Beware of fire hazard. I designed a DC-output UPS once which had to provide 24V and 12V output and there were at least several hundred produced - maybe as many as 1000. I had fuses on the 24V and a current-limited DC-DC converter on the 12V output. The outputs were often branched-off to smaller gauge wire and there were some instances of small fires due to shorts in very small gauge wire which people connected to the output terminals. If I had to do it over again I would have provided separately-fused (or otherwise current limited) outputs with a placard indicating a minimum wire gauge for each output. Interestingly it was submitted for regulatory approval and I had to make some changes but neither I nor the regulatory agency caught the rather obvious potential for misuse with small gauge wire= .. You might consider implementing a foldback or non-self-resetting current limit scheme. Foldback is where an overcurrent condition causes the output current to drop to a tiny "holding" value until the power supply sees the voltage climb indicating that the circuit is now open. Non-self-resetting would actually shut down the power supply completely upon overcurrent detection until a person pressed a reset button. Of course voltage drop with length may be a problem. I've been to two of these "Escape the Room" challenges and I was generally not impressed by the electrical implementation. Please do not cheap-out on the reliability and safety aspects! I'd use a closed-frame commercial power supply instead of an ATX supply. I've seen too many PC power supplies fail early. On Fri, Oct 13, 2017 at 12:15 AM, Justin Richards wrote: > Basically I am concerned about long 12v @ 3A & 5V @ 5A cable runs of abo= ut > 5m+ with random taps along the run of various lengths. > > My concern is the inrush currents, spikes and general nasties created > particularly at initial power on and when the loads are switched in an ou= t > during game play. > > >From peoples experience should I be implementing some sort of power > conditioning and if so what. > > I was considering placing inductors at the source in line with the 12v an= d > 5v to limit the sudden demand on the PSU when powering on. Perhaps a > sprinkling of small inductor at the input to each load. > > But I have no idea if this is required or what size the inductors should > be. I am thinking that ATX power supplies need to deal with massive powe= r > on surges or are motherboards designed not to do this. > > Any thoughts. The details are below. > > Cheers Justin > > I have asked to do all the tech for an escape room. > > All the puzzles have been bench tested and now close to installing in the > rooms. > > The PSU is a ATX power supply with a cheap Ebay ATX power breakout which > seems to work well. > > The loads are several Magnetic Locks, Arduino UNO's (no inbuilt reg) > controlling 4 RFID readers, 14 Wemos ESP8266's (in built 5v ->3.3V reg) > and 4 media players (no inbuilt reg) > > All the mags locks (12v @ approx 300mA) have been fitted with snubber > diodes (is that the right term) close as possible to the locks. > > Some of the puzzles require the Mag Locks to be normally energised so the= y > power up at power on. > > Due to the nature of the room it is difficult to reticulate 240A/C where > needed so decided to reticulate 5V and 12V DC. > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .