Hi all –
Recently I bought a Simplex 4906-9127 on eBay for a fairly reasonable price; I would like to use it with my MS-9200UDLS. I’ve also bought a 4905-9938 module for it. I’ve done some research, and I’ve noticed that you cannot under any circumstance use FWR for powering TrueAlerts, only filtered-DC. So my question is, how can I power it? I’ve been thinking of using 3 9-volt batteries going through my 9200’s silenceable alarm relay to make a makeshift non-FWR NAC, but I’m concerned that the 9-volt batteries could also fry both the 9938 and 9127. Can it? Or is it safe to do so? I’ve also seen a couple Youtubers with Firelite panels unplug their panel and have them solely battery-powered prior to alarming the circuit. I think this is also acceptable, but it’s not the most ideal for my setup. I also kinda want to avoid buying a $300, $400, or (heaven forbid) a $500 Simplex control panel – I like sticking with good ol’ Firelite 
. However, if the 9-volt batteries wouldn’t work, I’d be happy to take the no AC path, just cause I don’t want to waste the devices 
Anyways, I appreciate your guys’ help, and I hope you all stay safe out there!
I actually have an MS-2 and a couple TrueAlerts! What I used to do was just have the panel run on batteries and have it wired to the NAC. But recently, I discovered that the resettable power on my MS-2 is filtered. My panel is from the early 2010s so that might be something that happened in a revision. Anyone with an MS-2 (or any panel really) reading this, do not assume you have filtered DC unless you are absolutely sure. Anyways, I just wired the resettable power through the alarm relay and it’s worked fine each time I wired up my TrueAlerts.
Looking at a PDF of the 9200UDLS manual, it appears on page 33 section 2.3.3 it lists the resettable and non-resettable power as “24VDC nominal filtered”. I don’t want to break rule C13 or have you fry your TrueAlerts, so I’ll just suggest that you look further into this and see if your revision of the 9200UDLS has filtered auxiliary power. Though I imagine if their bear-bones lowest end panel has filtered resettable power, the 9200UDLS probably does too.
Cool, thanks! I’ll definitely look more into the manual and make a decision from there. Today I ran across Fire Alarm Tech’s Youtube video over how he used D Planet’s step-down buck converter on a nac and used the converter’s output straight to the 9938, so I’ll also do more research over that. Thanks again!
Gentex Guy is correct. The 2015 revision of the MS-9200UDLS service manual on Fire-Lite’s website says that the NACs are 24VDC nominal FWR, however the 24V special application power is filtered DC. The MS-9600UDLS provides filtered DC on the NACs. Be careful installing any 3rd-party device on a fire alarm panel, especially directly in line with an input or output circuit. Remember that NACs are supervised in standby, so power will be applied in reverse polarity so the panel can check for opens/shorts. If nothing else, you will need to polarize your filtering device with a diode, to prevent current flow through it in the wrong direction. If you do not, a few things can happen:
- Your filtering device is really well-designed and polarized/otherwise protected from the factory, so supervision voltage won’t affect it. Your panel may or may not generate a NAC trouble, depending on the resistance of the filter.
- Your filtering device is not affected by reversed polarity, but appears as a short when a small voltage is applied in the reverse direction, tricking the panel into thinking the NAC is shorted. The panel will announce a NAC trouble, and since a shorted NAC would fry the panel, no power will be applied in alarm.
- Your filtering device contains a capacitor and is not polarized. Applying voltage in the wrong direction can cause serious damage to the capacitor in the filter, and in turn the filter could damage the panel and any devices connected to the filter outputs.
Also keep in mind that inserting a filter in line with the NAC may or may not completely prevent the panel from properly supervising the entire NAC.
I’d reccomend getting a CMF-301 control module and using the special application 24V filtered power as its source. The benefits would be this:
- The CMF will supervise your NAC in standby AND it will constantly supervise the separate 24V power supply. You’ll get a unique trouble if either of those circuits have a problem.
- You can program the CMF to operate as a traditional NAC or as a special notification circuit.
- You don’t have to worry about compatibility or damaging your panel with a 3rd-party filtering device.
- Your Simplex TrueAlerts connected to the CMF will run on filtered DC in alarm!
Awesome, thanks for the extra help! I’ve actually been meaning to get a couple cmf’s now just because I do have an sep-sw, so the TrueAlert would also benefit from one!