A project conceived by Barbara Cidral for her bachelor degree in Product Design. She’s been researching lighting systems that takes in account the effects of blue light in the body melatonine production. The proposed solution is a lamp that changes it’s hue through the day.
It’s good to mention that this is the second lamp that we worked together. The first lamp was also a Cicardian lamp, but the capacitive sensor were implemented more in the software side rather than using a specialized integraded circuit.
- A Dimmable lamp;
- No buttons, only touch control;
- light hue changes through the day;
- … and everything in a 2 week deadline;
The dimmable and dynamic hue requirements was solved using a microcontroler with PWM outpus. The system is a prototype, so no optimization in price/performance was needed – an arduino would solve of the problem. Concerned about dimensions, we prototyped using an arduino pro micro.
For a more reliable time source, we used a Real Time Clock module, with I2C interface.
The touch interface was made by a capacitive sensor  assembled in a simple pcb module. As mentioned before, in a past project the capacitive sensor implementation was almost entirely programmed in the software side, which gave us a lot of freedom in threesholding, detection and debouncing aspects, but also complicated things a lot.
So, choosing a specialized chip with a lot of inputs and easy configuration was a really good option.
The LED driving system were simple current sources using discrete components [fig 1].
And the LEDS used were:
- 1x 23000k LEDs 10W;
- 1x 3000k LEDs 10W;
- 3x 20000k LEDs 3W;
- 3x 3000k LEDs 3W;
The 10W LEDs were pointed to the ceiling, and all the others are distributed in the structure, creating an “indirect” light source.
In the first integration testes we used a Perfboard, but later we made a PCB for a better finishing.
 MRP121 datasheet