Experiments around the piezeoelectric effect, both sensors and transducers.
Paper with lots of detailed info.
For a capacitive sensor like a piezo element, a Charge amplifier is better than a voltage or current amplifier.
Gain is G = Cinput / Cfeedback. It is neccesary to limit the DC amplification using.
And to correct for input bias causing DC offset on output, R1 == R2, where R1 is on the negative input connected to.
It may be desirable to add another (voltage) gain stage after the charge-amp, to maybe bring output up to line level.
Parts:
Ideas:
- Put double pads on feedback capacitor slot, to allow modifying/testing alternate values
- Can one make a "socket" for SMD capacitors, that allows switching them out?
References:
- DIYAudio: Guitar charge-amp preamp, with schematics and some good commentary
- Electric violin charge-amp preamp
- Texas Instruments: Signal Conditioning of Piezoelectic Sensors
- DigiKey: Fundamentals of Piezoelectric Shock and Vibration Sensors
Music
- Acoustic or electric guitar pickups
- Electric violin pickups
- Piano contact mic
- Electronic drum velocity sensitive trigger
- Pickup for spring reverb
Digital fabrication
- Vibration sensing of CNC spindles, for auto-calibration
- Touch-probe measurements for 3d-printer using differences in free-running and touching resonance
Parts
- Input protection diode, or zener. SOD-123 nice size, around 3.5mm, similar to 1206 Farnell: Zener 3.3v Farnell: Signal diode
- Speakers and buzzers
- Ultrasound transducer vaperizators, for aeroponics
- Micro-pumps and droplet valves
There are many recipies to make Rochelle salts, which are piezo-electric.
- http://makezine.com/2008/07/31/how-to-make-piezo-crystal/
- http://www.seawhy.com/xlroch.html
- https://www.youtube.com/watch?v=K3G2QM5a-9U
- Very detailed
Rochell salts are Potassium sodium tartrate, which can be purchased directly Amazon.
It can also be made from two fairly common ingredients
- Potassium bitartrate "Cream of tartar"
- Sodium carbonate "soda ash" or "washing soda", which can be make easily from sodium bicarbonate.
This should be usable for simple piezo sensors, like for triggering samples/drums.
Some cool things could be possible when synthesizing the piezo elements / crystals oneself. For instance, can possibly create a shape that is needed / desired, both for astetic effects and to make particular objects. Say like a speaker driver.
One could possibly embed electrical wire, solving the issue of