Quote:
Originally Posted by Neil Purling
What was the main use for the Ever Ready FLAG cell? I thought of something like a door bell system with a long wire run. Perhaps a replacement for a group of glass wet-Leclanche cells.
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In the UK, they were largely replacements for wet Leclanche cells for bell ringing, railway signalling, and intruder alarms.
One type of intruder alarm passed a current continually through a loop of wire in order to detect a thief cutting the wire.
The flag cells had to supply this current for weeks or even months between battery changes.
25 to 50ma was a common current for the anti-tamper loop. A separate set of cells rang the alarm bells if the loop was broken, and sometimes telephoned the police*
It was common practice to fit new cells to the bell circuit every three months, the removed "bell circuit" cells should be virtually unused and were therefore fitted to the "anti tamper loop" for another three months.
After three months service in the anti tamper loop, the cells were discarded or used for any non critical purpose.
* A sophisticated MECHANICAL device was used to ring the police, spring powered and triggered by the electric alarm system.
This dialed a preset number, and then played a record down the phone line.
The record was specially recorded for each premises.
"Send police to high street bank, 123 high street anytown, intruders are in the bank" or something similar.
This message was recorded numerous times on the same record which once triggered played continually until the spring ran down.
Bank managers kids had plenty of well used but still useful flag cells. Some firms donated the old cells to a school.