I saw these sunset lamps on the internet. They create a round circle of warm coloured light on the wall and are also used in photography. Of course you can just buy one, but then where would the learning and fun be? As you can see you can light up a wall or set an object in scene.

The advantage of making the lamp yourself is that all possible shapes and uses are limitless.

Actually, the trick is to install the led light behind a colour filter and a large lens, or simply dye the lens

So let's get started.

As always, these instructions are just the idea of how to achieve this cool effect. It's how you use it or build it in that makes DIY really interesting.

Supplies

1 white Led chip 1Watt or 3Watt
1 DC-DC step down converter. 3.3V fix or or adjustable. Model MP1584EN
1 aluminium piece as a cooling body
1self-adhesive copper tape, Conductive on one side only
thermal paste
epoxy resin
enclosure (i use 3mm MDF here)
1 Power switch
1 DC power socket
1 Power supply 5-20V
wires, glue, srews, nuts, tools,

Step 1: How Does It Work

This is as I understood it. In itself, the sunset lamp works like a projector spotlight.

The light that comes out of the led with a 120 degree beam angle is emitted almost straight via the second lens.

The small distance between the first and second lens creates a large spot of light on the wall or ceiling. You can play around with the distance, depending on whether you want a large or small spot.

Due to the shape of the large lens, chromatic aberrations occur at the edge. These are also intentional here because of the effect.

Step 2: The Design

I thought an octagon would look kind of cool. You can either put the lamps up individually or stack them.

So here is my idea how this could look like. I used the old Google Sketchup8 for the 3d drawing.

Then I created everything in Qcad in 2D.

The DXF file can be found here, so that everyone can adjust the design and size.

Spotlight.dxf
Download

Step 3: The Lens

Where to get the lens

You can buy a Plano convex lens, like the ones used in cars, or you can make your own.

I went with plan B because it gave me more control over the size of the lens and I always wanted to see if a resin lens would work :)

For the lens mould I used a silicone baking mould with semicircular balls of about 53mm.

Then I used a two-component transparent resin. The curing time for mine is 24 hours.

Resin is not as clear as a glass lens. But that doesn't make much difference with a 1W led and one advantage is that this one does not break.

I have mixed alcohol ink directly into the resin on some of them to see if the colour effect works. However, a colour film between the led and the lens works better.

Step 4: Led Electronic

A simple series resistor should not be used with high-power LEDs, as they heat up and the current then increases.

Normally, a constant current source is used for such LEDs. But since I didn't have one at home, I thought that a constant voltage source would also work.

These small DC-DC converters produce 1A in continuous operation without any problems. A 1W Led needs about 350mA, so everything is in the green area.

First connect the DC-DC converter to 5-20V and measure the output voltage at the converter. Set a voltage of 3.3V with the small timmer and only then connect it to the LED.

If everything has worked, the LED should now light up.

Always pay attention to the polarity when connecting.

Do not solder all the wires yet, as the electronic and the LED still have to be installed first.

Step 5: Led Cooling

The 1W Led is already available with small aluminium heat sinks. But if you only have the LED components themselves, you can simply use a small piece of 2mm thick 40x40mm aluminium, heat-conducting paste and self-adhesive copper tape, which is only conductive on one side. Fold the overhanging copper strip backwards, as the wires are soldered to the back side.

Mark the two drill holes.

Two holes drilled with 2.5mm and then a 3mm thread cut into them

Step 6: The Enclosure

The housing here is of course only an example. You can also use other objects or materials. Since I have a laser cutter, I decided to use 3mm MDF.

On the outside I used acrylic paint and transparent varnish.

After the paint has dried, the parts are glued and screwed together as shown in the photos.

If it is the version with the feet, do not forget to glue in the two 4mm nuts.

To prevent the light from shining through at the sides, simply inserted a piece of black cardboard to the edge of the front area.

I glued the lens into the front part with the correct diameter according to the size of the lens using epoxy glue. I haven't come up with anything better for fixing the lens yet.

Step 7: Installing the Electronics

Screw or plug the DC socket and the switch into the back part of the enclosure.

Now solder the DC socket and the switch to the converter according to the plan. Glue the DC-DC converter to the back cover of the lamp.

The converter output is soldered to the back of the aluminium sheet with the LED on the copper contacts. Now fix the aluminium sheet with two M3 screws.

Connect the power source and test it before assembling the rest of the lamp.