Blocking Sound From a Piezo

[MrAl]

Hi,

Anyone have any success in blocking the sound from a piezo? I mean mechanically, not electrically.
Epoxy, super glue, hot glue, foam, whatever that might have worked?

With the dynamic buzzers i have had great success in sticking something like a toothpick into the hole and that pushes on the diaphragm and that keeps it from moving at all, even a tiny amount. With the piezos however this doesnt work as well.
I've also used a tiny rare earth magnet which holds it from moving, but of course the piezo is not magnetic.

Cant disconnect the piezo so that's out, cant add resistance, nothing electrical. Has to be mechanical and preferably something that is reversible (but that's not mandatory). A second piezo to cancel the vibrations isnt really too feasible either.

 

[Nigel Goodwin]

A six inch nail and a hammer?.

 

[MrAl]

Hi,

He he, i'll have to try that

Is that reversible?

 

[strantor]

Tape a folded up shop rag over it, with several layers of duct tape.

 

[MrAl]

Hi,

That's a decent idea. I forgot to mention however that space is a little restricted. Maybe just the duct tape? Anyone out there care to try this at home? Wouldnt mind hearing the results.

 

[strantor]

I've done it, it works. Well, actually I didn't do it, someone else did. I'm the one who installed the alarm, on night shift. Then the day shift operator installed the rag & duct tape because he didn't like the alarm. Then the night shift operator put in a work order saying that the newly installed alarm wasn't working, and I had to go back and uninstall the rag.

 

[MrAl]

Hi again,


Ha ha, sounds like you had quite an adventure there with these things. I'll have to try that myself, in miniature. Thanks for the idea.

 

[ChrisP58]

What is the error condition that is causing the alarm to sound? Is the alarm trigger just to sensitive? Or is there some real problem that should be addressed at the root, so that the alarm goes silent on it's own?

 

[4pyros]

Hot Glue will do.

 

[KJ6EAD]

If it's part of an oscillator circuit, not just an output, preventing motion and therefore oscillation may have unintended consequences.

 

[MrAl]

Hi again,

Chris:
Good questions. It's not an alarm, it's the beeper inside a microwave oven. It's not my oven so i have to be careful whatever i do, i dont want to ruin their microwave oven, but there is a chance that silencing it permanently is ok. It's the loudest beeper i ever heard, and it beeps every time you press a key and beeps a whole bunch of times when the timing process is complete. It's quite obvious it is done without a beeper as the internal light goes out and the over stops making that little groaning sound they make.

KJ6EAD:
Yes i didnt want to alter it any more than necessary. I didnt want to disconnect it electrically for that same reason. I dont have a schematic so i can not access what would happen. So it looks like the only way it so muffle it as well as possible.
I thought about some special sound deadening foam, but that stuff is a bit too thick. There's not much room between the piezo which mounts vertical on the PC board and the side of the case, and on the other side of the piezo there is another component too. So there is like 3/8 of an inch on either side but that's about it. I also dont have a part number for this exact model piezo so it's hard to figure out what an electrical substitute (that doesnt procduce sound) might look like. Id' want to be fairly exact with this not guess.

Most annoying beeper on the planet.

 

[Mr RB]

It's a fairly common problem, sometimes the piezo's fail mechanically somehow and they resonate and get really loud. When i was in appliance repair people would bring items in and ask to have the buzzers made more quiet. I'll second the hot melt glue idea, it will hold on forever and you can adjust by amount whether you completely cover the buzzers hole or partially cover it.

On some occasions even after totally covering the hole it will still be louder than you want, you can then put a high value resistor in series with the piezo, I used to cut a track on the bottom the pcb and just patch a resistor on the PCB (in series). You may need quit a high value don't be surprised if it needs >100k, even up to 1meg. You may not have that option if it detects the piezo although I have never seen that on a microwave.

Maybe another option would be to solder in a different size or brand of piezo, that is much more quiet. And hot glue if needed.

 

[MrAl]

Hi MrRB,

I wasnt planning on a mod that involved any electrical alterations, but from what you are saying it sounds like you've had quite reasonable success with a resistor in series with the piezo. I might like to try this if it doesnt involve unmounting the whole circuit board.

Thanks for the detailed information.

 

[RichTheDude]

In a UPS we use often, it used a piezo to let you know it was running off battery power (kind of obvious when your outside...). I just removed it by placing the iron tip across both pins and pulling it out.

 

[Inquisitive]

How about a shot of expanding spray foam insulation. Warning It will not be reversible. But it would be soothing. I think decibel decrease would be equal to thickness of foam applied

 

[alec_t]

Bury it in loose sand.

 

[Mr RB]

Does that work on annoying wives??

Haha whoops I meant the expanding foam, not the burying in sand.

It was the part about the sound reduction NOT being reversible that got my interest...

 

[MrAl]

Hi,

Yeah expanding foam might help if the piezo never has to be restored.

Sand? Yeah sure i'd like to take that thing to the beach and see just how deep i could bury it and accidentally forget where i buried it later. Either that or see how far i can throw it out into the ocean waves, maybe some little fish would get his/her head stuck in the little hole and finally silence that beep. With my luck the current would bring it back into shore and i'd get a ticket for illegal dumping in the ocean.

 

[4pyros]

Will cockroaches eat it? Then you will not have to worry about restoring it. Maybe over heating it and melting it?

 

[rogs]

Does that work on annoying wives??
Haha whoops I meant the expanding foam, not the burying in sand.

Now you've mentioned it though, the sand does sound like an interesting option.......