Humming Alarm Panel

The hum could be either loose laminations on the transformer, or mains hum noise coming from a speaker/sounder. You need to work out which of the two first.

If the battery was not fully charged when installed into the unit, then it might be taking more current than usual to charge it up and thus might be causing some of the hum.

Hi Another common cause is if the panel is not fitted to a flat surface or a cable fouls it against the wall. Try light pressure against each corner & see if the hum increases or goes.As for battery IIR the Excell range will support a 7ah no problem if in doubt try

CJ

Hum is occasionally a problem with mains transformers.

1. Tke a hammer & cold chisel, and give the laminations a whack on each side. This jams the lams together, stopping hum.
2. Mount the transformer on rubber washers and it'll be much quieter.

NT

wrote

Thanks to all. Prefer the sound of tweaking the transformer screws rather than hitting the thing with a hammer and chisel. The panel is already mounted off the wall on flexible packers.

Phil

Doing that may make it worse.

TheScullster formulated on Friday :

Rather than hitting the laminations with a hammer....

On these small transformers there is usually a soft metal strap surrounding the laminations which is U shaped. Squeeze the sides of the U, perhaps in a vice.

or even

Rgds

Steve

OOPS!! sorry typo

CJ

dribble epoxy resin into the transformer.

One of those will work for you, one wont. We dont know which until you try them. Hammering lams is standard practice for silencing noisy transformers. Obviously one removes the thing from the kit first :) Pointed chisel required, not a flat edged one.

NT