[PD] Piezo, trigger, Arduino

Martin Peach martin.peach at sympatico.ca
Fri Jun 17 16:28:43 CEST 2011

I found that it works better if you put some kind of peak detector 
op-amp circuit between the piezo and the arduino.

See the peak detector circuit in here:

The diode rectifies the signal and the capacitor stretches it out so the 
arduino has time to measure it, the resistor drains the capacitor so it 
doesn't hold the peak forever.

Putting weights on top of the piezos increases their output, as does 
gluing them to a resonant object.


On 2011-06-17 08:53, Roman Haefeli wrote:
> Hi Pierre
> Actually, I wouldn't connect the piezos to an arduino, but to a sound
> card, because the piezos will likely give very very short spikes and the
> sampling rate of the analogIns of the arduino is quite low (don't know
> the exact value) compared to the sampling rate of a common sound card.
> Also, you have more control in Pd to build a trigger detection filter
> then on the arduino. Also you would likely get much lower latency with a
> good audio setup than with the atmega->ftdi->usb->comport path. Also
> when using the soundcard, the latency is constant, while you would have
> glitches with the arduino.
> I'd be glad to hear other opinions, though, since my thoughts are purely
> theoretical. I haven't implemented a piezo-based trigger, neither with
> sound card nor arduino.
> Roman
> On Fri, 2011-06-17 at 14:27 +0200, Pierre Massat wrote:
>> Dear List,
>> This is yet another question about Arduino. Sorry about that.
>> I want to use piezos to trigger samples using my arduino board. I want
>> the trigger to be sensitive, and a quick google search seems to show
>> that piezo is the way to go.
>> Does anybody have any experience with piezo triggers (what type of
>> piezo, isolating each piezo, etc.)? I will hit the piezos with my bare
>> fingers (no drumsticks or anything like that), but i guess it doesn't
>> really matter since i can control the threshold within Pd.
>> This last sentence is just to make sure that everyone knows i'm
>> talking about piezos in case there wasn't enough occurences of the
>> word in my message.
>> Cheers!
>> Pierre
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