroncially (No way will I connect it to the public telephone network of course, I've had it working on the bench) and cut a key to reset it.

What I can't figure out is the spec of the record (I don't have the original one). I ran the turntable for 1 minute and counted the operatations of the pawl -- 34, so I guess it's 33+1/3 RPM. But the pickup skates over the surface of a microgroove record. Either the stylus is very worn (it is still there!) or the thing used a standard groove ('78 size') disc. That could make sense, it would be a one-off recording and most such discs were standard groove I think.

Does anybody know what the disc was?

[trsomian]

I have never seen one of these in action, but a man I used to work with who had been in the alarms business previously had the remains of several of them. I understood from him that they played 45rpm singles, and the choice of music told the operator whose machine was calling. I have the little electronically commutated motor from one of them, and it has a speed control on the edge of the board. The man I worked with is long gone, so, sorry, but I can't ask him for more details. I would try and measure the turntable speed, inspect the stylus carfully, and go from there.

[G6fylneil]

I remember seeing parts of "record player" auto dialers in the early 1970's at an alarm company I worked for. We never had to repair any. The dialer cam. bit looked like part of a standard BT dial mechanism.

There is a clip in Tim Hunkins "Secret Life of the Telephone".

[TonyDuell]

I think there were several models. Even later ones used an endless loop tape cartridge I think.

The one I saw in a video on-line had a normal telephone dial with a device that located in the '9' hole, turned clockwise to stop, then released and repeated 2 more times.Mine has a more sane arrangement of a dialer cam on the turntable spindle.

Since this model directly dials the emergency number (and to have it dial anything but the same digit repeated would make it a lot more complicated) I doubt it ever played music officially. I understood it was a speech record of the form 'Police, Police <pause> Break-in at <address>' probably repeated a few times. Since this would be a one-off recording, it could quite likely be a non-standard format, e.g. 'standard' grooves on a 7" 33rpm disk.

Mine clearly runs slower than 45rpm, and I don't think it's been 'got at'. The motor is a DC permanent magnet thing with a governor in it, tweaking that would be non-trivial, ditto replacing the motor pulley. Given that my approximate measurement gives close to a standard speed I am going to go with that for the moment.

I've attached photos of the unit in its case with the cover removed and of the pickup cartridge (does anyone recognise it?). Also the circuit diagram and connections that I traced out.

[Rubberfingers]

Here's somebody playing one of this automated alarm records on a standard deck https://www.youtube.com/watch?v=yuk0L9MO8pA

[G6Tanuki]

I remember seeing a clockwork version of something similar; when triggered it played its announcement until the clockwork motor ran out of 'wind'.

Had a carbon 'pickup' too, presumably the only way to get enough AF signal to feed a phone line.

[Heatercathodeshort]

I have a CLARION automatic clockwork unit. There is a notch on the edge of the turntable that engages a solenoid. When activated the solenoid releases the turntable at 78RPM. There are nine notches at the centre that activate a pair of contacts. As the turntable revolves it dials 999. The message is similar to the one RB has posted.
I would add that it disconnects the phone while playing the record leaning the phone itself dead. The crystal pickup has a matching transformer across the phone line.
I did post a picture of it a while back. John.

[Trevor]

in the mid 70s we had such a unit on our shops burglar alarm the engineer used to open it up and replace the batteries / test every 6 months or so
I was fascinated by it and thought it a wonderful invention Trev

[slidertogrid]

I have a metal 78 rpm disc from one of these automatic alarms. From memory it has recorded on it in a woman's voice something like " Police Police Police intruders have entered the premises of (xxx, followed by the address) Then repeats . Something like that anyway, it is a while since I played it. There is a second hole offset to the centre hole in the record which I assume is there to engage on a pin to prevent slippage. I assumed the record is metal to prevent it wearing out, how many times were they expecting to be burgled I wonder? in retrospect maybe it was because it was a bespoke record and that was how they were made?

[Roger Ramjet]

This takes me back to my early days as an alarm engineer. One company who I worked for had quite a few of these units out in the field. They were usually 12V dry battery powered and each record was custom recorded with the business or customers name address etc. The units were serviced every quarter which involved a battery load test plus message test to the appropriate police or *fire control room. Insurers always insisted on connection to a separate ex directory / incoming calls barred telephone line.
Unlike the BurgoGuard unit featured, the Modern alarm ones were fitted in a well built wooden case which made very good toolboxes to be had whenever a unit was upgraded.
More popular were the tape units which could be either an endless loop or 8 track cassette. For these the dial pulses were either derived from a tone pulse on the tape or an IC operating a reed relay on the control PCB. I even recall one vintage unit in a Leicester hosiery factory that had a WIRE RECORDER
*The same system was also used for the remote signalling of Automatic Fire Alarms with the message saying FIRE FIRE FIRE as opposed to POLICE POLICE POLICE.

[Kentode]

Tony, this model was on Talking Pictures TV last night in 'Dial 999'.

Filmed in 1965, it looks like a 78 rpm record which said (allegedly) "Police, Scotland Yard..."

The baddies were caught!

[Trevor]

The unit we had in Hi-fidelity stoke on Trent circa 1969 was much simpler than this but to be fair it did work
Trev