https://youtu.be/vnT8qnlGeMQ Here it is! I’m very pleased with the result. It’s hard to tell on a video because the candles are brighter than the dark painting so they over-expose the camera, but I think I’ve done a good job on simulating a flame. As time goes on I’ll experiment with assorted ideas for improving the…… Continue reading “Bearing Witness” 10: Done!
Candle flicker I wanted to achieve a candle effect. So it lit some candles and stared at them for a while. I mean I did some research… Three things about candle flames: Flickering = fading rapidly and non-linearly between brightness levels Flickers usually loosely follow a pattern, around an average brightness No two flickers are identical…… Continue reading “Bearing Witness” 9: Software
So, I have 1.2 metres of 2.5 cm right-angled aluminium on which to attach all the electronics. Step one: the candles: I bought a batch of 2.5mm nuts and bolts to attach the LEDs. There’s a washer behind the nut to spread the load where it meets the LED base, and a shake-proof washer by the head…… Continue reading “Bearing Witness” 8: Assembling the electronics
The original frame was of traditional construction. It consisted of four pieces of wood for the front, joined at 45 degree angles, and four pieces of wood for the edge, screwed to each other and to the front. What I needed to do was remove one of the edge pieces – the one at the bottom…… Continue reading “Bearing Witness” 7: Assembling the frame
Next, to get the ultrasonic range-finder working. The idea is to make the artwork interactive: the candles will glow until someone walks up to it, at which point it will begin a new sequence of bright flash / darkness / slow candle lighting. I bought this ultrasonic sensor on eBay for £1.63. It should allow the measurement…… Continue reading “Bearing Witness” 6: Ultrasonics
The Arduino For the previous project I used an Arduino Uno to control the LEDs. It worked fine, but it’s too large to fit inside the frame of this artwork. However, a little searching on the internet came up with the Arduino micro. It has all the same functionality as the Arduino Uno (with a few…… Continue reading “Bearing Witness” 5: Electronics
As described in the previous post, the heatsink for the Flash is only designed to keep the temperature at a safe level for a few minutes. Since the LED will only be lit for a few seconds every few minutes that’s all that’s needed. The problem is that if a problem occurs with the Arduino, such…… Continue reading “Bearing Witness” 4: Temperature check
COB LEDs get hot. It is true that they are more efficient than CFL lamps (compact fluorescents – the ones that take forever to warm up), and way more efficient than incandescents (either the old light bulbs or the hotter halogen bulbs). Even so, some 70% of the electrical energy going in comes out as…… Continue reading “Bearing Witness” 3: Cooling
The basic plan was to follow the previous project, using: An Arduino to control the effects 3 Watt LEDs to create the candle effect An ultrasonic distance finder to trigger the flash A 10 Watt LED to create the flash effect High powered Light Emitting Diodes (LEDs) High power LEDs are easy to use if you don’t run them…… Continue reading “Bearing Witness” 2: Constant current
My talented friend George Sfougaras created this artwork, Bearing Witness, in response to the terrible events at the Bataclan concert hall in Paris, on 13th November 2015. Unlike the previous artwork that I created lighting for, the shadows here are permanently present regardless of lighting. My challenge was to add light in a manner sympathetic to the artist’s…… Continue reading “Bearing Witness” 1: Design
