What is this electronic component?

Our Salter Bathroom Scales stopped working. I fitted new batteries and it was still dead so I opened it up to do some basic checks (not wet, power getting to circuit etc).

A component had come off the edge of the circuit board. I thought it was a piezo sounder device - disc shaped thin brass, about 1/2 inch dia.- wire to centre - soldered on the edge.

I thought it a bit odd as I had never heard a sound from the scales but I soldered it back on. Behold - they worked. Still no sound so I am wondering what the componenet might have been. Any suggestions.

I suppose I could take it appart and take a photo.......(SWMBO has mad me put my tools away!)

Reply to
DerbyBorn
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Piezo sounder is normally a brass disc but with a large, 50% of the area at least, ceramic disc mounted coaxially on top to which the second connection is made. A missing connection to such a device is not likely to stop the scales working.

Reply to
Bob Minchin

I think we're going to need that picture!

Reply to
Roger Mills

That is how it looked.

Reply to
DerbyBorn

Could they have been using a piezo sensor as a strain gauge?

Reply to
Jeff Layman

or to BALANCE a similar one so that you sensed differential strain...that's not unusual where sensors are prone to reading e.g. temperature as well. ;-)

Reply to
The Natural Philosopher

The Natural Philosopher wrote in news:m8tts3$288$1 @news.albasani.net:

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Sorry if this appears twice but I can't see my earlier post. I have noticed it says "BUZ" on the circuit board. It has never made a sound and the instructions make no reference to a sound.

Reply to
DerbyBorn

Just sounds like a piezo buzzer. Stick 6v across it and see if it squeaks. No other component will make such a sound.

Reply to
cd

A bare piezo sounder needs to be driven by audio frequency AC (just like a loud speaker). DC won't make any sound, except maybe a quiet crackle if you gently brush a wire against it making a poor contact.

Reply to
Andrew Gabriel

Oh, I think that you lost the thread (IYSWIM) in "Furred up DHW pipe!.

Reply to
Jeff Layman

That is strictly true - but most will have a built in oscillator so they work from DC. That sort will likely have some form of polarity indication like black and red leads.

Reply to
Dave Plowman (News)

Maybe it's the load cell that actually provides the weighing function of the scales.

Reply to
airsmoothed

In a way yes, I expect that the scales self activate when the they are stepped on and that vibration caused in the case and the component induces a voltage in it which is sensed by a low powered wake-up circuit, activating the main measuring circuits.

Reply to
fred

DerbyBorn pretended :

It was maybe being used as part of a cheap oscillator circuit, but I cannot think why.

Reply to
Harry Bloomfield

It's a bare sounder - no integrated circuitry.

Reply to
Andrew Gabriel

snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote in news:m8ua57$jaq$ snipped-for-privacy@dont-email.me:

I am left wondering if it is a sounder and the configuration of the circuit for this particular model (Salter 9000) just doesn't use the sound facility?

If it is to detect movement to turn it on - then I think this is done via the load sensors as a tap on the top plate activates it.

Reply to
DerbyBorn

Some scales have a separate battery, possibly rechargeable that can hold settings for older non flash memory, but itin that case the scales should have run with new batteries, so I cannot say. Are you sure its not mechanically connected to the scales like a strain gauge would be? Otherwise its odd that it came loose. Brian

Reply to
Brian Gaff

Its definitely a piezo transducer, but what its diong in that cct I cant imagine. Someone please crosspost to sci.electronics.design

NT

Reply to
meow2222

/Someone please crosspost to sci.electronics.design /q

< waves hand dismissively>

Jim K

Reply to
JimK

Quote from the manual

"Tap the platform centre (vibration activates your scale) and remove your foot."

It's acting in reverse as a microphone detecting vibration? It may explain why repairing the open circuit connection got the scales working again

Reply to
alan_m

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