Live-edge oak spotlight light fixture - part 2 - adding ambience

In my previous post, I built a hanging light fitting of live-edge oak and recessed GU10 spotlights.

There is actually more to the project.

Sometimes, spotlights can be a bit overpowering, and it's preferable to have some ambient, indirect light.

During construction, I had the idea of creating this light in a way that would allow use of the spotlights, an ambient light, or both.

To create the ambient light, I used LED strips on the reverse (upward-facing) side, to reflect light off the ceiling.

I cut some thin strips of oak with a 45-degree angle and mounted them in a rectangle on the back - angled side outward, to help direct the light. An RGB LED strip was mounted all around this.

Control

I initially thought of using the LED driver that tends to come standard with rolls of LED strip, but as the existing wiring leads to only one switch, without some rewiring through the ceilings/walls, it would be limited to either having both the spotlights and the ambient light on, or just the spotlights on without the ambient light - it would not be possible to have the ambient light on without the spotlights.

In order to combat this, and to lay groundwork for a potential future project, I included a solid-state relay and an Arduino. The arduino would drive TIP31 transistors to drive the 3 channels for the LEDs red, green and blue, and additionally control a solid state relay which would act as the switch for the spotlights.

The idea would then be that the light switch would remain on, more like a utility switch, and then all control of the light fitting would be handed over to the Arduino.

 

Power

 

The original wiring sketch.
it's just a rough sketch,
not a proper wiring diagram.

 

The LED strips take 12V, and the microcontroller takes 5V, so a PSU is needed to bring the power down to usable levels.

For this I used an old net-book power supply. This was wired into the back of the light fitting. Caution is needed to make sure that nothing too powerful is used, as typically a houses' lighting circuit breaker is tripped at a much lower current than the mains sockets.

 

Revised to include the additional components

This would normally be plugged into a wall socket, where it's plug would have a fuse. However in order to wire this into the lighting wiring, the plug would need to be removed - obviously this introduces a safety concern. To ensure that this would still be fused, I replaced the wall switch for the light to one that includes a fuse, ensuring that the light is behind the fuse.

 

Communication

To communicate with the Arduino, I used a cheap HC-05 bluetooth to serial adapter, the same as I've used in other projects like the Bluetooth Macro keyboard app.

The arduino receives 4 bytes, followed by newline characters. These correspond to 1 byte each for the red, green and blue channels in the LED strip, and the final byte is either a simple 0 or 1 to indicate if the spotlights should be on.

For now this is sent by pairing with my phone and using a bluetooth serial terminal app from the Google play store. I'll probably create a more custom app in future, but for proving the concept, this works just fine.

 

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Live-edge oak spotlight light fixture

The basic idea

The idea is that the fitting uses GU10 spotlight fittings like those typically recessed into ceilings.

However, instead of recessing them into the ceiling, they're recessed into a piece of live-edge wood, which is hung from the ceiling like a more traditional light fitting.

The woodwork

There's not much really in the way of woodwork in this project, just clean off bark and splintery bits from the live edge, preserving as much of the edge as possible.

Quite a bit of sanding was also needed to clear up the surfaces.

The end of the board I had was cleanly sawn which I thought detracted from the live edges, so I broke the corners down with a carving disc on an angle grinder.

Creating grooves for
the spotlights latches

Then measure the centre line. I started by taking the average width of the board and working from that, but there is some leeway - having both sides be live edge makes this near impossible to find a perfect centre line, but ultimately as long as it looks central to the naked eye.

The spotlight fittings are not designed to go through the thickness of the board - after all, they're intended for plasterboard ceilings. While it won't affect the functioning of the light, it means that the spring loaded clips that latch. To work around this, I used a forstner drill to thin around the edge of the spotlight holes where the latch would sit - This is easier to do before the main spotlight hole is cut out, to stop the forstner bit from slipping.

Then I cut out the holes for the spotlights by drilling a pilot hole and widening with a jigsaw.

Test fit of one of the light surrounds

Wiring the spotlights

The three spotlights are wired in parallel, split across 2 junction boxes. Having them in parallel means that if one bulb was to fail, the others could continue to function.

 

To make installing the light easier, the lead that connects from the ceiling to the wood itself included a 'kettle plug' style plug and socket, simply so that the wiring could be done on the workbench, and just plugged in at the time of installation.

 

Mounting

The ceiling roses were purchased, and have simple hooks on them for hanging the chain.

Eyelet screws were attached in the back of the wood at each corner, from which the chain was attached.

Enough leeway was given on the chains so that adjustment could be made to ensure that the light hangs flat.

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