handicraft – Simon Geldner

Firewood Lamp

Simon — Fri, 28 Feb 2014 15:54:00 +0000

Sometimes, pieces of firewood look really good. You may just place it somewhere as a very simple decorative elements with this certain touch of nature. Now, why not placing a hidden (or at least semi-hidden) LED-stripe inside, which illuminates the room with warm, indirect light?

So, that I did. The other firewood piece with the heart, formed a white threat and a couple of nails was just another idea of what you can do with firewood.

2-step PWM dimmer

Simon — Thu, 19 Dec 2013 09:08:24 +0000

When we renovated our living room, we bought new lights for the walls that should make a nice, warm room-illumination and furthermore make any kind of ceiling light redundant. We bought these online, and had to realise that they looked good, but were way to bright. I told my dad, that I would fix this.

So I researched a little and spend hours looking for existing plug-n-play solutions. I found some, but not a single one was small enough to fit inside these lights, which indeed had very limited space. So I set out to solder my own circuit board, embedding a cheap PIC microcontroller which would pulse the LEDs through a transistor. You can see my very plain circuit design in the image.

So what the microcontroller does, is that it uses PWM (pulse width modulation) to turn the LEDs on an off 16.000 times per second. By changing the pulse width, i.e. how long in every cycle the LEDs are on respectively off, the perceived brightness can be changed. E.g. if the LED is turned on 10% (and 90% off) in each cycle, it is obviously darker than when it is turned on 50%.

As I was now dealing with some basic embedded programming anyway, I thought I could at least allow us to dim the light in 2 steps. This would bring the comfort of having a nicely dimmed illumination as a normal state, but still give the option of having more light when needed (we use the latter quite seldom, but then it is very appreciated). How this works: The microcontroller has a small non-volatile memory, the so-called EPROM. Now when the light is turned on, the microcontroller gets power and goes through some “start-code”, that is only executed once after power up, I set a certain bit in the memory to 1. After a countdown of three seconds, I reset the variable to 0. If, and only if, the light is turned off within these three seconds, the microcontroller turns off and cannot reset the variable. This in return means, that the next time the light is turned on, this bit is still set to 1 and not as usual to 0.

So, the first thing I do when the microcontroller starts, is to read that bit. Does it say 0, I activate a dimmed light. Is it set to 1 (because the light was switched on and then off within three seconds before), I light the room up a little more.

It reads easy, but it was a struggle. Furthermore, I had to do it for all three lamps…

The circuit board:

before:

After: (this is another lamp in the same room).

Gallows Lamp

Simon — Fri, 18 Oct 2013 21:31:13 +0000

I suddenly had this idea of hanging a lamp on the gallons. I wrote the idea down and during the following days kept coming back to it. First, I wanted a lightbulb to be really hanging, however then it would have had to be rather big. Then I altered the idea to the final implementation: A fixed spotlight shining down, illuminating a small object. I bought some decorative gravel-like stones. The objects changed over time. It was placed in my parent’s hallway and guests always acted a little irritated, which was part of the initial idea – isn’t this what they call art?

Another lamp

Simon — Thu, 23 May 2013 17:40:34 +0000

Another lamp. LED-based.

Tower Lamp

Simon — Sun, 21 Apr 2013 21:48:38 +0000

The illumination is coming from the bottom, where a couple of yellow LEDs are soldered together and somehow evenly distributed. Above them, there is a thin layer of acrylic glass, which, to diffuse the light, is covered with a diffuser foil. On top of that, several small pieces of wood are glued on top of each other. The wood was beforehand brushed with brown and then white colour. Then parts of the white colour were taken away with a rough sandpaper to give the wood a used-look.