4 layers500 × 34 mm
2 layers170 × 90 mm
Timer v2
sudochamp/enlarger-timerAn f-stop calculation capable darkroom enlarger timer. Designed to switch mains voltage to be a drop-in solution.
- Size
- 170 × 90 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 51
- Nets
- 57
- Pads
- 175
- Tracks, vias
- 345, 28
- Pours
- 4
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 1 Apr 2024
- Updated
- 17 Oct 2025
Overview
Timer v2 is an open-source printed circuit board by sudochamp, from the sudochamp/enlarger-timer repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 170 × 90 mm with 51 parts on 57 nets, routed with 345 tracks and 28 vias.
It is built around the MAX7221CWG+ and SC10-21SURKWA. Its parts include 13 capacitors, 7 resistors, 7 ICs, 5 switches and 3 connectors. It belongs with the STM32 boards of this library.
Main components
2
MAX7221CWG+
SOIC-24-300mil0℃~+70℃ 10MHz 4-Wire Serial Interface 4V~5.5V Adjustable Glow、Common Cathode SOIC-24-300mil Digital Tube Drivers ROHSMaxim Integrated (Analog Devices)Digital Tube Drivers
SC10-21SURKWA
DIP-101 1 34mmx24mmx10.5mm 7 Segment 75mW Common Cathode Red DIP-10 LED Segment Displays ROHSKingbrightLED Segment Displays
README
README.md[!WARNING] This project is a work in progress. It functions, but not where I want it yet.
Darkroom Enlarger Timer
Built to address a simple problem. I just needed a simple timer that could do stop calculations and was accurate enough to be used in a darkroom.
It will need an off-the-shelf AC/DC power supply for the 120/240VAC to 12VDC conversion.
Parts
51| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | 100n | Capacitor_SMD:C_0603_1608Metric | C1, C3, C5, C6, C7, C8, C11, C12 |
| 4 | 1k | Resistor_SMD:R_0603_1608Metric | R1, R2, R3, R6 |
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3 | H1, H2, H3, H4 |
| 4 | SC10-21SURKWA | 7_segmeng:SC10-21SURKWA | U3, U4, U5, U6 |
| 2 | 10k | Resistor_SMD:R_0603_1608Metric | R4, R5 |
| 2 | 10n | Capacitor_SMD:C_0603_1608Metric | C9, C10 |
| 1 | 10u | Capacitor_SMD:C_0603_1608Metric | C2 |
| 1 | 10u | Capacitor_SMD:CP_Elec_4x5.4 | C13 |
| 1 | 4.7u | Capacitor_SMD:C_0603_1608Metric | C4 |
| 1 | 51k | Resistor_SMD:R_0603_1608Metric | R7 |
| 1 | EXPOSURE_TIME | Rotary_Encoder:RotaryEncoder_Alps_EC11E-Switch_Vertical_H20mm | SW3 |
| 1 | G*** | kibuzzard-66150B8E | kibuzzard-66150B8E |
| 1 | G*** | kibuzzard-66150C19 | kibuzzard-66150C19 |
| 1 | G*** | kibuzzard-66150D04 | kibuzzard-66150D04 |
| 1 | G*** | kibuzzard-66150C52 | kibuzzard-66150C52 |
| 1 | G*** | kibuzzard-66150CEE | kibuzzard-66150CEE |
| 1 | G*** | kibuzzard-66150B89 | kibuzzard-66150B89 |
| 1 | G*** | kibuzzard-66150C9A | kibuzzard-66150C9A |
| 1 | G*** | kibuzzard-66150BD0 | kibuzzard-66150BD0 |
| 1 | G*** | kibuzzard-66150C4D | kibuzzard-66150C4D |
| 1 | G*** | kibuzzard-66150BA4 | kibuzzard-66150BA4 |
| 1 | G*** | kibuzzard-66150B83 | kibuzzard-66150B83 |
| 1 | LD1117S33TR_SOT223 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U1 |
| 1 | LOGO | LOGO | G*** |
| 1 | MAX7221 | Package_SO:SOIC-24W_7.5x15.4mm_P1.27mm | U7 |
| 1 | PWR | Connector_JST:JST_VH_B2P-VH_1x02_P3.96mm_Vertical | J1 |
| 1 | RELAY | Connector_JST:JST_XH_B3B-XH-A_1x03_P2.50mm_Vertical | J3 |
| 1 | STM32C031K6Tx | Package_QFP:LQFP-32_7x7mm_P0.8mm | U2 |
| 1 | STOP+ | key_switches:SW_Kailh_Choc_V2_THT_nSilk | SW1 |
| 1 | STOP- | key_switches:SW_Kailh_Choc_V2_THT_nSilk | SW2 |
| 1 | SWD | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J2 |
| 1 | SW_SPDT | PCM_4ms_Switch:Switch_Toggle_SPDT_SubMini | SW5 |
| 1 | TOGGLE | key_switches:SW_Kailh_Choc_V2_THT_nSilk | SW4 |
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Questions
How big is the Timer v2 PCB?
It measures 170 × 90 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Timer v2 use?
51 parts, built around the MAX7221CWG+ and SC10-21SURKWA. 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 Timer v2 KiCad files?
From the sudochamp/enlarger-timer repository on GitHub, at the commit this page was made from: the board is pcb-files/timer_v2.kicad_pcb and its schematic pcb-files/timer_v2.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Timer v2 design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).