Cool Desk Lighting: A Homemade Cagelight

Cagelight in red flashing mode.
Cagelight on, in red flashing mode.

While panning absentmindedly through one of my dad’s farm/tools/random-outdoorsy catalogs, I saw something that really caught my eye: a cagelight that apparently was intended for use in a barn, but looked like it belonged in a mad scientist’s lab. It looked something like this: cagelight example

I immediately decided I needed to make my own version of the cagelight for use as an epic decoration for my mad-sciencey desk. I used some thick wire, LEDs and other electronics, 3D printed parts, and lots of hot glue. It turned out to look like this:

100_5011

This project consisted of two main parts: making a custom PCB to control the light, and designing an authentic cagelight enclosure. I ended up designing and 3D printing a custom case and using heavy gauge wire to make the cage.  Below is what it looks like lit up. It’s quite bright. Basically, a battery powers some white LEDs and some flashing red LEDs which can be switched on and off.

cageligt white light on
The cagelight on, in white-light mode.

Electronic Components and Making the PCB

Wiring schematic for the Cagelight.
Wiring schematic for the Cagelight.

The most challenging aspect of this project was designing the electronics to fit onto a circular PCB. The light has two different modes, either always on white light, or flashing red light. The flashing for the red light is generated by a 555 timer IC in astable mode that outputs a pulse at about 2Hz. The ‘mode’ of the light is determined by a three-way slide switch. When the switch is in its center position, it’s off, and if it’s in the right or left position, it’s in white-light mode and flashing red-light mode respectively.

I thought a lot about how to control the lighting before I opted to use the 555 timer. I had considered using an Arduino to control the flashing, and even using an actual lightbulb to be plugged into the wall. I even thought about getting a rotary switch and adding a whole bunch of color modes with more LEDs. I decided on a 9V battery powered circuit with the 555 timer and red and white LEDs for the sake of cost and simplicity.

Breadboard prototype of the cagelight electronics.
Breadboard prototype of the cagelight electronics. I ended up removing three of the red LEDs so that it would all fit on the PCB. Battery and switch are not attached.

I made a prototype on a breadboard first to verify that I choose the correct resistor values.

pcb cagelight non mirrored
This is my final hand drawn sketch of the PCB.

I then proceeded to design the layout of the PCB. I had one-sided 7.5cm blank etching board, so I decided to use the full size of the board by making the PCB  a 7.5cm diameter circle. I sketched and re-sketched the layout of the PCB on paper. It took me a good while to work out how to best connect it together, and I ended up using three jumper wires. After I sketched my final layout, I realized that I needed to mirror the layout because the components would be soldered to the other side of the board.

PCB3
As I started laying out the traces on the PCB, I realized that I needed to mirror my layout to take into account the fact that the components would be soldered on the opposite side of the board. I referenced this as I was laying the traces.

I laid the rub-on traces that came with the PCB etching kit after lightly sketching the layout of the circuit on the copper. This was by far the most time-consuming part of this project, and I had to constantly double-check and triple-check. I found quite a few errors.

Just about to start laying the traces!
Just about to start laying the traces!
The PCB ready to be cut into a circle right before etching.
The PCB ready to be cut into a circle right before etching.

After the tracings were laid, next I had to cut out the circular shape. I used my brother’s Dremel, with reasonably good, albeit exact, results. Finally I was ready to etch the board. Using a ‘safe’ mixture of vinegar, salt, and hydrogen peroxide, it took about three days for all the copper to be fully dissolved. I had to change the solution many times during the painfully slow process.

The PCB in a petri dish about to be bathed with chemicals.
The PCB in a petri dish about to be bathed with chemicals.
The PCB after etching and drilling. I added some Sharpied annotations.
The PCB after etching and drilling. I added some Sharpied annotations.

After all the copper was dissolved, I removed the black rub-on stickers with some steel wool to reveal a nice PCB! I then drilled holes and prepared to solder the components in place. Soldering the components was good fun, and the result was better than I expected. When the time came to test it out…it worked!

The PCB completely soldered together.
The soldered side of the finished PCB.
The component side of the finished PCB.
The component side of the finished PCB.

Here’s a list of the components used in the finished product:

  • 555 timer IC
  • 6x white 5mm LEDs (salvaged from an old flag pole light)
  • 6x red 5mm LEDs
  • 0.47uF capacitor (part of 555 timer circuit)
  • three-way slide switch (salvaged from old AM/FM boombox)
  • 1MΩ resistor (part of 555 timer circuit)
  • 330KΩ resistor (part of 555 timer circuit)
  • 3x 100KΩ resistors (for white LEDs)
  • 2x 47Ω resistors (for red LEDs)
  • 9V battery

    The PCB with the white LEDs lit up!
    The PCB with the white LEDs lit up!

3D Printed Case

Screenshot of the case.
Screenshot of the case. You can see where the PCB fits. I ended up printing it with white PLA.

After the PCB was finished, next was designing the case. I knew from the beginning that I wanted to use heavy gauge wire for the cage part, but I wasn’t sure how to make the ‘glass’ that would cover the PCB and diffuse the LED light. So I decided to make a 3D printed, thin walled,  case with white filament that would be translucent enough to let light through. I designed it so that the PCB would fit nicely inside the top of it, and so that the trimpiece/collar could be slid up around it.

Next was to make the trim, which would give it a place to store the battery, mount the switch, and attach it to the ceiling. I was originally going to make it out of metal, but after many literal sparks with the Dremel, it flopped.

This was a flop. It's actually the bottom of a bulk-size can of peanuts! It ended up being too small rough.
This was a flop. It’s actually the bottom of a bulk-size can of peanuts! It ended up being too small and rough.

So I opted to also design and 3D print the trim/collar piece as well, and it came out quite nice after I printed it with flexible black filament. I added a spot to mount the switch and holes to run the cage wire through later.

cagelight ss of tinkercad 3d design of trim part of case
This is the collar/trimpiece design for the cagelight.

Click here for more details on the 3D designs.

Assembly

All the parts before assembly. Not shown here are also little rectangles of metal that were folded and were glued in as mounting brackets.
All the parts before assembly. Not shown here are also little rectangles of metal that were folded and glued in as mounting brackets.

Assembling the cagelight was pretty trivial. I took some old heavy gauge wire (what they use in wiring houses), stripped it, and then bent it into shape. I used hot glue to attach all the parts together, and a little bit of solder to tack the cage wire in place on the outside.

The inside of the top, with everything in place.
The inside of the top, with everything in place.

From there, all I had to do was screw it up above my desk! It makes quite a nice decoration, and the white-light mode is bright too. The red-flashing mode makes a nice ‘do-not-disturb’ signal.

I’m happy with the results. I learned a few things about designing circuit boards, and I got to squirt hot glue all over stuff!

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