Replies to This Discussion

Permalink Reply by Lane Martin on September 26, 2016 at 4:08am

Yes, a ceramic of some type.

I've never tried reassembling one of those. My gut reaction is that what you have there is an ex-pickup. Joined the bleeding choir invisible, etc.

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Permalink Reply by JL on September 26, 2016 at 6:16am

The white ceramic coating is the piezo crystal itself. 

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Permalink Reply by Mike "Honeyboy" Edwards on September 26, 2016 at 8:27am

Thanks for the feedback guys, lesson learned on my first build ,don't skimp on the important components.

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Permalink Reply by Shawn on September 28, 2016 at 12:24am

If you got it off amazon write a bad review or contact the seller they will probably send you a new one.

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Permalink Reply by Mike "Honeyboy" Edwards on September 28, 2016 at 12:38am

Shawn

yes I got it off Amazon, I have been on to the seller and they did offer a refund, I asked them to just send a replacement as I couldn't be bothered with a couple of £ refund.

To their credit they did get back to me promptly. will wait and see if I get a fully functioning one next time around but my future buys are going to be more local with the guarantee of a decent build.   

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Permalink Reply by Uncle John on September 28, 2016 at 12:38pm

The ceramic is what vibrates as the top vibrates and somehow the mechanical vibrations are converted to electronic sounds. 

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Permalink Reply by Timothy Hunter on September 30, 2016 at 2:32am

to use as a buzzer they need to be driven with an oscillator they change pitch if you change the oscillator frequency.
fortunately the also work in reverse , which is why we can use them as pickups/microphones.

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Permalink Reply by JL on September 30, 2016 at 3:33am

Interestingly enough, the piezo disks we use were manufactured to be speakers for smoke detectors, burglar alarms, alarm clocks, cell phones, earphones, PA system and guitar amp tweeters, etc.  We are creatively reusing them, much like chopping a wall-wart for a mag-pickup, or using a voice-coil speaker as a mic in a stomp-box.

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Permalink Reply by John Dill on October 27, 2016 at 2:45pm

The white coating is actually SILVER.This is why you can solder to it. Be careful because it is not thick.  It is applied over a ceramic substrate that is applied and fired on the brass disc.

I grew up working summers in the factory that started making these. When bent, say by twisting, just a little they produce a measurable voltage. I still have some that are larger than a .50 piece. and some as small as a pill. 

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Permalink Reply by Timothy Hunter on September 30, 2016 at 3:43pm

not sure now where i read about it but the first time i used a piezo as a pickup was around 1983... i tried to amp my acoustic 12 string. although it did work and it was surprising that it seemed to work no matter where i put it, even on the headstock. however the sound was not great. i had only started studying electronics then so i didnt know how to filter the screeching highs... lol.

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Permalink Reply by David L. on October 1, 2016 at 2:04am

This is the best UK seller I have found
£2.84 for ten prewired 20mm discs (my preferred size though she sells other sizes)
http://m.ebay.co.uk/itm/10-20mm-Piezo-Elements-Sounder-Sensor-Trigg...

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Permalink Reply by Anthony Waszkiewicz on October 1, 2016 at 2:29am

Same happened to me on two occassions, the wires came off the centre of the piezo. I re-solder mine back on. Both worked ok.

Piezoelectric materials can be divided in 2 main groups: crystals and cermaics.
The most well-known piezoelectric material is quartz (SiO2).

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