2 layers33 × 20.3 mm
CAPLIGHT01A
UniversalScientificTechnologies/ExpaLight
The red flashlight for night astronomy observations
14 parts2GPL-3.0
2 layers33 × 20.3 mm
CAPLIGHT01B
UniversalScientificTechnologies/ExpaLight2The red flashlight for night astronomy observations
- Size
- 33 × 20.3 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 15
- Nets
- 10
- Pads
- 60
- Tracks, vias
- 124, 16
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 5 (file 20160815)
- Created
- 8 Mar 2016
- Updated
- 19 Aug 2025
Overview
CAPLIGHT01B is an open-source printed circuit board by UniversalScientificTechnologies, from the UniversalScientificTechnologies/ExpaLight repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 33 × 20.3 mm with 15 parts on 10 nets, routed with 124 tracks and 16 vias.
It is built around the HLMP-EG30-QT000. Its parts include 4 resistors, 3 capacitors, 3 diodes, 2 connectors and 1 IC.
Main components
1README
README.mdExpaLight
ExpaLight is a red LED flashlight powered by a supercapacitor, designed especially for astronomical observations. The project originated for use during observation nights at summer astronomical schools at the observatory. Thanks to its robust and open-source design, ExpaLight is suitable for both amateur and professional users.
Technical Parameters
| Parameter | Value |
|---|---|
| Stored energy | 350 J |
| Light duration | ~10 h |
| Charging time | < 50 s (typ.), max. 2 min |
| Charging indication | Green LED off at 80% voltage |
| Charging interface | MicroUSB, ≤500 mA |
| Housing | 3D-printed PLA, durable, water-resistant |
| Light Source | High-efficiency red LED |
Key Features
- Supercapacitor energy storage (350 J)
- Light duration: up to 10 hours
- Fast charging: typically under 50 seconds, max. 2 minutes from full discharge
- Charging indication: green LED turns off at ~80% voltage
- Durable 3D-printed housing, mechanically and water resistant
- High-efficiency red LED, optimized for dark adaptation of the human eye
- No batteries needed, USB charging (microUSB)
- Open-source and repairable
ExpaLight remains an active project despite repository inactivity. The design was made to withstand years of usage.
Product manual – Czech version
Why red light?
Astronomers use red light because it preserves the dark adaptation of the human eye, making it ideal for observing the night sky.
Usage
- Can be placed horizontally (ideal for writing into observation logs)
- Can stand vertically with LED up or down
- Can be recharged while in use
- Works even when permanently connected to a charger
Maintenance
- Clean with cloth and mild soapy water
- Do not wash under running water or immerse in liquids
- Avoid abrasive tools to prevent scratching the housing
Frequently Asked Questions
Do I need to switch it off? No. The flashlight has no mechanical switch. It shines until fully discharged, then you recharge it via USB.
Why this shape? The hexagonal body prevents rolling, ensures stable positioning on surfaces, and supports versatile use (e.g. headlamp attachment in future).
Can I leave it charging permanently? Yes. The electronics are designed to handle permanent connection safely.
What happens if it is fully discharged? Nothing. Unlike battery-based lamps, the supercapacitor can be fully discharged without degradation.
Can I use a mobile charger? Yes. Any standard microUSB charger (5V, ≤500 mA) or USB port will work. Some smart chargers may fail due to low current draw — in that case, use another charger.
Availability
You can purchase ExpaLight at Tindie or contact us directly at sale@ust.cz.
Contributions
ExpaLight is an open-source hardware project. Suggestions and improvements are welcome! Please open an issue in the GitHub tracker.
Parts
15| Qty | Value | Footprint | References |
|---|---|---|---|
| 1 | 0 | Mlab_R:SMD-0805 | R1 |
| 1 | 100uF/6.3V | Mlab_C:TantalC_SizeC_Reflow | C2 |
| 1 | 10uF/10V | Mlab_R:SMD-0805 | C1 |
| 1 | 133k | Mlab_R:SMD-0805 | R4 |
| 1 | 270 | Mlab_R:SMD-0805 | R6 |
| 1 | 50F | Mlab_C:C_Radial_D18_L25_P7.5_BAT | C3 |
| 1 | 68 | Mlab_R:SMD-1206 | R5 |
| 1 | DER0705-3.3uH | Mlab_L:DER0705 | L1 |
| 1 | HLMP-EG30-QT000 | Mlab_Pin_Headers:Straight_1x02 | D2 |
| 1 | JUMP_3X2 | Mlab_Pin_Headers:Straight_2x03 | J1 |
| 1 | LOGO | graphics:UST_logo | G*** |
| 1 | LTC3625 | Mlab_IO:DFN-12-1EP_3x4mm_Pitch0.5mm | U1 |
| 1 | M4 | Mlab_D:SMA_Standard | D1 |
| 1 | MX-105017-0001 | Mlab_CON:uUSB-B | P1 |
| 1 | RED | Mlab_D:LED_1206 | D3 |
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Questions
How big is the CAPLIGHT01B PCB?
It measures 33 × 20.3 mm and has 2 copper layers, 1.6 mm thick.
What parts does the CAPLIGHT01B use?
15 parts, built around the HLMP-EG30-QT000. 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 CAPLIGHT01B KiCad files?
From the UniversalScientificTechnologies/ExpaLight repository on GitHub, at the commit this page was made from: the board is SCH_PCB/CAPLIGHT01B/CAPLIGHT01B.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the CAPLIGHT01B 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).