Can older Simplex devices be powered safely using FWR?

I recently acquired a 2903 strobe plate & a 2901-9806 mechanical horn. Is it safe to power older Simplex devices on FWR without risk of killing them?

The older horns should be okay, but they will sound scratchy. The strobe should be okay too.



Now, this is just conjecture on my part, but I think the reason why newer Simplex alarms don’t like FWR power is that they lack the circuitry to compensate for the rapidly oscillating voltage. Presumably adding that adds cost to the overall manufacture of the signals, and since Simplex panels put out filtered DC anyway, there isn’t much point to having them if they’re always gonna have filtered power.

Now that’s just stupid/cheap design when literally EVERY OTHER manufacturer HAS actually spent the money to put the necessary protection components in. Thanks for the info though.



The odd thing is is that even though I’ve been told by multiple sources that the Silent Knight 5208 (the panel I own & use) puts out FWR, all the mechanical horns I’ve hooked up to it sound smooth rather than raspy as they normally would on FWR. The late STR-SG told me a method of determining whether the output actually is FWR or not using a meter, but I have yet to check.

You can check by using a Spectralert Classic, I believe. It’s one of the few electronic horns that have an audible difference between filtered DC and FWR.

On filtered DC, the horn will sound smooth, at about an A-flat.

On FWR, it will sound slightly scratchy at a lower pitch, about a D.

This video from FireAlarmJrTech9 explains it pretty well.

Well, I DO actually have a Spectralert Classic, a ceiling-mount model to be exact, & I BELIEVE it’s sounded like Tech’s did on his second test, so I guess the 5208 outputs filtered DC despite Silent Knight’s claims of FWR.

I have a 9838. I have seen videos of crappy sounding horns on FWR. My 6227W hated FWR.