An Exhaustive Guide To Building 18650 Packs

June 12, 2019 by Jenny List 23 Comments

Most of us know the basics of building packs of lithium-ion batteries. We’re familiar with cell balancing and the need for protection circuitry, and we understand the intricacies of the various serial and parallel configurations. It’s still a process that can be daunting for the first-time pack-builder though, because the other thing that most of us know about lithium ion batteries is that getting things wrong can cause fires. Rule zero of hackerspaces is “Don’t be on fire”, so what’s to be done? Fortunately [Adam Bender] is on hand with an extremely comprehensive two-part guide to designing and building lithium-ion battery packs from cylindrical 18650 cells. (Edit 2025: re-linked through Internet Archive.)

In one sense we think the two-parter is in the wrong order. Part two takes us through all the technical details and theory, from lithium-ion chemistry to battery management systems and spot-welding nickel busbars, while part one shows us the construction of his battery pack. There are also a couple of videos, which we’ve placed below the break. It’s still not a job for the faint-hearted, but we’d say he’s produced about as professional and safe a pack as possible.

If spot welding worries you then it might be possible to build a pack without it. But it’s always worth considering: would you be better served buying one?

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Assembling A Lathe From Not A Lot

June 9, 2019 by Jenny List 36 Comments

Most people have a piece of equipment without which they consider their workshop or bench to be incomplete. For some, it is an oscilloscope, for others a bandsaw, but for many metalworkers, it is a lathe. Lathes are expensive if you are seeking a good one, quite cheap if you don’t mind a bad one, and sometimes even free if you can deal with a good one that’s very old and needs six burly friends and a forklift truck to move.

There is another way to acquire a lathe, and it’s one that [Sek Austria] demonstrates in the video below the break: build your own. It’s a fascinating demonstration of how machine tools evolved with each successive generation made by the last at every increasing precision. He achieves good-enough construction from a welded steel frame with little more than hand tools, and though his result is by no means a perfect lathe it does allow him to achieve the next level of machining precision. Off the shelf come a set of optical guide rails and linear bearings along with a chuck and tool holder, but the rest is all his. And the washing machine motor driving it is a touch of pure class, even though he is embarrassed enough to cover it with a glove for filming. Sometimes in our community, we adopt the sledgehammer to crack a nut methodology, using CNC or similar techniques to fabricate things that can be made more speedily with less accomplished methods. We couldn’t help wincing at his hammering in the vice to create the lead screw nut bracket, though.

As homemade lathes go, this one is surprisingly conventional. Others have been fashioned from engine parts, or concrete.

Thanks [Xavier] for the tip.

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Protect Your Coffee Machine With A Filter Monitor

June 9, 2019 by Jenny List 16 Comments

Coffee machines are delicate instruments, likely to be damaged by limescale. Thus they will often have a filter present, but filters have a limited capacity of water upon which they can be effective. At Make Bournemouth, they have approached the problem of when to change filters on their coffee machine by applying a bit of high-tech.

The water passing through the filter is monitored by a couple of DFRobot TDS modules, a flow meter, and a DS18B20 temperature sensor. The data from these is fed into an ESP32 dev board, which makes it available by a web interface for handy accessibility through a smartphone. It can then be used to work out how much of the filter’s capacity has been used, and indicate when a replacement is needed. All the code is available in a GitHub repository, and with luck now Bournemouth’s hackerspace will never see the coffee machine succumb to limescale.

Of course, this isn’t the first coffee maker water hack we’ve brought you. A year or two ago we told you about somebody making their pod coffee maker auto-fill too.

Panadaptors Didn’t Start With SDRs

June 8, 2019 by Jenny List 6 Comments

The must-have accessory on a modern all-singing, all-dancing amateur radio transceiver is a panadaptor. Inevitably driven by SDR technology, it’s a view of a band in the frequency domain, and it will usually be displayed as a “waterfall” giving a time dimension to see transmissions over a period.

[Bill Meara, N2CQR] reminds us that panadaptors are nothing new, indeed that they date back to the first half of the last century and don’t even need an SDR to work. And to prove it, he’s produced one for part of the 40-metre amateur band.

The principle behind an analogue panadaptor is simple enough, it’s a normal receiver whose local oscillator is given a linear periodic sweep over the desired frequency band and whose output drives the Y axis of an oscilloscope whose X axis is driven by the sweep. In [Bill]’s case the receiver is a BitX homebrew transceiver, and the swept local oscillator is provided by his Foeltech signal generator. A neat touch comes in the ‘scope being synchronised by triggering on a marker frequency at the bottom of the range being swept. He’s created a video showing it in action, which you can see below the break.

There are quite a few routes into making this type of simple spectrum analyser, indeed some of us have tried ti with TV tuners.

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Ask Hackaday: What Skills Would You Give A Twelve Year Old?

June 7, 2019 by Jenny List 84 Comments

In several decades of hanging around people who make things, one meets a lot of people fascinated by locks, lock picking, and locksport. It’s interesting to be sure, but it had never gripped me until an evening in MK Makerspace when a fellow member had brought in his lockpicking box with its selection of locks, padlocks, and tools. I was shown the basics of opening cheap — read easy from that— padlocks, and though I wasn’t hooked for life I found it to be a fascinating experience. Discussing it the next day a friend remarked that it was an essential skill they’d taught their 12-year-old, which left me wondering, just what skills would you give to a 12-year-old? Continue reading “Ask Hackaday: What Skills Would You Give A Twelve Year Old?” →

Spectrum Chiptunes On An STM

June 7, 2019 by Jenny List 5 Comments

Some of us here at Hackaday are suckers for a bit of chiptune music as the backdrop for many excellent times. The authentic way to create chiptunes is of course the original hardware, but in 2019 it’s far more common to do so with an emulator on a modern computer. That computer doesn’t have to sport a high-end processor and desktop operating system though, as [Deater] shows us with his ZX spectrum chiptune player on an STM32L46G Discovery board.

The impetus for the project came he tells us while teaching students to code simple sine wave music players, having code already in the bag for emulating the classic AY-3-8910 sound chip on the Raspberry Pi and the Apple II he decided to port that to the STM32L476 dev board. An earlier version used the internal DAC, but this was refined to send I2S data to an external DAC. The code can be had from GitHub (confusingly buried among code for an LED driver), and we’ve attached a video below of it playing some chiptune goodness.

Of course, Sinclair chiptunes don’t grab all the limelight. There have been plenty of Nintendo and Sega players too. You might also recognize [Deater] from his non-chiptune work, porting Portal to the Apple ][.

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The UK Drone Community Fights Back, Gains FOI Admission Of No Tangible Drone Evidence

June 4, 2019 by Jenny List 33 Comments

Regular Hackaday readers will have noted a succession of stories following the reports of drones in the air over British airports and in proximity to aircraft. We’ve consistently asked for a better quality of investigation and reporting into these cases, because so far the absence of reported tangible evidence of a drone being present casts doubt on the validity of the official reaction. For too long the official records of air proximity incidents have relied upon a shockingly low standard of proof when apportioning blame to drone operators, and this situation has contributed to something of a panic over the issue.

It seems that some members of the British drone flying community are on the case though. Airprox Reality Check are a group analysing air proximity reports and linking them to contemporary ADS-B and weather records to identify possible explanations. They have devised a rating system based upon a number of different metrics in an attempt to quantify the reliability of a particular report, and they are tabulating their analysis of air proximity reports on a month by month basis. This includes among many analyses such gems as Airprox Report #2019046, in which an Embraer 170 flying at 9000 feet and 20 km offshore reported a drone in close proximity. The Airprox Reality Check analysis points out that no known drone could manage that feat, and refers to a passing Boeing 737 revealed through ADS-B data as a more likely culprit.

Their latest news is that they have made a Freedom of Information request to the Air Proximity Board, asking for what evidence the Board has of a drone having been involved in any of the over 350 incidents in UK airspace having been reported as involving drones. The official response contains the following quote:

in all cases UKAB has no confirmation that a drone has flown close to an aircraft other than the report made by the pilot(s). Similarly, other than from the report of the pilot(s), UKAB has no confirmation that a drone was involved.

This confirms the view of the multirotor and drone community that has been reported by Hackaday in the past, that the whole British drone panic has been based upon unreliable and uncorroborated reports from eyewitnesses with little direct experience of multirotors. If any irresponsible drone operator is flying into close proximity with aircraft or otherwise into protected airspace then it goes without saying that they should be prosecuted, yet it seems that the community is being punished as though this had happened when the reality is that no such acts are proven to have occurred.