2 layers233.7 × 172.2 mm
Overcycler3
gligli/overcycler
Affordable DIY polyphonic hybrid single cycle / analog synthesizer
335 parts45GPL-3.0
2 layers72 × 57 mm
Tod
kmzbrnoI/todDCC Track Occupancy Detector
- Size
- 72 × 57 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 66
- Nets
- 46
- Pads
- 154
- Tracks, vias
- 250, 28
- Pours
- 6
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 5 Oct 2022
- Updated
- 31 Jul 2026
Overview
Tod is an open-source printed circuit board by kmzbrnoI, from the kmzbrnoI/tod repository on GitHub, published under the CC-BY-SA-4.0 licence. It is a 2-layer board of 72 × 57 mm with 66 parts on 46 nets, routed with 250 tracks and 28 vias.
It is built around the BC817, BC856B and RS605. Its parts include 20 resistors, 14 diodes, 8 capacitors, 8 transistors and 4 connectors.
Main components
3README
README.mdTOD – DCC Track Occupancy Detector
TOD is a DCC-only track occupancy detector for model railroad.
Basic features:
- Up 4 tracks
- Galvanically separated outputs
- Section occupied = output grounded
- No special power supply required
- Maximum track current: 3 A continuous without passive cooler, 5 A continuous with passive cooler.
- Could be divided into pairs with separated J&K
- Easily automatically-mounted-parts via JlcPcb
This repository contains schematics & PCB layout of TOD PCB.
Design
Schematics & PCB are designed in KiCad 8.
Production
PCB is prepared to be automatically assembled in JLCPCB.
SMD parts on bottom side should be assembled. Each SMD part has its LCSC_ITEM
attribute set.
$ make fabAuthors
TOD is designed by Model Railroaders Club Brno, Jan Horáček. Inspiration from Vladimíř Soukup, Zababov.
Recommended quality check procedure after manufacturing
Use 15 kOhm resistor as a load. Use DCC 15 V. Use standard room temperature.
- Check LED reaction for de/occupation of each track circuit.
- Measure voltage output – occupied voltage should be below 0.5 V.
- Check connection of J, K, GND.
License
Content of the repository is provided under Creative Commons Attribution-ShareAlike 4.0 License as openhardware project. You may download any data, contribute to the project, create PCB yourself or even sell it yourself.
Parts
66| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | 1N5819 | Diode_SMD:D_SOD-323_HandSoldering | D1, D3, D5, D6, D8, D9, D12, D13 |
| 8 | 82k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R4, R5, R9, R10, R14, R15, R19, R20 |
| 4 | 10n/25V | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1, C3, C5, C7 |
| 4 | 22R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R6, R11, R16 |
| 4 | 22u/25V | Capacitor_THT:CP_Radial_D5.0mm_P2.00mm | C2, C4, C6, C8 |
| 4 | 330R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R2, R7, R12, R17 |
| 4 | 3k9 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R3, R8, R13, R18 |
| 4 | BC817 | Package_TO_SOT_SMD:SOT-23 | Q2, Q4, Q6, Q8 |
| 4 | BC856B | Package_TO_SOT_SMD:SOT-23 | Q1, Q3, Q5, Q7 |
| 4 | LED | LED_THT:LED_D3.0mm | D2, D7, D10, D14 |
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3_Pad | H1, H2, H3, H4 |
| 3 | SJ | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1, JP2, JP3 |
| 2 | 2xMVE252 | TerminalBlock_Euroclamp:MVE252-5-V-2x | J1, J3 |
| 2 | MV133 | TerminalBlock_4Ucon:TerminalBlock_4Ucon_1x03_P3.50mm_Horizontal | J2, J4 |
| 2 | PC827 | Package_DIP:DIP-8_W7.62mm_LongPads | U1, U2 |
| 2 | RS605 | Diode_THT:Diode_Bridge_Vishay_KBU | D4, D11 |
The 63 most common of 66 parts.
Questions
How big is the Tod PCB?
It measures 72 × 57 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Tod use?
66 parts, built around the BC817, BC856B and RS605. 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 Tod KiCad files?
From the kmzbrnoI/tod repository on GitHub, at the commit this page was made from: the board is tod.kicad_pcb and its schematic tod.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Tod design in my own project?
Its repository publishes it under the CC-BY-SA-4.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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