Hey everyone,
I just bought a MeanWell power supply which outputs 24VDC (6.3 amps). Inputs 120 vac; 2.5 amps. Here is the eBay listing for pictures (it will take a couple days for it to get here); anyways, the question I have for everyone is as follows:
1. Does this thing output filtered D.C.? This is extremely important because I use electromechanical horns about 85% of the time… 2. I was planning to wire up a pull station, a System Sensor 4W-B smoke, and 2 a/v’s (4903-9101/2901-9846) and a Cerberus Pyrotronics MC-S17-S horn/strobe to it. I also forgot to mention I’m planning on wiring a light switch to it (to silence NACs easily), as well as my System Sensor MDL to the power supply (alldevices will be connected via a common negative wire which along with the positive wire (to supply power) will be connected to the device side of the MDL, while the power supply will be connected directly to Zone 1 (the horn control terminals are jumpered already) and this will be connected to the power supply. For that I’m just wondering if the schematic will work….I’ll work on a diagram later, but I’ve got sports practices for two hours in the morning and afternoon 6-8AM EST and 2:45-5 PM EST in the afternoon, so I’ll work on my wiring for now and check back when I can.
According to the datasheet, this power supply has a max ripple of 0.15V, so it may not supply the “cleanest” possible power, but then again you aren’t running sensitive computer equipment with it either. It is far better than true FWR current. You shouldn’t be able to hear the difference on any of your horns.
For reference, most high-end filtered DC power supplies I’ve seen keep the ripple under 5mV (.005V).
Thanks for the input. It’s good to hear that it will not destroy my devices :D. I know that the 9 volt battery method I used earlier wasn’t all filtered D.C. because there was audible sound changes. I do look forward to using my Simplex electromechanical devices on it.
Batteries are one of the few power sources that give out true DC power. The sound changes were probably a result of the battery current draining as you ran the alarm.
If I am correct, I do not believe that Full Wave Rectified power fries mechanical horns, it just makes them sound not as good as they should. I’ve heard that FWR only fries newer simplex stuff but again, I know a few people who run 4903’s on their fire lite panel and it’s perfectly fine.
I suppose that makes more sense than them just frying on the spot (which is what I’ve heard about FWR power supplies.)
Now that begs the question, if you power a newer Simplex device off an FWR power supply, will it still be damaged and eventually fail even if you no longer power it with FWR? In other words, if you power it only once with FWR, but power it all subsequent times with filtered DC, will the signal die?
My gut feeling is that the device will retain whatever damage was done while FWR power was applied, but the clean DC will not do further harm to the circuitry. However, I guess the question comes down to whether or not the existing damage is enough to eventually degrade the performance of the device and cause it to cease functioning.
For a comparison, I would consider any device that has been exposed to a power surge to be permanently damaged. As an example, think of those videos where a green LED is turned yellow or red by exposing the device to a higher current. It still works afterwards, but no matter how long you power it at its rated voltage afterwards, you’ll never turn it back to green again.