Dispensing Solder Paste Automatically

Through-hole chips are slowly falling by the wayside, and if you want to build something with new parts you will be using surface mount components. This means spreading paste and throwing it in the toaster oven. Of course, if you don’t want to take the time to get a stencil for your solder paste, you can always lay it down by hand. For that, [owhite] has created a tiny, handheld, robotic solder paste dispenser. It’s a robotic pen that dispenses just the right amount of solder paste on your pads.

The design of this solder paste dispenser is basically a syringe filled with paste and a stepper motor to push the plunger down. Devices like this already exist, and the i-extruder can be had for somewhere around two hundred bucks. Why buy when you can build, so [owhite] set out to create his own.

The key to a successful solder paste pen, it seems, is driving the plunger with a small NEMA 8 stepper motor, using a very fine pitch on the threads of the gears pushing the plunger down, and surprisingly finding a small-diameter syringe. [owhite] found the last bit in the form of a gas-tight syringe with a nylon gasket. The electronics consist of just a Teensy 3.2, DRV8825 stepper driver, footswitch, and an OLED for a UI.

With just a few parts, [owhite] managed to create a solder paste pen that’s better than the commercial i-extruder, and with a bit of practice can be used to place paste on some SMD pads.

Automating The Design Of Word Clocks

Word clocks, or a matrix of light-up letters that spell out the time, are a standard build for all enterprising electronics enthusiasts. The trouble is finding the right way to drive a matrix of LEDs and the significant amount of brainpower that goes into creating a matrix of letters that will spell out the time without making it look like it’s supposed to spell out the time.

For his Hackaday Prize entry this year, [Stephen Legge] is creating a standard toolkit that makes word clocks easier to build. It’s a hardware and software project, allowing for LED matrices of any reasonable size, and the software to make a grid of letters that only spells out the words you want and not the four-letter ones you don’t.

The hardware for this project is built around the IS31FL3733 LED driver from ISSI. This is an interesting chip that takes I2C in and spits out a LED matrix with very few additional support components. This chip provides [Stephen] with a 12×16 single-color LED matrix, which is more than enough for a word clock.

Where this build gets slightly more interesting is the creation of a custom matrix of letters that will still spell out ‘quarter to noon’ when lit in the appropriate way. This is a big challenge in creating a customized word clock; you could always borrow the layout of the letters from another word clock, but if you want customized phrases, you’ll either have to sit down with a pencil and graph paper, or write some software to do it automatically.

It’s a great project, and since all of [Stephen]’s work is being released under Open Source licenses, it’s a great entry to the first portion of the Hackaday Prize where we’re challenging hardware creators to build Open Hardware.

Fail Of The Week: An Electric Bicycle, Powered By AA Batteries

Very slowly, some very cool parts are coming out on the market that will make for some awesome builds. Supercapacitors are becoming a thing, and every year, the price of these high power supercaps go a little lower, and the capacity gets a little higher. It’s really only a matter of time before someone hacks some supercaps into an application that’s never been seen before. The Navy is doing it with railguns, and [David] is building an electric bike, powered by AA batteries. While [David]’s bike technically works with the most liberal interpretation of ‘technically’, it’s the journey that counts here.

This project began as an investigation into using supercapacitors in an electric bicycle. Supercaps have an energy density very much above regular capacitors, but far behind lithium cells. Like lithium cells, they need a charge balancer, but if you manage to get everything right you can trickle charge them while still being able to dump all that power in seconds. It’s the perfect application for a rail gun, or for slightly more pedestrian applications, an electric bike with a hill assist button. The idea for this build would be to charge supercaps from a bank of regular ‘ol batteries, and zoom up a hill with about fifteen seconds of assistance.

The design of the pulsed power DC supply is fairly straightforward, with a mouthful of batteries feeding the supercap array through boost regulators, and finally going out to the motor through another set of regulators. Unfortunately, this project never quite worked out. Everything worked; it’s just this isn’t the application for the current generation of supercapacitors. There’s not enough energy density in [David]’s 100F supercaps, and the charging speed from a bunch of AA batteries is slow. For fifteen minutes of charging, [David] gets about fifteen seconds of boost on his bike. That’s great if you only ever have one hill to climb, but really useless in the real world.

That doesn’t mean this project was a complete failure. [David] now has a handy, extremely resilient array of supercaps that will charge off of anything and provide a steady 24V for a surprising amount of time. Right now, he’s using this scrapped project as a backup power supply for his 3D printer. That 100 Watt heated bed slurps down the electrons, but with this repurposed supercap bank, it can survive a 20 second power outage.

It’s a great project, and even if the technology behind supercaps isn’t quite ready to be used as a boost button on an electric bike, it’s still a great example of DIY ingenuity. You can check out [David]’s demo of the supercap bank in action below.

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Reprogramming Cheap WiFi Outlets

If you want to retrofit your home with smart outlets and lightbulbs, bust out your wallet. You can easily spend forty dollars for a smart light bulb at your local home supply store, and strips of smart sockets could cost sixty. When [coogle] found a WiFi-enabled four-outlet power strip on Amazon, he couldn’t resist. Sure, the no-name strip would be locked down behind a stupid iPhone interface and will probably turn your house into a botnet, but never mind that: you can easily reprogram these power strips to be whatever you want.

After receiving these power strips and tearing them open, [coogle] found exactly what you would expect from a no-name white goods manufacturer. There’s a board with an Espressif chip and a WiFi antenna, and a second board with a few relays, with a few wires connecting the two. You only need to browse AliExpress for a few minutes to figure out what’s going on here. The brains of the outfit are in the ESP8266, and if you can control that, you have your own Internet of Power Strips.

The problem, then, was reprogramming the ESP8266. This was a version of the chip [coogle] hadn’t seen before, but a quick query with the Google Mother Brain revealed it was a WT8266-S1 module, with all the pins required for programming easily accessible on a convenient header. After connecting this header up to an ESP programming board, [coogle] had all the relevant information including the capacity of the Flash. There’s still a bit more work to make this a functional WiFi power outlet, namely figuring out which GPIOs and wires connect to which relays, but this is effectively a completely Open IoT device right now. All you have to do is bring your own firmware.

Hackaday Links: April 15th, 2018

San Fransisco is awash in electric scooters. Three companies — Lime, Bird, and Spin — have been dumping ‘smart’ electric scooters on the sidewalks of San Fransisco over the last few weeks. The business plan for all these companies is to allow anyone to ride them via an app. $1 unlocks the scooter, and rides are fifteen cents a minute. No one, it appears, is looking at the upside of abandoned, dead electric scooters: they’re a remarkable source of lithium batteries and brushless motors. Hello, my name is Mr. Cyberpunk. My friends and I drive around the city collecting abandoned electric scooters to harvest their batteries and motors. A quick hit from a drill in the middle of the top panel of a Bird scooter disables the cellular modem, but then you don’t get to harvest the Particle dev board. You’re welcome, Mr. Doctorow, for the scene in your next novel.

There are a huge number of tips and tricks that are obvious if you already know them, and genius if you don’t. Working with wood? Need to hide a gap? Use sawdust and wood glue to make DIY wood filler. The trick here is using sawdust from whatever you’re trying to hide a gap in, but it’s not a bad idea to keep a few small containers of different sawdusts if you’re working with exotic tropical hardwoods. Titebond III, mango.

Ever since the Bayeux tapestry meme generator of 2003, embroidery has been recognized as a legitimate art form. [Irene Posch] is using traditional embroidery skills to create a computer. Conductive thread exists, but you can’t make a computer out of just wire; you need some sort of switching element. This is a relay computer, with the relays built out of beads, coils of conductive thread, and a tiny flippy bit. This is the best picture you’re going to get of the relay. This is still a work in progress and the density of components means this will probably never meet any reasonable definition of ‘computer’, but it is digital logic, done completely with tools in the embroidery toolset.

You know what’s awesome? Hashtag Badgelife. What is Badgelife? It’s the hardware demoscene of independent electronic conference badges, mostly going down at DEF CON every year. This year, Badgelife is bigger than ever. Want proof? AND!XOR, the folks behind the infamous Bender badge and last year’s Hunter S. Rodriguez badge have unleashed this year’s design. It was a Kickstarter, until it sold out. The DC Furs have launched their pre-order whatever for a badge filled with LEDs and fleas. Most surprisingly, there will now be an official mini-village of Badgelife at this year’s Defcon! This is a hardware demoscene, people, and if you want to be as cool as the guys rocking Amiga homebrew in 1993, you gotta get on board with the badgelife.

Rotary Encoders Become I2C Devices

Rotary encoders are the bee’s knees. Not only do you get absolute positioning, you can also use a rotary encoder (with a fancy tact button underneath) for an easy UI for any electronics project. There’s a problem with rotary encoders, though: it’s going to use Gray code or something weird, and getting a rotary encoder to work with your code isn’t as easy as a simple button.

For his Hackaday Prize project, [fattore.saimon] has come up with the solution for using multiple rotary encoders in any project. It’s a board that turns a rotary encoder into an I2C device. Now, instead of counting rising and falling edges, adding a rotary encoder to a project is as easy as connecting four wires.

The project is built around the PIC16F18344, a small but surprisingly capable microcontroller that reads a rotary encoder and spits data out as an I2C slave device. Also on board are a few pins for an RGB LED, general purpose pins, the ability to set all seven bits of the I2C address (who wants 127 rotary encoders?), and castellated holes for connecting several boards together.

This project is an update of [fattore]’s earlier I2C Encoder, and there are a lot of improvements in the current version. It’s slightly smaller, has better connectors, and uses a more powerful microcontroller. That’s just what you need if you want a ton of rotary encoders for all those cool interactive projects.

Resuming Failed 3D Prints Automatically

What happens to your 3D printer if the power goes out? What happens if there’s a jam in the nozzle? What happens if your filament breaks, runs out, or turns into a plate of spaghetti? For all these situations, the print fails, wasting plastic and time. For his Hackaday Prize entry, [robert] has come up with a tiny device that saves all those failed prints, and it does it without batteries or a UPS.

The idea behind [robert]’s box is to monitor all the G-code being sent to the printer, and allow a print to be resumed after a failure. The design is simple enough — just a USB mini port on one end, a USB A port on the other, and three buttons in between. This box logs the G-code, and if the printer happens to fail, the box will spring into life allowing you to resume a print from any Z position.

Already [robert] has tested this box on a number of printers including the Prusa i3, the Creality CR-10, and the ever-popular, explodey Anet A8. The project has already gone through a few hardware revisions and there is, of course, a fancy 3D printed enclosure for the board. It’s a great project, and one of the more interesting 3D printing tools we’ve seen in this year’s Hackaday Prize.