Simplex 4004 Compatibility Questions

Hey everyone,

I was looking at the 4004 FWD and couldn’t help but notice that the 2901 series horns is not compatible with the 4004. I was a bit dismayed because I had been planning to imitate my schools system on my new system at some point, but I don’t want to risk damaging or breaking this panel. This panel was manufactured in 1999, so the compatibility issue makes sense, but I can’t help but wondering how many buildings had to install new devices if they were to upgrade to a 4004 from say, a 4001.

So if the 2901 series electromechanical horns are not compatible, can I still use these devices on my system, or should I just not risk it?

HOWEVER, I did see that the 4901 and 4903 series is compatible, so would, say, a 4903-9401 or 9219 or a 4901-9805 electromechanical horn be compatible with the panel or would it still go haywire like the earlier mechanical horns? If so, I might consider purchasing a 4901-9805, but if only electronic horns are compatible, I don’t want to make that purchase. Trust me, any compatible mechanical horn is better than none, so if the 4901 series is compatible I will probably buy one.

Also, the Gentex strobe plates (4903-9104/5 and the 4903-9101) are compatible, right? Are the 2903 series compatible as well?

Thanks everyone for your help!

I will be using all compatible Simplex electronic horn/strobes until I hear otherwise, just to be safe.

I looked at the FWD for 4001 and 4004. I don’t see much difference. As far as I can tell 2901 devices are listed as compatible with each panel. Both show “4051 horn (2901)” as compatible. Simplex originally had a 6 digit sales number for devices (####-##) and later converted to an 8 digit system (####-####). All existing devices that were carried over simply switched numbers. Hence the “4051 horn (2901)” designation on the FWD. I think you will be OK as long as you don’t use any really old devices that don’t have internal suppression in them (usually an MOV across the coil).

There was a learning curve between the older relay operated panels like 4208 and the next generation 2001, 2100, 2120 electronic panels. Older electromechanical horns, bells, chimes, door holders, etc did not have suppression devices in them. They could produce high voltage spikes when the magnetic field collapsed on the coils in them. A similar inductive discharge system fires the spark plugs in your car. The relay operated panels did not have an issue with that. The electronic panels are sensitive to these back EMF spikes so need devices with internal suppression. In the changeover to electronically operated panels while the vendors were adding suppression I added a lot of diodes to door holder circuits.

Thanks! That helps me a lot.