I started this project over a year ago because I felt I could do a better job than the original makers. Here I put before you version 3.2. If you're curious about version 1 here is a link to my original instructable: https://www.instructables.com/id/DIY-Power-Adapter..
My second version was made of through-hole components and was just not what I envisioned as being "better". My third version was made on a custom fabricated PCB and used mostly surface mount components. I'm quite happy with the way its turned out, but I am always looking to make it better. I've been debating on making it even smaller with the use of some Texas Instrument power ICs so stay tuned for the cool things to come! I'm always open to feedback and improvements you think would make this better. I'm currently selling both pre-built versions and DIY kits so please do message me if you're interested!
Like always please read the entire instructable before you begin such a project! It just might save your butt in the long run haha.
Step 1: Parts & Tools
Heres a list of the parts you'll need along with the tools that will make this DIY project a breeze to put together. If you've ordered a kit from me then you will have all the parts listed below; the tools are what you'll need to provide yourself.
2x 470 Ohm 1206 Resistors
1x Green LED 1206
1x Blue LED 1206
4x 22uf 16V C Type Tantalum Capacitor
5x 100uf 16V B Type (3528) Tantalum Capacitor
1x DC 5.5mm x 2.1mm Female Barrel Jack Pigtail
1x Quad 2 Input Nor Gate 14-PIN IC
1x 10k Ohm Potentiometer
1x Panel Momentary Tactile Push Button 6mm x 6mm x 7mm
1x DC-DC High Wattage Buck Converter
1x AC-DC 12V 3A Wall Wart
1x 3D Printed Power Tip
1x Framing Nail ~4in
1x 2ft 20 AWG Balck Wire
1x 550 Paracord
- Medium/Small D Tip
- Small C Tip
Solder Flux (optional but recommended)
Liquid Electrical Tape (optional, but highly recommended)
45 Degree Snips (any snips will work)
Multimeter to verify voltages and check to ensure nothing is connected that shouldn't be!
Super glue, gel type is preferred
Step 2: Step 1: LEDs & Resistors
You may have noticed I started with the IC first, I DO NOT RECOMMEND THIS, you'll understand later. Soldering the led and the resistor should be easy as cake. Put some solder on the pad and move either the LED or the resistor in place and tack one side down. Then you can move onto the other side. The resistors have no orientation, but the LEDs do! Observe the pictures for guidance. In my pictures, the green dot on the top signifies the negative terminal.
For my boards: R2 and R3 have a 470 Ohm resistor. R1 is if you do not want to use the potentiometer to vary the voltage and you want a set voltage.
Step 3: Step 2: SMD Capacitors
The capacitors needed for the buck converter are placed in parallel to get an equivalent of ~580uf. The math said it was right, but in reality, it didn't quite measure out to that, hey close enough. Probably in the next version I'll fix this to make it more accurate.
Start with the large SMD capacitors by placing a blob of solder on one side and tacking down one side of the capacitor then the other side.
Then move onto the smaller capacitors following the same guidelines as above.
Step 4: Step 3: Through-Hole Components
Insert the round peg into the round hole... it's quite simple here. No worries if your new, we've all been there. solder flux is your friend if you messed up. Follow the pictures and you'll be dandy. Make sure to snip those sharp edges and leftover leads.
Right now would be a good time to use the isopropyl alcohol to clean up any solder residue and flux on the board.
Step 5: Step 4: Wire
Measure out 2 20 AWG cables less than 12 in long. Solder the two cables to the two pads labeled +/- output. Once the two cables are soldered, add a large amount of solder on the back where there is a large exposed pad. Be careful you do not bridge the two pins that are not part of the large solder pad. See the picture for reference!
Add the female barrel jack connector during this time, follow the pictures for guidance. Quick note, I removed some length of the exposed wire and shortened it.
Step 6: Step 5: IC
The was my original first step, but due to issues with the IC overheating, I recommend doing this as the 5th step!!! Before you solder the whole chip down you will need to test your DC-DC buck converter to ensure the inhibit pin is a high or low inhibit. Now for my case, the chip I originally had was a low inhibit and this matched the data sheet. Unfortunately, when I purchased a bulk amount they ended up being a inhibit high so I had to make some on the spot changes.
BEFORE you solder this chip, ensure you do not heat the chip past 260 degrees centigrade more than a few seconds otherwise you will destroy the chip. I highly recommend you lower your soldering iron temperature and let the chip cool every few pins you solder. You'll find out if you destroyed the chip a little bit later when we do some testing.
If you've bought a kit from me I've already tested the buck converter and made the modifications to the NOR gate IC.
If you are building this on your own and you find that you are an inhibit high, then you will remove Pin 3, Pin 10, and Pin 11. You will need to bridge Pad 2 and Pad 3 together (see the picture).
We need to test everything before we solder the buck converter and can no longer access the SMD components.
Grab your safety goggles, seriously, these capacitors rupture violently. Now you should note that if the IC has been overheated a few of the 100uf (the black ones) capacitors will explode. No worries though, if this does happen you will need to remove the black capacitors and only the black capacitors, including the unexploded ones because they could be shorted (you do not need to remove the yellow capacitors 22uf). You also need to remove the NOR gate IC. You'll need to find either new ones to replace or contact me and I can send some more. Make sure to clean the board with the isopropyl alcohol and a Q-tip to clean up all the flux and if the board had any exploded part residue on it.
Step 7: Step 6: Power Board
This can be a little difficult. I initially designed the board so that the buck converter would fit right on top of the male pins, but the pins on the buck converter were very difficult to remove so I went with this option instead.
The buck converter pins will form a 90-degree angle with the pins on the board. I tried bending the last pins in each set in order to "lock in" the buck converter so it wouldn't move while soldering it. I highly recommend adding solder flux to the connections; it will make the soldering experience much less frustrating. Once soldered, snip the excess pins.
Step 8: Step 7: Sleeving (Optional)
If you are interested in sleeving the cables now is the time. If you're not interested, feel free to skip ahead.
The first step is to cut a piece of 550 paracord that is approximately an inch longer than the cable you have already cut. The de-core the paracord and slide it over the cable; here you may need to use the inchworm technique. Once the cable is set, cut a piece of heat shrink to your desired length and slide it over the sleeving. I do not recall the diameter of the heat shrink, but I did cut mine till it was about 1/4 of an inch long. You can either heat shrink the other end or modify the 3D printed battery casing so that you can hide the heat shrink in it.
Step 9: Step 8: Power Test
This should be a great moment for you! You can now plug in the device and test it. You will need to adjust the 10k Ohm potentiometer while pressing the button to see the voltage change from min 1.2 volts to max 1.8 volts. See the pictures for reference.
Step 10: Step 9: 3D Printed Battery Case
You will need to cut the wood nail you've acquired. The nail head will need to be cut till its about 35-36mm long, then the remaining nail will be cut down to a 30mm segment. The remaining nail can be recycled. Grind off the burrs and grind the top of the nail head so you have somewhere to solder. Grind the nail head so that the head looks more like a D, this will help later with spacing.
Turn your iron up as you'll need the heat. Apply solder flux to the top of the nail head and apply some solder until it sticks. Attach the positive wire to the middle rod and the negative wire to the smooth rod. Do the same for the other segment of the nail, but keep in mind that you will need to solder to the top of the nail otherwise it will not fit into the case!
Apply some liquid electrical tape to the top of the smooth nail around the solder joint and a few mm below. Reason for this is that the nail head and the smooth nail come uncomfortably close together. Better though it to grind down a portion of the nail head... I'll add that to the top.
Everything should fit perfectly in the casing, apply some superglue and make sure the rods stick.
Printing the Battery Case:
NOTE: The attached stl may not have a deep enough grove for some models and may require some slight modifications. I recommend a dry fit first and if the rod protrudes too much, scrape out some of the plastic in the print until it fits like a glove!
I'm currently selling assembled versions of these if you would like to buy them. Otherwise, the stl files are attached. I used a Stratasys Mojo to print mine. I cannot say how these will print with other 3D printers.
Step 11: Step 10: Final Touch
This is where you will apply the liquid electrical tape to various portions of the board for your safety and the well being of the board.
- The +/- input power pads where the barrel jack connector is located.
- The +/- output power pads where the two 20 AWG cables are connected.
- The bottom of the +/- output power pads, see picture for reference.
- The connection between the buck converter and the male pin headers.