I want a flashlight that can cure multiple wavelength resins without having to worry about what it requires.
Resin Curing wavelengths
- 365nm – Fluorescence, inspection, optical adhesives
- 385nm – Industrial adhesives, coatings, dental
- 395nm – hobby resins
- 405nm – 3d resin printing
I chose 365, 385 and 395. I already have a high power 365nm with a zwb2 filter for Fluorescence so this light will mostly be for curing.
Testing
Now onto testing. I need to test so I know if these different LEDs could work in parallel. The datasheet wasn’t clear enough to read so I need to collect my own data. I purchased 2 LEDs to replace the 2 that come with the Convoy S12 UV LED light.
To test, I set the current limit and measured the voltage of each LED. I find that the values are very different per wavelength I do not think parallel will work. I will need to buy a boost driver.
LEDs Tested:
| PN | wavelength | |
| CUN66A1G | 365nm |  |
| SST-10-UV-A130-H385-00 | 385nm |  |
| CUN96A1 | 395nm | |
Current – Voltage chart
| mA | Seoul 365nm (V) | SST-10 385nm (V) | Seoul 395nm (V) |
| 50 | 3.265 | 3.084 | 3.022 |
| 100 | 3.334 | 3.137 | 3.069 |
| 200 | 3.417 | 3.207 | 3.132 |
| 300 | 3.472 | 3.267 | 3.178 |
| 400 | 3.518 | 3.312 | 3.212 |
| 500 | 3.556 | 3.356 | 3.239 |
| 600 | 3.582 | 3.390 | 3.260 |
| 700 | 3.610 | 3.423 | 3.281 |
| 800 | 3.637 | 3.456 | 3.301 |
| 900 | 3.661 | 3.485 | 3.317 |
| 1000 | 3.684 | 3.512 | 3.333 |
This shows clearly that a parallel circuit would NOT be good for this flashlight. Even slight variances of voltage will cause LEDs to be current imbalanced.
Parallel @ 1.0 A total
At the 1 A total operating point:
- Shared voltage ≈ 3.269 V
Branch currents:
- Seoul 365 nm: 52.2 mA
- SST-10 385 nm: 304.2 mA
- Seoul 395 nm: 643.6 mA
Power:
- Seoul 365 nm: 3.269 V × 0.0522 A = 0.171 W
- SST-10 385 nm: 3.269 V × 0.3042 A = 0.994 W
- Seoul 395 nm: 3.269 V × 0.6436 A = 2.104 W
Total parallel power: 3.269 W
Power share:
- 365 nm: 5.2%
- 385 nm: 30.4%
- 395 nm: 64.4%
Series
By wiring in series, the difference in power usage between them is much more evenly distributed.
Power comparison
Series @ 333 mA per LED
- Seoul 365 nm: 3.488 V × 0.333 A = 1.163 W
- SST-10 385 nm: 3.283 V × 0.333 A = 1.094 W
- Seoul 395 nm: 3.190 V × 0.333 A = 1.063 W
Total series power: 3.321 W
Power share:
- 365 nm: 35.0%
- 385 nm: 32.9%
- 395 nm: 32.0%
Assembly
Here is the MCPCB with the 3 LEDs soldered. I converted it to a Series PCB by cutting the copper along the lines shown.
