2 layers188 × 98 mm
2 layers69.3 × 66 mm
Tuning fork
oscimp/efts_tuning_fork1EFTS laboratory session: quartz tuning fork
- Size
- 69.3 × 66 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 34
- Nets
- 25
- Pads
- 136
- Tracks, vias
- 183, 8
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 9 Apr 2026
- Updated
- 2 Sep 2026
Overview
Tuning fork is an open-source printed circuit board by oscimp, from the oscimp/efts_tuning_fork repository on GitHub. It is a 2-layer board of 69.3 × 66 mm with 34 parts on 25 nets, routed with 183 tracks and 8 vias.
It is built around the NMA0512SC and TL072. Its parts include 9 connectors, 6 resistors, 5 capacitors, 4 ICs and 3 switches.
Main components
2
NMA0512SC
SIP-5P,19.5x6mm-40℃~+85℃ 10uF 12V 140kHz 19.6mm 1W 1kV 2 42mA、42mA 5.5V 6.1mm 7.5mVp-p 77% 9.9mm Plastic encapsulated type SIP-5P,19.5x6mm Isolated Power Modules ROHSMurataIsolated Power Modules
TL072
SOP-8-18V~18V 0℃~+70℃ 1.4mA 1.5nA 10V/us 10mV 2 2.5nA 3MHz 85dB SOP-8 Operational Amplifier ROHSGcoreOperational Amplifier
README
kicad/README.mdKiCAD schematic and board design files.
The non-plated through holes have been placed with a spacing compatible with installing the board on top of a Raspberry Pi 4/5 single board computer for a compact setup. Whether the heat dissipated by the processor will affect the resonator performance remains to be demonstrated.
The potentiometer closest to the audio input aims at adding a DC offset to bring the audio output within the range of the Schmitt trigger toggling voltage. Set the sound card output to maximum amplitude to increase chances of the Schmitt trigger toggling. The potentiometer further from the audio input is the negative impedance and should be tuned so that the oscillator starts (slowly !) at resonance frequency of the tuning fork.
The setup is designed to be assembled on a Rapsberry Pi 4/5:
Schematic
Parts
34| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3 | H1, H2, H3, H4 |
| 2 | 100n | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C2, C3 |
| 2 | Conn_Coaxial | Connector_Coaxial:SMA_Molex_73251-1153_EdgeMount_Horizontal | J5, J6 |
| 2 | SW_SPDT | Button_Switch_THT:SW_Slide-03_Wuerth-WS-SLTV_10x2.5x6.4_P2.54mm | SW1, SW2 |
| 1 | .5n | Capacitor_THT:C_Rect_L7.0mm_W2.0mm_P5.00mm | C4 |
| 1 | 10k/10 turns | Potentiometer_THT:Potentiometer_Bourns_3296W_Vertical | RV2 |
| 1 | 1k/10 turns | Potentiometer_THT:Potentiometer_Bourns_3296W_Vertical | RV1 |
| 1 | 1n | Capacitor_THT:C_Rect_L7.0mm_W3.5mm_P5.00mm | C1 |
| 1 | 1u | Capacitor_THT:C_Rect_L7.0mm_W2.0mm_P5.00mm | C5 |
| 1 | 3900 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R5 |
| 1 | 50k | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R6 |
| 1 | 560 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R2 |
| 1 | 6780+220 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R3 |
| 1 | 7400 | Package_DIP:DIP-14_W7.62mm | U1 |
| 1 | 7414 | Package_DIP:DIP-14_W7.62mm | U2 |
| 1 | 75 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical | R1 |
| 1 | 75 | Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_Horizontal | R7 |
| 1 | AudioIn | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J1 |
| 1 | AudioJack3 | Connector_Audio:Jack_3.5mm_Lumberg_1503_02_Horizontal | J8 |
| 1 | Conn_01x03_Pin | Connector_PinSocket_2.54mm:PinSocket_1x03_P2.54mm_Vertical | J9 |
| 1 | Iout | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J7 |
| 1 | LED | LED_THT:LED_D3.0mm | D1 |
| 1 | NMA0512SC | Converter_DCDC:Converter_DCDC_Murata_NMAxxxxSC_THT | U4 |
| 1 | OscOut | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J3 |
| 1 | SW_SPST | Button_Switch_THT:SW_TH_Tactile_Omron_B3F-100x | SW3 |
| 1 | TL072 | Package_DIP:DIP-8_W7.62mm_Socket | U3 |
| 1 | TuningFork | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J2 |
| 1 | USB_B_Mini | Connector_USB:USB_Mini-B_Lumberg_2486_01_Horizontal | J4 |
Questions
How big is the Tuning fork PCB?
It measures 69.3 × 66 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Tuning fork use?
34 parts, built around the NMA0512SC and TL072. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Tuning fork KiCad files?
From the oscimp/efts_tuning_fork repository on GitHub, at the commit this page was made from: the board is kicad/tuning_fork.kicad_pcb and its schematic kicad/tuning_fork.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Tuning fork design in my own project?
Its repository states no licence, so its author keeps all rights: ask oscimp before reusing the design.
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