I recently gained access to a Formlabs Form 2 resin 3d printer. Since resin prints are extremely smooth and accurate, I decided to build a Qi wireless charger. The charger I imagined would react to the phone charging with leds. Since I have became comfortable with 3d printing, I decided to challenge my abilities by not using a micro controller for the reactive lights. I had very little knowledge about circuits and learned a ton throughout the build process.
Please pardon any mistakes made throughout the document. It is currently finals week. I will fix any mistakes that come to my attention asap.
Step 1: The Model
The charging case was designed in Autodesk Fusion 360 to be printed on the Form 2. The Form 2 is incredibly accurate. Because of this, the parts are very precise and may have to be altered if used on a fused deposition modeling printer (FDM).
The top and bottom plates were designed to be printed with Formlab's gray resin and the center ring was printed with Formlab's clear resin.
Step 2: Printing
Printing is very straightforward. The Form 2 rarely fails and can be left unattended for long periods of time. To prevent resin from building up and hardening on flat surfaces, all parts are printed at an angle. When the print is done and cured, the supports snap off easily. A little sanding and polishing with mineral will perfect the high quality models. All parts pictured here are raw and have not been finished. Despite a few marks on the surface, the print comes out of the printer in fabulous condition. The pieces snap together well and fit snugly.
Important note: The wall on the base plate of the model not fail during the print but could not withstand the wear and tear from the build process.
Step 3: Electronics
The most important part of the build is the wireless charger. I bought my circuit board on ebay. There are three important qualities to look for when choosing a charging board:
- The charger should be Qi compatible. Qi is an almost universal standard for wireless charging and should charge most phones with wireless capabilities.
- Three coils are way better than one. Most cheap wireless chargers only have one wire coil to transmit electromagnetic energy to the phone. These tend to take much longer to charge and have a much smaller field which the phone must align to.
- A charging indication light. When the phone is charging on the coils, an indicator light toggles. The charging indication currents will be used later in the project to turn the LED charging lights on and off.
The charging circuit runs off of 5 volts while the LED strip will run off of five. In order to use both, I purchased a converter that stepped a 12 volt input current down to 5 volts. The converter's housing was bigger than the specifications stated so I had to remove the plastic case leaving the waterproofing circuit epoxy exposed.
A 12 volt blue led strip will be used for the visual reactive lights. The strip should be small enough to fit inside the gap provided by the clear center ring of the print.
Other electric components that I used in my reactive glow circuit were, Capacitors, Transistors, Resistors, Relays, PCB prototype boards, and variable resistors.
Step 4: Relay/Transistor
My charging circuit has two led indication lights. When there isn't a phone charging, a 1.3v current will light up a red led. When there is a phone charging, the current will jump to 3v causing a blue led to alight. This works perfectly for me since transistors can act as switches at similar current levels. In order to provide an auditory cue to signal the phone charging, I also wanted to add in a relay. Relays project a nice "click" when currents are engaged or disengaged. In order to operate everything, I created a very unusual circuit that drew from both the indication circuit and the 12v power source.
Since the indication current varies, I was able to attach the relay design directly to the positive and negative terminals. However, I did find that on my particular circuit the positive and negative labels were backwards.
Step 5: Led Circuit
As I mentioned earlier. I have zero experience with circuits so the one I created here is not the best example. This led fader circuit is very simple and is used to minimize the harshness of the off/on transition. When power is applied, the lights quickly fade on. However, once power is disengaged, the leds slowly fade off resulting in a cool effect.
Once I was happy with the circuit, I soldered it onto a PCB board. After testing to make sure it was working properly, I used a box cutter to cut the PCB down to size.
I am already working on a cooler circuit that can do more without the use of an Arduino.
Step 6: Assembly
Once all the circuits are connected assembly is very simple. The only hard part is getting all of the electronic components to fit inside the case like a jigsaw puzzle. The charging coils snapped perfectly into their designated slot. I did have to drill a hole though one of the walls in order to supply power to the led strip which I wrapped around the parameter. Just to be safe, I covered all exposed electronic connections on the circuit boards which could potentially short circuit. The 12v power supply perfectly fits through a hole in the back and is snug enough to not require glue. Once everything was tested, glue all components to the housing case to prevent shifting.
Step 7: Final Product
And the charger works! Im extremely happy with how this charger looks and cant wait to share more about it. As I mentioned earlier I am swamped in the middle of finals so please check back for some additions (better photos and videos).
I am currently working on a second part to this instructables where I redo the circuit in order to make the leds act even cooler.
Step 8: CAD Models
All three STL models are in inches.