Just thought I should share this,
About 5 years ago I did an Installation of an Intercom and Access Control for a Complex of 44 Flats.
The Intercom, 2 x Sets of RFID Tag Readers, and 2 x Maglocks. All running from a 16v Transformer, Commercial 12v Powersupply, and 12v 14Ah Battery.
The Maglocks need power continuously to stay locked.
After about 2 months, the commercial powersupply died (Thermal fuse died on it). I think Everything was drawing about 4A continuous.
So, Spent a couple of hours designing my own powersupply for it (Still using the same Transformer and Battery).
Including Toner Transformer & Etching my board.
Worked well, even though the bridge rectifier was a bit warm (small madeup heatsink sorted that out)
and the Linear Regulator could not be held comfortably (cant even hold on to its heatsink for too long).
Today (after all those years) I went to program in some more RFID tags, and decided that since I still had a key, I should just look if they had replaced it with 1 or 2 of the PowerStore Access Switchmode supplies. I was pleasantly surprised (totally shocked) to see my original powersupply in exactly the same place I left it, still working 100% (although it has a nice layer of dust on it after all those years).
I think it is about time they replace the backup battery though (With all the South African loadshedding, I am sure that battery cannot still be holding the doors locked for more than 20 minutes now....)
But anyway, I did not expect my creation to last so long..