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had a nice page in oldwiki, here's a reboot. im placing it for now.

a lot of the info starts from {{tamiwiki:projects:collinshandmade_electronic_music.pdf|collinshandmade_electronic_music.pdf}}, if there is a mention to chapter number below, it's from this ebook.

=== Piezo ===
see: how to make a contact mike: using piezo disks to pick up tiny sounds, chapters 7-8

=== contact-mic-circuit ===

{{ youtube>CKZPcnwD57U}}
<blockquote>{{:tamiwiki:projects:pasted:20231125-132220.png?0x300}}

<cite> [[https://www.homemade-circuits.com/diy-contact-mic-circuit/|homemade-circuits.com/diy-contact-mic-circuit]] \\
and https://www.youtube.com/watch?v=CKZPcnwD57U </cite>
</blockquote> 

<blockquote>amplification and distortion: a simple circuit that goes from clean preamp to total distortion 

{{:tamiwiki:projects:pasted:20231125-130336.png?0x300}} 
<cite> {{tamiwiki:projects:collinshandmade_electronic_music.pdf|collinshandmade_electronic_music.pdf, chapter 23}}  </cite>
</blockquote> 

==== more ====
  * http://www.mo-seph.com/projects/piezocrystals
  * https://www.zachpoff.com/resources/alex-rice-piezo-preamplifier/
  * https://till.com/articles/PreampCable/

<blockquote>
{{:tamiwiki:projects:pasted:20231126-002227.png}}

A piezo element can be thought of as a sound-dependent voltage source in series with a large capacitance of about 15nF. Here the trouble starts. You need to put this into a load which is higher than the impedance of the series capacitor at the lowest frequency of interest. If that is 20Hz, since the impedance of the capacitor is 1/2pifreq*C then you want that to be > 530k. I’ve terminated mine in 3.9M because that’s what I had to hand.

<cite>http://www.richardmudhar.com/blog/using-piezo-contact-mics-right/</cite></blockquote>