DIY Power Supply and TS100 Outlet Combo Shows off Great Layout

Here’s a combination of two important electronics workbench tools into a single, cleanly-assembled unit. [uGen] created a DC power supply complete with a plug for the popular TS100 soldering iron, and it looks great! Most of the main components are familiar offerings, like a LM2596 DC to DC buck converter board and a DPS3003 adjustable DC power supply unit (we previously covered a DIY power supply based around the similar DPS5005.) The enclosure is an economical, featureless desktop instrument case whose panels were carefully cut to fit the necessary components. There’s one limitation to the combo: the unit uses a switch to either power an attached TS100 iron, or act as a general DC power supply. It cannot do both at once. So long as one doesn’t mind that limitation, it’s a nice bundle made from very affordable components.

It’s easy for something to look like a hack job, but to look clean and professional involves thoughtful measurement, planning, and assembly. Fortunately, [uGen] has supplied all the drawings and bill of materials for the project so there’s no need to start from scratch. Also, don’t forget that if the capabilities of the DPS power supply units leave you wanting a bit more, there is alternative firmware in the form of OpenDPS; it even offers a remote control feature by adding an ESP8266.

Building a Portable Solar-Powered Spot Welder: Nearly Practical!

Last time, we covered storing and charging a 3000 Farad supercapacitor to build a solar-powered, portable spot welder. Since then, I’ve made some improvements to the charging circuit and gotten it running. To recap, the charger uses a DC-DC buck converter to convert a range of DC voltages down to 2.6 V. It can supply a maximum of 5 A though, and the supercapacitor will draw more than that if allowed to.

Capacitor charge current decreases with time as the capacitor charges. Source: Hyperphysics

After some failed attempts, I had solved that by passing the buck converter output through a salvaged power MOSFET. A spare NodeMCU module provided pulse width modulated output that switched the MOSFET on for controlled periods of time to limit the charging current. That was fine, but a constant-voltage charger really isn’t the right way to load up a capacitor. Because the capacitor plates build up a voltage as it charges, the current output from a constant-voltage charger is high initially, but drops to a very low rate in the end.

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Glorious Body of Tracked ‘Mad Mech’ Started as Cardboard

[Dickel] always liked tracked vehicles. Taking inspiration from the ‘Peacemaker’ tracked vehicle in Mad Max: Fury Road, he replicated it as the Mad Mech. The vehicle is remote-controlled and the tank treads are partly from a VEX robotics tank tread kit. Control is via a DIY wireless controller using an Arduino and NRF24L01 modules. The vehicle itself uses an Arduino UNO with an L298N motor driver. Power is from three Li-Po cells.

The real artistic work is in the body. [Dickel] used a papercraft tool called Pepakura (non-free software, but this Blender plugin is an alternative free approach) for the design to make the body out of thin cardboard. The cardboard design was then modified to make it match the body of the Peacemaker as much as possible. It was coated in fiberglass for strength, then the rest of the work was done with body filler and sanding for a smooth finish. After a few more details and a good paint job, it was ready to roll.

There’s a lot of great effort that went into this build, and [Dickel] shows his work and process on his project page and in the videos embedded below. The first video shows the finished Mad Mech being taken for some test drives. The second is a montage showing key parts of the build process.

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Secret Book Light Switch

You enter a study and see a lightbulb hanging on the bookshelf. You try all the switches in the room — nothing is turning it on. Remembering you’re in [lonesoulsurfer]’s home, you realize that you’re going to have to start yanking on every book in sight.

While often associated with the likes of Bat-caves and other complicated hidden passageways, turning a shelved book into a secret switch isn’t complex in its own right. [lonesoulsurfer] is basing their build on one by B.Light Design revolving around a fan switch, some aluminium strips, a block terminal, fishing line, a hinge, and — of course — a book with a dust jacket and something to trigger.

Bend the aluminium into an angle bracket and drill a hole to attach the fan switch — ensuring the whole is small enough to fit behind and not distinguish the book you’re using. Cutting the hinge to the size of the book and screwing a strip of aluminium to it, both this lever and the fan switch’s bracket are then mounted on the shelf. Once a length of fishing twine is tethered to the lever and fitted through the book’s pages to the fan switch — ensuring the line is taut — sliding the dust jacket back onto the book completes the disguised switch!

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3D Printering: Print Smoothing Tests with UV Resin

Smoothing the layer lines out of filament-based 3D prints is a common desire, and there are various methods for doing it. Besides good old sanding, another method is to apply a liquid coating of some kind that fills in irregularities and creates a smooth surface. There’s even a product specifically for this purpose: XTC-3D by Smooth-on. However, I happened to have access to the syrup-thick UV resin from an SLA printer and it occurred to me to see whether I could smooth a 3D print by brushing the resin on, then curing it. I didn’t see any reason it shouldn’t work, and it might even bring its own advantages. Filament printers and resin-based printers don’t normally have anything to do with one another, but since I had access to both I decided to cross the streams a little.

The UV-curable resin I tested is Clear Standard resin from a Formlabs printer. Other UV resins should work similarly from what I understand, but I haven’t tested them.

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Look Out Nest — Here Comes the WIoT-2

[Dave] is an avid hacker and no stranger to Hackaday. When he decided to give his IoT weather display an upgrade, he pulled out all the stops.

The WIoT-2 is less of a weather station and more of an info center for their house — conveniently located by their front door — for just about anything [Dave] or his partner need to know when entering or exiting their home. It displays indoor temperature and humidity, date, time, garbage collection schedule, currency exchange rates, whether the garage door is open or closed, the hot tub’s temperature, a check in for his kids, current weather data from a custom station [Dave] built outside his house, and the local forecast.

WIoT-2’s display is a Nextion TFT and the brains behind the operation is a NodeMCU 8266. He made extensive use of Blynk to handle monitoring of the various feeds, and will soon be integrating master control for all the networked outlets in the house into the system. He found setting up the hardware to be fairly clear-cut but notes that he cannot have the screen powered on when uploading sketches to the NodeMCU.  He circumvented the problem by adding a latching switch to the screen’s power line.

[Dave] curated a robust explanation of his build that includes tips, tricks, code — and a how-to to boot! If you’re not already starting your own build of this info suite, you may be tantalized by some of his other projects.

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DIY Text-to-Speech with Raspberry Pi

We can almost count on our eyesight to fail with age, maybe even past the point of correction. It’s a pretty big flaw if you ask us. So, how can a person with aging eyes hope to continue reading the printed word?

There are plenty of commercial document readers available that convert text to speech, but they’re expensive. Most require a smart phone and/or an internet connection. That might not be as big of an issue for future generations of failing eyes, but we’re not there yet. In the meantime, we have small, cheap computers and plenty of open source software to turn them into document readers.

[rgrokett] built a RaspPi text reader to help an aging parent maintain their independence. In the process, he made a good soup-to-nuts guide to building one. It couldn’t be easier to use—just place the document under the camera and push the button. A Python script makes the Pi take a picture of the text. Then it uses Tesseract OCR to convert the image to plain text, and runs the text through a speech synthesis engine which reads it aloud. The reader is on as long as it’s plugged in, so it’s ready to work at the push of a button. We can probably all appreciate such a low-hassle design. Be sure to check out the demo after the break.

If you wanted to use this to read books, you’d still have to turn the pages yourself. Here’s a BrickPi reader that solves that one.

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