Vermes
Advanced Member level 4
The project started with a model on a contact board. Next was PCB. The whole device was self planned.
Then was the housing for LEDs. At first, it was planned to be an aluminum pipe and transformed solar lamps. The final choice was bamboo, because it's a cheap and easily available material with a hole inside, where the wires can be placed. Because the stairs were illuminated from outside, bamboo had to be protected against rot. It was made by brown wood lacquer.
The driver is located outside and covered with a layer of soil.
The driver in a tin.
The driver board.
The 'battlefield'.
A good idea for sensors was simple motion sensors. Usually their electronics work on about 8-10V, so it was necessary to change the board 220V into 8V and to plug the cable directly from the driver that provides 10V.
The sensor upstairs.
The sensor downstairs.
Description
The whole device is controlled by Atmega8. Although it has only 3PWM, mutliplexing had to be done. Each PWM canal powers 8 LEDs (23 stairs/LEDs). When lighting up, 3 next stairs which should be still dark, light a little. Most of LEDs are placed in bamboo, but few of them are placed on a concrete wall on the bend. The lightness is 20 000mcd and 60° angle. The sensors are simple motion detectors, they're excellent for this purpose and kept in a waterproof housings.
The PCB driver was made in thermal transfer method. A quartz is mounted to the board. The whole thing is powered by AC plug 12V 500mA.
In the pictures below there is a schema and PCB once again.
Program was written in C. It lights up and extinguishes one stair after another. In the future, the algorithm can be improved so it lights up one step 50%, another one starts to light. The stairs illuminate from the side where somebody comes. They extinguish from both ends to the center. This feature eliminates such problems as how the microcontroller can detect the situation when somebody turns in the middle of the stairs.
Link to original thread (with video) – Automatyczne podświetlane schody
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