Forums › Life › Computers, Gadgets & Technology › Alarm lamp panel (for emergency PSU)
This is what I wanted the 24V LED lamps for; it is based on the alarm lamps in European telephone exchanges. On smaller ones used in hospitals, ports there are usually two alarms – big alarm and small alarm. The first has a noisemaker attached to it and means that whatever problem has occured will be stopping many people using the telephone across the site; the second is something important which needs attention but you shouldn’t get too alarmed about it 🙂
On big exchanges in towns and cities (that both your fixed and mobile phones connect to) there are usually 3 big alarms (A1,A2,A3) and 2 observation alarms (O1, O2). how they operate can be selected with the telephone exchange software.
my panel has just the 3 alarms; there currently are only two signals from a clever device the French made that keeps a 24V accu charged up via a 230V to 27.6 V DC power unit; as well as monitoring the 230V AC. A -24V DC supply available even if the 230V mains is off for as long as the accus can deliver it (when their voltage is too low the power shuts off). I currently have this connected to a -24V DC to +5VDC converter to power an IP phone; another converter for +12V DC will be added to power some Arduinos and the lot put in my studio/workshop rather than the current arrangement where I have to keep charging smaller 12V accus
The emergency power unit an alarm signal if the 230V AC goes off (which I connected to A2 and A3) – the and another if the accu gets disconnected or is not working well (but there is still 230V AC to work the other power supply).
In telephone exchanges during 1980s/early 1990s (not all digital then and contained some very noisy equipment) it was often common practice to use PA loudspeakers (if not being used for announcements to call specialist engineers) to relay music; usually from a radio station of the national broadcaster as circuits for their music lines went through the same telephone exchange. the engineers had the choice of any radio channel they wanted; if the bulk of them were young it would be the “youth station” playing “specialist pop music” – by the 1990s was often a former pirate station.
Therefore whatever alarms were used had to be seen and heard over the noise of the exchange equipment and that of any loudspeaker systems..The track used below is from 1991. The rapper speaks English but with a European accent with a religious reference in the lyrics might hint it is from België (which made a lot of rave music back then).
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Forums › Life › Computers, Gadgets & Technology › Alarm lamp panel (for emergency PSU)