sparky_75

They used them (originally) on the Railways for telecommunications - such as with remote telephones where there was no power and for block instruments to signal between signalboxes. I saw some factories - where they had their own internal phone system and exchange. Most - if not all early security alarm systems were battery only. It wasn't until BS4737 came in, that a requirement was made for them to be dual powered. Flag Batteries are about 40Ah; so you could get quite a bit out of them

This is an old AFA setup; possibly pre AFA Minerva days. AFA & Minerva merged together in 1969; but equipment remained to be installed with "AFA Burglar Alarm" and "AFA Security Systems" for quite a while after. With the involvement of EMI - the company name was officially changed during early 1973 to "AFA-Minerva - EMI". The installation pictured is a single circuit "G Type", the small box beloew the relay box has a red lamp on the top, beneath that a black knob (Circuit switch) and beneath that a barrel keyswitch. The red lamp warns you that a circuit is open, so don't turn the key! If the lamp was out when setting, it was safe to turn the keyswitch, setting the latch and bell circuit. Behind the panel, when the key was turned to "Arm", a metal bar rotated to wedge the above circuit switch - to prevent it from being switched off. The relay box above are the control relays - in most normal installations; this box was an AFA drum bell box (usually Black, or Blue). Relay on the LH side (above) is the Bells and Outputs relay, Centre Relay is the latch relay (in other versions of this box, this is a sealed Dublo relay) and far RH side relay is a low current relay - the circuit relay, energised by the end of circuit batteries. (3 flag cells). AFA did a multicircuit version of this - also available in Blue or Black; which could handle up to 10 circuits, and included a circuit test and panel meter. These boxes were often modifications to existing systems; where the drum would be removed; this box fitted and luxuries such as 24 hour Tamper and Panic circuits would be added, as well as a Lead Acid Battery and charger. There were still many of these installs in operation when I was at Thorn. We had loads on our books - and if looked after, were quite reliable. I removed one of the last ones in the midlands that was linked directly to a local police station. Not that it's any use to anyone, terminations - the first 12 are a drop down to the panel - wired in 12core. AFA-Minerva continued to make a Single G-Type and a Multi Circuit G-type (this could handle around 15 circuits and was the size of a large suitcase) until around 1976/77 - though still used Flag Cells - they also included electronics here and there as relay drivers in a bid to keep current consumption down.