I first saw similar projects on DIY Perks, and figured it would be cool to have a giant flashlight around. After building it, I realized it is much more useful than I originally thought. I have used this at summer camps, and outdoors a lot. Using this flashlight is so much better than a smaller flashlight, because it lights up the path almost like daytime - no more need to strain your eyes to see where you will step. Unfortunately, I do not have any pictures of this being built.
The parts in this flashlight are commonly available (at least for people like me). I used a 100W cool white LED, 2 80mm computer fans as well as a spare CPU heat sink to cool it, a 150W boost converter to power it - the LED needs around 30V to operate - and an LM2596 buck converter to power the fans with around 10V so that they operate quietly. For all the high power wiring, I used some 18AWG wire from an old AC cord. I replaced the potentiometer on the boost converter, and mounted a regular, single-turn potentiometer to the case.
To power this beast of an LED, I used a small LiPo battery. I mounted it outside the case, as there was not room for inside while still allowing airflow (I also didn't want to permanently mount it anywhere). It's only 1000mah, so it does not last long under a 100W load. The main consideration for the battery is that it must be able to supply 100W continuously. I also made an 4S4P 8000mah Li-ion battery from recycled 18650 laptop cells to power this, and it lasts a lot longer, but it also about 10 times heavier - not ideal for a handheld flashlight. I also added a 1-8S low voltage alarm to keep from draining the batteries too low.
Building a custom case
For the case, I used 3mm MDF board, and cut it out by hand with a saw, all 4 sides individually. After mounting everything to the sides with M3 screws and some hot glue, I attached the 4 sides together using angle brackets and bent strips of galvanic steel strapping (to act as angle brackets). The handle was made from a piece of an old DVD drive case, cut off with a rotary tool, and bent to shape by hand with the help of a few pairs of pliers. Overall, it looks pretty good, and has a sort of steampunk aesthetic.
The next version of this flashlight will be contained within a large PVC tube, which will be much more durable than the 3mm MDF construction that I built this time. The battery will also be contained inside the unit, but ideally still be removable.
One thing to be aware of with these cheap 100W LEDs is that the LEDs are not perfectly matched. This will have the effect of some LEDs getting much more current passed through them than others, which could be dangerous and lead to fires or explosions. Use them are your own risk. There are lots of people using these LEDs and have not had a problem, but just be aware that it can happen. The best way to check your specific LED is to power it from as low of a voltage as possible - until the LEDs just start to light up. If you see that some of the LEDs are much brighter than others, it might be a good idea just to keep an eye on them, and check it periodically. Just on be on the safe side, I set the maximum voltage on the boost converter to around 31V. The max voltage for these 100W LEDs is around 33-34V, so I am not driving it as hard as I can, which does allow some headroom for unmatched LEDs.
Project by: Micah Black
Written By: Micah Black
I've wanted to make an Arduino on a breadboard for a while now, and finally found some time to do it. My Computer Engineering class at school will be making and using this kit, that I am selling here, to build their own Arduinos, and then make some cool projects with them. For me, this was a pretty straightforward project (except for an invisible 1 on a capacitor that gave me a fair bit of frustration when trying to burn the bootloader), but required a lot of time and learning some new skills - PCB design.
Creating the schematic
The first step was to create a schematic. Using the official Arduino schematic, Arduino's version of a breadboard / standalone Arduino, and a simplified version of the schematic that I found online, as references, I created my own schematic for the Arduino using EasyEDA. I wanted to keep all of the components through-hole components so that it is easy even for beginners to solder it (for the PCB version), and it fits in breadboards. Given that condition, I had to forego a built-in USB to serial converter because all the ones I could find were SMD components (if you know of a TH USB-serial converter, let me know). I am using an external USB-Serial converter to program it.
Wiring it all up
All the wiring was pretty simple, and just requires following the schematics. There are very few jumper connections required to make the Arduino function, but more if you add all the regulators, LEDs, and resistors, there is a bit more wiring.
Burning the Bootloader
Once all the components were correctly connected, all the I had to do was to burn the bootloader. The easiest way that I found to do this is to use the excellent program written by Nick Gammon that can be found here. A fully working Arduino is needed to connect to the ATMega328 chip, and will burn the bootloader to it very easily.
First program - blink!
After the bootloader is on the chip, uploading the first program is as easy as plugging it in, and pressing upload. The classis blink sketch is an easy test program to upload. Once it resets, the LED should start blinking at 1 second intervals.
Designing the PCB with EasyEDA
Once I confirmed that everything was working, I started making it in to a PCB using EasyEDA. I arranged all the components on the board, using the Arduino shield template on EasyEDA as the board outline. Once arranged, I used the autorouter to make all the traces. After looking over the board, I could see a few issues that I fixed manually, and then ordered my first batch of 10 PCBs through JLCPCB (amazing prices by the way).
PTC Fuse and USB Port
After assembling the first prototype board and using it for a while, I found it really annoying that there was not a USB port onboard, so it was harder to power. Back EasyEDA again to add a though-hole mini USB port, and accompanying PTC fuse to the circuit, which will protect against drawing too much current from USB ports.
You can buy the Arduino as a kit from us here. If you want to build your own Arduino, while learning a little more about all the components required for it, and practicing your soldering skills, this is an amazing project. Once completed, it is exactly the same as a regular Arduino, with an external USB to Serial adapter.
Project by: Micah Black
Written By: Micah Black
For the past year or so, I have been collecting laptop batteries and processing and sorting the 18650 cells inside. My laptop is getting old now, with a 2dn gen i7, it eats power, so I needed something to charge it on the go, though carrying this battery around is definitely not ideal. Now that I've made it, I also use it a ton to power my soldering iron, a hakko T12 clone kit from Aliexpress. I rarely use the computer power supply on my workbench anymore, and just use this 4S 10P battery.
Selecting the Cells
All the cells I used in this battery have been tested in my 76 cell charging and testing station. This was the first pack I made, so I used red Sanyo cells in the 1900-2000mah range to save the better cells for other projects coming up - I'm thinking an e-bike and small powerwall or portable power station. This pack is 4S 10P, 40 cells in total.
Making and Adding Bus Bars
The bus bars for this pack are made from 4 pieces of 20AWG wire from old Christmas lights, twisted together with a clamp and a cordless drill. I made three rectangles to connect the cells in series, and two straight bus bars for the positive and negative connections.
Tinning the Cells
After putting all the batteries into 4 4x5 cell holders, 2 on top and 2 on bottom, I used a flux pen to add flux to all the cells. Soldering to 18650 cells is perfectly fine, as long is it is done quickly. Don't hold the soldering iron on the cells for more than 2 or 3 seconds. I use a 60W Nexxtech soldering iron. It takes almost 10 minutes to heat up, but it works great. Just add a small dot of solder on both end of each cell.
Fusing the Cells
I used 2A Glass Axial fuses on all the positive ends of the cells to connect to the bus bars. Given that these are not amazing cells, 2A each might be pushing them, but 1A fuses would be enough. I need this battery to be able to provide over 200W continuous, so using 1A fuses would not have been suitable. For the positive ends of the cells, I used a fuse to connect them to the bus bars, and on the negative end, I used resistor legs.
Connecting it all together and adding balancing wires
This pack can output a maximum of 20A continuous, so an XT60 can handle the current easily. Positive to positive and negative to negative connected with 16AWG wire and some 3mm heat shrink, which according to this chart, can handle 20amps, and with only about 1% voltage drop, which is perfectly acceptable. I did not have a 5 pin JST connector on hand for the balance connector, so I used a regular female pin header cut to 5 pins. It has the same pitch, so it is perfectly compatible, but it can be plugged in backwards, which can be dangerous - direct short circuit. I used 24AWG stranded wire for the balance cables and 1.5mm black and red heat shrink to label the positive and negative ends.
Cleaning it up and making it look good
I hot glued all the power and balance cables to the battery, leaving them as long as possible, but still securing every one. 2 pieces of plywood were cut slightly bigger than battery to protect the connections. Pieces of 5mm MDF were used as standoffs between the battery and the plywood so that there is no direct pressure on the connections to the fuses and bus bars. I sealed all the edges of the plywood (or chip board) with duct tape so that the edges do not fray or break in transport. I added my logo to the top of the plywood by printing it out mirrored on a sheet of sticky labels with the labels peeled off. The printer must be an inkjet printer, a laser printer will not work for this, as the ink (not toner) will not be absorbed into the label sticker backing, and will come off easily when pressed against the plywood. The writing did not come out as I had hoped, but that is due to the inconsistencies in the chip board. I finally sealed the ink in with a quick coat of clear acrylic spray paint.
Project by: Micah Black
Written By: Micah Black
For the past year or so, I have been testing 18650 Lithium-ion cells from recycled batteries in order to re-use them to power my projects. I started out testing the cells individually with an iMax B6, then got a few Liitokalaa Lii-500 testers and some TP4056 modules for charging, but the testing still took way too long for my liking. This project has been a long anticipated one for me, and I am now able to test 36 cells and charge 40 cells simultaneously.
A fair amount of people in the community of people re-using laptop batteries use the OPUS BTC3100 testers, but those were a little expensive for me. When I found the Liitokalaa Lii-500 testers for under $20 each on Aliexpress, I ordered 6 more to complement the 3 I already had, as well as 50 TP4056 chargers, and some 4 cells holders. The power supplies I used were from Aliexpress as well – 12V 30A and 5V 60A, but a better option would have been to used server power supplies.
I’m sure that almost everyone that has a basement lab is looking for every way possible to get more space, so using up a ton of desk space with a charging and testing station is not ideal. Such is the case for me, so I decided to make my testing station a sliding drawer underneath my desk.
Building this was fairly straightforward, but required a lot of time. I designed some 3D printed clips to hold the 10 4 cell holders and the 9 Liitokalaa Lii-500s to the plywood that I used as the base.
I connected the BAT+ pad on the TP4056 modules directly to the cell holders, and ran wire through the holes in the battery holder to connect the other end to BAT-. This was a very elegant solution, and only required 1 wire per slot, 40 in total.
Power lines for the TP4056s and Lii-500s were made out of 3 x 18AWG wire from old Christmas light string. I stripped the insulation, and twisted them all together using a clamp and a cordless drill.
I lined up the positive wire just in front of the TP4056s, and the negative wire was connected directly to the USB ports, which are grounded. To connect the 5V line to the IN+ pad of the TP4056s, I used leftover resistor legs, which were the perfect length. Connecting 12V power to the Liitokalaa chargers was done with the same Christmas light wire, as well as some DC barrel connectors, and plenty of 3mm heat shrink to protect against shorts.
Moving on to the AC wiring for the power supplies, I got a fused power socket with a switch, and connected it to each of the power supplies. All the AC wiring is done on the underside of the plywood, and is secured using some 3D printed cable clips, printed out on my i3 style printer. I attached the power supplies to the board using 3D Printed brackets. A small voltmeter was added to the 5V and 12V power supplies for a quick check of the voltage.
After plugging in the power cable and turning on the switch, everything worked great!
One thing that I noticed as I was charging 18650 with these TP4056 modules was that they got pretty hot (too hot to touch) at the CC part of the charging curve. I started by adding some small 8x8mm heat sinks to the TP4056 chips, and then adjusted the output of the 5V power supply as low as it could go. In this case, it was 4.9V. Now, they never get too hot to touch.
Project by: Micah Black
Written By: Micah Black