It became apparent that the historical intruder alarm systems were extremely crude, considering the level of risk of the sites they protected, Banks, Jewellers, Building Societies, Museums, and Art Galleries to name but a few.
The two original companies had quite different solutions to the problem. Rely-A-Bell as the name suggests was an overt solution, obvious to any would be intruder with external sounders (bells) and large obvious metal control panels by the main entrance from which the system was set/unset, they made a lot of noise attracting attention to a break in and their deterrent relied upon intruders wanting discretion.
Burgot on the other hand were covert installations, a discreet polished wooden box housed the control equipment and had a polished wooden front door locked with a key, looking for all the world like a small wall mounted drinks cabinet.
The system used signalling to call the police and for many years intruders thought they were just unlucky when they had been caught in the act. Right up until the turn of the century it was not uncommon for the police to communicate “there’s a Burgot reporting from such and such premises, address etc.”.
Rely-A-Bell systems were incredibly crude in their design, the panel had a six volt dry cell battery inside the case, there were three dry flag cells providing four and a half volts located in a box at the other end of the property, these cells had a two core cable leading from them through every part of the premises to be protected.
Typically thin tubes fitted at four inch intervals across all the windows looking like security bars but in fact had wiring through them (known in the industry as frames), contacts in the doors, small switches that broke the circuit when the door opened, and wiring behind hardboard sheeting on vulnerable panels such as wooden doors (known as CC Wire).
When setting the system, a switch would be rotated to ‘test’ and a meter would show a green ‘ok’ condition, in test mode the batteries at the end of the line were connected in series with the battery in the panel, this provided enough electrical energy to pull in a relay (an electromagnetic switch), then the switch was rotated to ‘set’ position, this disconnected the internal battery and left just the end of line flag cells to hold the relay energised.
Should the circuit be broken by an intruder i.e. opening a door, the relay de-energised and the sounders rang, should the intruder close the door re connecting the batteries, the system continued to sound as the end of line cells could not re-energise the relay by themselves.
By modern day standards, these were crude indeed.
As Rely-A Bell systems reached the end of their expected life it was inevitable that they needed a lot of work to keep them operational and really needed replacing with a modern system.
The skill with which they had been installed originally was apparent, as every system would be wired in the same way, so the 2 core cable would always start at top left of a window frame and finish at bottom right, the joints at bottom right were accessible for testing with a meter. Simple checks to locate the circuit break would comprise of testing to see if the 4.5 volts from the batteries was present at the halfway point in the circuit, if yes then the break was nearer to the panel, if no then it was nearer to the end of line batteries.
If the engineer did not have a meter to hand it was common practice to use two tailors pins, holding them in contact with the joints bottom right and licking the pins, if you had a fizzing sensation there was voltage at this frame.
However when a customer did not want to pay for necessary remedial work, it was not uncommon for the resistance of the circuit to increase to a point where the end of line batteries could no longer hold the relay in ‘set’ mode.
A quick solution was to increase the number of batteries to overcome the failing systems resistance. Some sites had 30 or 40 batteries in place of the original 3.
A kind engineer, having deployed this solution may leave a note in the panel saying, “no tongue testing”. However, they were not always kind!
The Burgot systems utilised (believe it or not) a gramophone record player, in a locked box, hidden from sight in the premises.
These had a hot burned record which had been recorded with a message “Police Police Police, this is a Burgot automated intruder alarm reporting from the premises of (Joe Bloggs & Co, High Street Leeds)” and were connected to the companies telephone line.
When activated they dialled 999 and played the recording which repeated for a few minutes. The original versions were housed in polished lockable wooden boxes, used 10” Bakelite disks and were powered by dry batteries, when I arrived these were being changed for newer smaller metal box versions with 7” vinyl covered aluminium discs.
For high security systems, ‘direct line’ signalling was utilised, this comprised of renting a pair (a telephone line without connection to an exchange) from the GPO (now British Telecom) between the premises to be protected and the local ARC (alarm receiving centre), a secure manned room where alarm systems were monitored and the authorities notified should the need arise.
The direct line systems started out utilising a simple 24V connection between the customer and the ARC, when present, the system was not in alarm, when absent the premises were in line fault (possibly the line had been cut as a prelude to a break in) and when the voltage reversed the system was in alarm.
The system had its flaws, intruders who had been to college (prison) were learning electronics and had a greater appreciation of how systems worked.
They started opening the GPO boxes closest to the target premises and with a simple voltmeter that could identify which lines were phones (50VDC) and which were intruder alarms (24VAC), once identified, they would connect up a 24V truck battery which effectively disabled the signalling system.