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:


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.

Continue reading

My First PCB: Air Conditioning Fan

green light and fan pcb plugged in

As you may know, I enjoy making various personal air conditioning systems using old computer fans and the Arduino. In order to try making my first printed circuit board (PCB), I designed a personal air conditioning fan system that plugs into any standard USB port, and can be powered via computer USB or 5V wall adapter. Except for the printed circuit board etching kit my dad gave me for Christmas, pretty much every component I used was salvaged from old electronics (this is seriously low budget!).

usb fan circuit_schem

Basically, a fan is connected to and on-off switch to act as air conditioning. An RGB LED can be lit either green or blue, and a slide potentiometer both changes the color and adjusts the brightness.

parts to fan light circuit pcb copy
The parts used for the circuit.

Here’s the components I used, plus their sources:

  • Standard DC toy motor, from an old electric toothbrush
  • CA RGB LED, an old one that I had burnt the red lead out, so only the green and blue diodes worked
  • Black LED collar, from an indicator LED on an old computer tower (doesn’t do anything, just makes the RGB look cool)
  • 3-pin slide switch, from a broken ‘build your own plastic mechanical spider’ kit that my brother had
  • 3-pin slide 250K Ohm slide potentiometer, from an old space-age toy gun
  • 470 ohm resistor
  • USB-Type A to USB-Mini cable, from some old LeapFrog toy (I cut off one end and left only the Vcc and GND lines of the remaining wire)
  • 3D printed fan blades (I tested two different ones, and I’m working on designing my own)
My initial sketches for the layout of the board.
My initial sketches for the layout of the board.

I prototyped the circuit with a breadboard first, and then designed the PCB layout on paper, making it as space efficient as possible. Then I cut a 1×1 inch square (5×5 cm) from a larger piece of copper board, added the ‘wires’, or the black rub-on stickers that prevent parts of the copper surface of the board from being removed.

Partially etched PCB.
Partially etched PCB.

Next was to actually etch the board by putting into a solution. After doing some research, I found that you can use a mixture of vinegar, hydrogen peroxide, and salt, instead of the standard ferric chloride etching solution. Household chemicals are safer to use and won’t burn your skin if you spill it! I added equal parts vinegar and hydrogen peroxide, placed the board in the solution, and then sprinkled coarse salt on top.

Overall, it took about eight hours for all the excess copper to dissolve. I changed the solution twice, as the reaction slowed down as the solution dissolved the copper. The second time I added a higher concentration of vinegar, because it seemed to speed up the reaction more than the hydrogen peroxide or salt.

Some of the tools I used.
Some of the tools I used.

With the board etched, I used my dad’s drill press to drill holes for the components, and some steel wool to remove the black etching lines. Using my dad’s improvised soldering iron (a woodburning tool, a little high temp, but worked okay), I had my first experience soldering components to a board! The end result was decent, though it took me a long time to do it.

The two fan blades I tested out.
The two fan blades I tested out.

The last step was getting a fan blade for the DC motor. I printed two different fan models to test, and I’m working on my own right now. The green one below looks much fancier, but it moves significantly less air than the blue fan. It also has sharp edges, and I cut my fingers on the spinning blades more than once. I may print a scaled up version of the blue fan when I get the chance.

Prototype of my fan blade design made in Tinkercad.
Prototype of my fan blade design made in Tinkercad.
The finished circuit laid out.
The finished circuit board laid out.

Since the circuitry and parts have been gathered and put together, I now have to make some kind of case for the whole thing. Right now, the fan is practically unusable because the motor can’t stay upright. I could 3D design a case, make some kind of insulated wire stand, or make something with wood and cardboard.

Tech Tear Down – Dehumidifier PCBs

My mom is obsessed with dehumidifiers. When one of the three in the house stopped working (it was old and in bad shape when we got it, so it was no surprise that it broke) I of course jumped on the opportunity to tear it up, even though my mom was upset. It was already partially apart when I got it, because my dad had been trying to fix it. I was most interested in the two PCBs inside.dehumidifer_pcb_diagram

One was the control board, attached near the top of the unit, that you could adjust the dehumidifier settings, such as the on/off time, desired humidity level, and fan speed. Another PCB buried deep within served to connect the rest of the mechanical parts of the unit to power. There’s some relays, a large cylindrical electrolytic cap, an even larger ‘boxy’ cap, and a transistor with a heat sink.

dehumidifier pcb large capAnd finally, here’s a pic of my dog, Denver, next to the humidifier torn apart. The dehumidifier is medium sized as far as dehumidifiers go.

dehumdifier with denver

Tech Tear Down: Old Long-Buried 1980s Electronic Organ Guts

This is one of my strangest Tech Tear Downs yet… My dad, my brother, and I cleaned up our backyard, filling up a Bagster all the way to the top. We went through an old junk pile, and buried underneath everything and covered up with leaves and dirt was the electronic guts of an old electronic organ that we trashed sometime around 2007. I was of course extremely curious, and despite the dirt, I salvaged the bulk of the electronics to see what they we’re made of or course to see if there was anything useful.

TTD_organ_all four PCBs apart

Basically, there was four large PCBs stacked and bolted on top of each other. They consisted of diodes, transistors, resistors, and capacitors, as well as a few op amp ICs. Other than on the top layer, there was little corrosion on the components, and I wondered as to how useful they would be, considering that they’re from the 80s and they’ve been subject to very extreme temperatures, as well as water.

TTD_organ_the diodes

I was excited to see that there was loads and loads of diodes (the image above shows a section of one PCB after I removed a bunch of the diodes; they were easy to get to). I would estimate there was close to 80 silicon diodes that I could have used in a breadboard. I set a table and got out all my tools and spent a while removing the diodes and a few of the resistors, using mainly a small flat-head screw driver and needle-nosed pliers. I was able to get maybe 50 diodes, a few resistors, and a few transistors, as well as a few useless souvenir ICs.

TTD_organ_curvy copper connections

I tested a few of the diodes out, and they worked great. The transistors were junk, and most of the resistors had leads that were too short. But now I have enough diodes to make a decimal-to-binary converter!


Above is where I was working.

There’s a few differences I noted between these four giant PCBs and modern day ones. First, the etched copper connections were very curvy, instead of rectangular and crammed together as you see on modern machine-made PCBs. Secondly, the wires coming off the PCBs weren’t directly soldered onto the board. Instead, a little metal spike pokes out of the board and the wire wraps tightly around the spike, so the joint is more mechanical, as you can see in the picture below.

TTD_organ_wire spikes

Quite frankly, I don’t really know how these PCBs work inside the organ. They were labeled in a few spots as having something to do with ‘rhythm’ and there was a large mass of wires exiting the PCBs, so my guess is these boards were responsible for generating the different tones on the organ.

Tech Tear Down – Computer Mouse


1_computer mouse artsy PCB shot

I had the sudden urge the other day to tear apart another electronic device, the victim being the computer mouse that I use for my Raspberry Pi that happened to being lying so very innocently on my desk. The picture above is an ‘artsy’ flash shot of the inside of the mouse.

Taking it apart was easy. There was only one screw in the center of the undersided that I removed with my trusty old mini Phillips screwdriver. The bottom and the top plastic pieces easily came apart, revealing a PCB pressed into the bottom, connected to the wire coming out of the mouse. The PCB itself wasn’t attached with glue or screws, so it popped out easily.

2_computer mouse parts labeledYou can see the little red left and right click buttons in the image below. When you click the mouse, the plastic of the shell of the mouse hits the read button. It’s not plastic that makes the clicking noise when it hits the button, its the button itself that makes the noise. The scroll wheel has a third little red button under it that allows for the scroll wheel to click. In the middle, there’s a motion sensor that detects where the mouse is moving. Inside the black box on the right is a red LED, the ‘laser’ that lights up the bottom when the mouse is on. In addition there’s a multitude of caps and resistors.


In the images below, you can see the bottom of the PCB, and how it fits into the plastic casing. There’s a little transparent piece of plastic that goes under the PCB, and it helps focus the LED light. 3_computer mouse plastic casing4_computer mouse PCB in position


Tech Tear Down – Rechargeable Crank Flashlight

A crank flashlight is wonderful to have on hand; you never have to worry about the batteries. I have one that I use all the time. I decided to take it apart to see exactly hodiagram of flashlightw is functions, and there’s really quite a few things in there. The flashlight has one big button plus a crank you turn to charge it up. If you click the button once, all three LEDs light up, if you click it again just the center one lights up, and clicking it a third time shuts it off.

I started by remove four screws on the back to reveal the inside.

Inside, there’s a DC motor that connects to the crank shaft. When the crank is turned, the DC motor turns too, which generates a voltage, and the battery charges up. The push button, which is right in the middle of the PCB (printed circuit board), whidiagram of PCBch is the only input to the system. All of the capacitors, resistors, and diodes are used to control the process through which the LEDs cycle through the on and off cycle. I was interested in the four-legged integrated circuit (IC) in the middle. I’m used to seeing eight-legged ICs.

Next I removed the screws (circled in yellow in the above pic) holding the PCB to the black box. From there I could remove the clear plasticflashlight shell shell around the light, and pull the PCB away to reveal more screws that attached the whole chunk to the outside shell. There’s only three little LEDs that provide all the light given off by the flashlight!

Finally, I took apart the black box which contain the gear mechanism for the crank. The three gears are set up so that turning the top gear (connected to the crank shaft) slightly makegear mecs the bottom gear (connected to the motor) turn a lot. You can see there’s some slimely stuff that looks like petroleum jelly all over the gears to help the turn smoothly and quietly.

After I took it all apart, I put it back together using only my trusty little phillips screwdriver.