2 layers80.3 × 29.5 mm
2 layers50 × 100 mm
Project to use a tuning-fork as a clock reference, as accurately as possible
- Size
- 50 × 100 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 24
- Nets
- 41
- Pads
- 86
- Tracks, vias
- 0, 0
- Routed
- Not yet
- KiCad
- KiCad 6 (file 20211014)
- Created
- 27 Dec 2022
- Updated
- 26 Jun 2026
Overview
Ptf is an open-source printed circuit board by Cirromulus, from the Cirromulus/tuning-fork-clock repository on GitHub. It is a 2-layer board of 50 × 100 mm with 24 parts on 41 nets.
It is built around the NE555P and BC547. Its parts include 9 resistors, 4 capacitors, 3 ICs, 2 transistors and 2 inductors. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
2Parts
24| Qty | Value | Footprint | References |
|---|---|---|---|
| 2 | 100k | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P12.70mm_Horizontal | R8, R9 |
| 2 | 100n | Capacitor_THT:C_Disc_D4.7mm_W2.5mm_P5.00mm | C1, C4 |
| 2 | 10k | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P12.70mm_Horizontal | R4, R5 |
| 2 | 1M | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P12.70mm_Horizontal | R2, R6 |
| 2 | 1k | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P12.70mm_Horizontal | R1, R7 |
| 2 | 22mH | Inductor_THT:L_Radial_D7.8mm_P5.00mm_Fastron_07HCP | L1, L2 |
| 2 | 47n | Capacitor_THT:C_Disc_D4.7mm_W2.5mm_P5.00mm | C2, C3 |
| 2 | BC547 | Package_TO_SOT_THT:TO-92_Inline | Q1, Q2 |
| 1 | 1N4148 | Diode_THT:D_DO-35_SOD27_P7.62mm_Horizontal | D1 |
| 1 | 4.7k | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P12.70mm_Horizontal | R3 |
| 1 | Arduino_Nano_v3.x | Module:Arduino_Nano | A1 |
| 1 | BME280_breakout | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | IC1 |
| 1 | DS3231_breakout | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | U2 |
| 1 | NE555P | Package_DIP:DIP-8_W7.62mm | U1 |
| 1 | OSC Raw | TestPoint:TestPoint_Pad_D1.5mm | TP1 |
| 1 | OSC_Digital | TestPoint:TestPoint_Pad_D1.5mm | TP2 |
Questions
How big is the Ptf PCB?
It measures 50 × 100 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Ptf use?
24 parts, built around the NE555P and BC547. 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 Ptf KiCad files?
From the Cirromulus/tuning-fork-clock repository on GitHub, at the commit this page was made from: the board is pcb/ptf.kicad_pcb and its schematic pcb/MCU.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Ptf design in my own project?
Its repository states no licence, so its author keeps all rights: ask Cirromulus before reusing the design.
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