Ukulele 1: DIY Piezo Pickup
Last Updated on November 18, 2020
ILIKAI IL-SOP-150G: Mahogany Solid, Soprano Ukulele
DIY Piezo with BF256B as Impedance Transformer to Reduce Hum:
Cased Piezo Ø24mmx5mm, Acrylic Double Sided Adhesive Tape 15mmx0.9mm, 2x5 Holes 2.54mm Pitch Universal Board (Self Processing), 3.5mm Stereo Aux Cable (80cm Length).
Connection between Tip and Ring makes no function with Mic In. No connection to Ring to resolve this. Or Ring with Sleeve. BUT, Mic In is for the mic, but not any piezo. To distinguish the difference between the uniquely active pickup and a mic, this issue may stay.
Acrylic Double Sided Adhesive as Another Side. Ideally, this side's texture should be plane. However, the thick acrylic may grip the roughness or design. The tape also seems to reduce noisy vibration.
BF256B, A JFET: 8.89mA at 3.22V (Gate on 0V). So the impedance is Approx. 365 ohms. To hide hum noise, place JFET close to the piezo element like an ECM. The low impedance signal in the cable reduces hum noise. G-S-D layout, seeming S-D reversible.
Updated on 11/18/2020: In my experience on making a compressor, BF256B doesn't seem to invert the phase. Whereas, 2SK209-BL inverts the phase. Also check out "LesPaul 7: Go Customize". I will remake this pickup and report as a post.
TODO: Epoxy Glue to Circuit to Strengthen?
ISSUE1: Right Palm Hits The Circuit on Playing (Reduce The Height)
ISSUE2: Sometimes No Picking Sound
Seems piezo's retaining static electricity. Add 1M ohms resistor at Gate of BF256B and GND to free static electricity.
Mic Amp with DIY Piezo: Download PDF File: Mic Amp Circuit (Replace MK1 to DIY Piezo and R1 to 500 ohms for The Peak at -9dBV Acoustic Recording)
Anyway, let's test recording by UCA222 and Raspberry Pi 3 using Audacity without noise reduction, software amplification, and any effect:
Because a naked piezo has Ag electrode, lead free can't be useful. Otherwise, your hot iron breaks Ag print...