The second prototype for the Lys Bright project will incorporate four of the 1W LED beads, plus some additional changes. It measures 4.1 x 6.9 cm and costs $15 for five at Seeedstudio. I expect them to be here in a couple of weeks.
This time, some proper consideration for the thermal management is done. Although I did not intend more than three of these 1W LED beads, I tossed in another one, because why the hell not? They might run a little cooler at the same luminuous output as three LEDS, and the opportunity is there to blast all four for a short amount of time. The LEDs has a large thermal pad which will connect directly with the ground plane of the PCB on the top layer, and through a myriad of 0.3 mm thermal vias to the full ground plane on the bottom layer. There, a large exposed copper area can, and should, be mounted to a heat sink to absorb the 2-3 W of heat from the LEDs.
Other changes are
- The ability to connect external LEDs instead of the internal ones
- Hard on/off switch
- Connector for the ESP8266 wifi module or the HC-06 bluetooth module (optional, solder on the crystal for that)
- Connector for any external module which outputs an analogue or digital signal to the Lys Bright (still optional)
- JST connectors for battery and solar cell
And now I will direct my attention to the Heartbeat Logger project.