18650 Brings ESP8266 WiFi Repeater Along For The Ride

We’re truly fortunate to have so many incredible open source projects floating around on the Internet, since there’s almost always some prior art you can lean on. By combining bits and pieces from different projects, you can often save yourself a huge amount of time and effort. It’s just a matter of figuring out how all the pieces fit together, like in this clever mash-up by [bethiboothi] that takes advantage of the fact that the popular TP4056 lithium-ion battery charger module happens to be almost the exact same size of the ESP-01.

By taking a 3D printed design intended to attach a TP4056 module to the end of an 18650 cell and combining it with an ESP8266 firmware that turns the powerful microcontroller into a WiFi repeater, [bethiboothi] ended up with a portable network node that reportedly lasts up to three days on a charge. The observed range was good even with the built-in PCB antenna, but hacking on an external can get you out a little farther if you need it.

While it doesn’t appear that [bethiboothi] is using it currently, the esp_wifi_repeater firmware does have an automatic mesh mode which seems like it would be a fantastic fit for this design. Putting together an impromptu mesh WiFi network with a bunch of cheap battery powered nodes would be an excellent way to get network connectivity at an outdoor hacker camp, assuming the ESP’s CPU can keep up with the demand.

GBA Gets Homebrew USB Charging Upgrade

Sure there are pre-made kits to add a rechargeable battery and USB-C compatibility to Nintendo’s venerable Game Boy Advance, but [HorstBaerbel] thought he could throw together something similar for a fraction of the price. Plus, he wouldn’t have to wait on shipping. The end result might not be quite as polished, but it’s certainly impressive for what’s essentially a junk bin build.

The star of the show is the popular TP4056 lithium-ion charger module. [HorstBaerbel] went with the more common micro USB version, but these boards are also available with USB-C should you want to embrace the future. The module fits nicely inside the original battery compartment while while still leaving room for a 1,000 mAh pouch cell. The 4.2 V output of the fully charged battery is a bit too high for the Game Boy’s liking, so he used the forward voltage drop of a diode to bring it down to a more acceptable 3.5 V.

Naturally this does waste a good deal of energy, especially compared to the DC-DC converters used in commercial offerings like the CleanJuice, but it still delivers a respectable seven hours of runtime. The only issue with this modification seems to be that you’ve got just five minutes to save your progress and shut down when the GBA’s low-battery light goes on; but what’s life without a little excitement?

While not nearly extreme as some of the other GBA modifications we’ve seen over the years, this project is yet another example of the seemingly unlimited hacking potential of Nintendo’s iconic Game Boy line.

Handy Tool Drains 18650 Cells So You Don’t Have To

Draining a battery is easy. Just put a load across the terminals, maybe an incandescent bulb or a beefy power resistor, and wait. What’s quite a bit trickier is doing so safely. Put too large a load on, or leave it connected for longer than necessary, and you can end up doing damage to the cell. Not convinced he’d always remember to pull the battery out of his jury-rigged discharger at the opportune moment, [Jasper Sikken] decided to come up with a simple tool that could automatically handle the process with the cold and calculating precision of silicon.

V4 used the protection module from a pouch battery.

At a glance we can see the major components you’d expect in a discharger: a fairly simple PCB, four ceramic power resistors, a holder for a single 18650 cell, and a rocker switch to connect it all together. But wait, what’s that a TP4056 charging module doing in there?

While its presence technically makes this device a battery charger, [Jasper] is actually using it for the onboard protection IC. With the charging module between the cell and the power resistors, it will cut the connection when the voltage drops to 2.4 V. Oh yeah, and it can charge the battery back up if you connect up a USB cable.

[Jasper] says his little tool works great, with the resistor array putting just enough load on the battery to pull it down quickly without getting so hot that they’re dangerous to have exposed. He estimates the BOM for this gadget runs around $2 USD, and is considering offering it as a kit on Tindie in the near future.

If you’re looking for something a bit more advanced, [Jasper] built a programmable load a few years back that can discharge batteries and test power supplies all while logging the data to your computer for later analysis.

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Trashed Tablet Lives Again Thanks To New Charger IC

Have you ever pulled a piece of electronics from the trash that looked like nothing was wrong with it, only to take it home and find out it really is dead? Since you’re reading Hackaday, we already know the answer. Trash picking is an honored hacker tradition, and we all know it’s a gamble every time you pull something from the curb. But when the Samsung Galaxy Tab S that [Everett] pulled from the e-waste bin wouldn’t take a charge, he decided to crack it open and see if it was really beyond repair.

The first step was using a USB power meter to see if the tablet was actually pulling any current when plugged in. With just 10 mA on the line, [Everett] knew the device wasn’t even attempting to charge itself. So his next step was to pull the battery and charge it from a bench supply. This got the tablet to wake up, and as far as he could tell, everything else worked as expected. It seemed like the only issue was a blown charging circuit.

Where we’re going, we don’t need ribbon cables.

Now at this point, [Everett] could have just gone online and bought a new motherboard for the tablet and called it a day. But where’s the fun in that? Instead, he wired up a simple charging circuit using a TP4056 IC on a scrap of flexible PCB and mounted it to a square of Kapton tape. He then used 34 AWG magnet wire to connect it between the tablet’s USB port and the battery, bypassing the tablet’s electronics entirely.

The fix worked, but there was a slight problem. Since the TP4056 only goes up to 4.2 V and the battery maxes out at 4.35 V, [Everett] says his hacked charger can only bring the tablet up to 92% capacity according to Android. But considering the alternative, we think its more than a worthy trade-off.

It’s easy to dismiss tablets as largely disposable devices, but this isn’t the first time we’ve seen somebody save one with little more than solder and patience. Of course, what you do with that old tablet once you get it fired back up is another story entirely.

Building A USB-C Charger For Canon NB-4L Batteries

One of the most appealing aspects of USB-C is that it promises to be a unified power delivery system. You’ll no longer need to have a separate power cords for for your phone, camera, and laptop; physically they’ll all use USB-C connectors, and the circuitry in the charger will know how much juice to send down the line for each gadget. But in reality, we’ve all got at least a few pieces of older equipment that we’re not about to toss in the trash just because it doesn’t support the latest USB spec.

Note the relocated status LEDs.

Case in point, the old Canon camera that [Purkkaviritys] modified to take infrared pictures. Instead of abandoning it, he decided to make a custom USB-C charger for its NB-4L batteries. Since they’re just single cell 3.7 V lithium-ions, all he had to do was wire them up to the ubiquitous TP4056 charger module and design a 3D printed case to hold everything together.

He did go the extra mile and replace the SMD charging indicator LEDs on the PCB with 5 mm LEDs embedded into the 3D printed enclosure, though you could certainly skip this step if you were in a hurry. We imagine if you print the enclosure in a light enough color, you should be able to see the original LEDs glowing through the plastic.

This project is yet another example of how incredibly useful the TP4056 module really is. If there’s even a chance you might want to build a rechargeable gadget in the near future, you should have a few of these cheap boards ready to go in the parts bin.

The Swiss Army Knife Of Bench Tools

[splat238] had a ton of spare sensors laying around that he had either bought for a separate project or on an impulse buy, so he knew he had to do something with them. He decided to build his own digital multi-tool focusing on sensors that would be particularly useful in a workshop setting. Coincidentally, he was inspired by a previous hack that we covered a while back.

He’s equipped his device with a bubble level, tachometer, IR thermometer, protractor, laser pointer, and many, many more features that would make great additions to any hacker’s workspace. There’s a good summary of each sensor, making his Instructable somewhat of a quick guide to common sensing modalities for hardware designers. The tachometer, thermometer, laser pointer, and a few other capabilities are notable upgrades from the project we highlighted previously. We also appreciate the bigger display, allowing for more detailed user feedback particularly in using the compass and bullseye digital level among other features.

The number of components in [splat238’s] build is too extensive to detail one-by-one in this article, so please see his Instructable linked above for all the details. [splat238] made his own PCB for mounting each sensor and did a good job making the design modular so you wouldn’t need to add certain components if you don’t need them. Most of the components take some through-hole soldering with only a handful of 0805 resistors required otherwise. The housing was designed such that the user can handle the tool with one hand and can switch between each function with a push of a button.

Finally, the device is powered using a rechargeable lithium-polymer battery making it very reusable. And, if there weren’t enough features already, the battery can be charged via USB or through two solar panels mounted into the housing unit. Okay, solar charging might be a case of featuritis, but still a cool build either way.

Check out some other handy DIY tools on Hackaday.

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DIY Pocket MP3 Player

When [Neutrino-1] saw DFRobot’s DFPlayer module, he decided he wanted to make his own retro MP3 player. This tiny module comes packed with a ton of interesting capabilities such as EQ adjustment, volume control, and a 3 watt amplifier amongst other things. It can even play ads in between songs, should you want such a thing.

Controlling the DFPlayer module is easy using serial commands from a microcontroller, making it a convenient subsystem in bigger projects, and a potential alternative to the popular VLSI chips or the hard to come by WT2003S IC. [Neutrino-1] does a good job walking readers through the build making it fairly easy to remix, reuse, and reshare.

With the hardware sorted, all you’ve got to do is flash the firmware and load up an SD card with some MP3s. There’s even a small Python GUI to help you get your new player up and running. [Neutrino-1] also introduces users to the U8g2 display library which he says is a bit more feature-rich than the common Adafruit SSD1306 library. Great job [Neutrino-1]!

While you’re here, take a look at some of our other MP3 projects.

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