Most circuit boards any maker could need for their projects can be acquired online at modest cost, but what if you need something specific? [Giorgos Lazaridis] of pcbheaven.com has designed his own etching bath complete with a heater and agitator to sped up the process of creating your own custom circuit boards.
[Lazaridis] started by building a circuit to control — in a display of resourcefulness — a fish tank heater he would later modify. The circuit uses a PIC 16F526 microcontroller and two thermristors to keep the temperature of the etching bath between 38 and 41 degrees Celsius. The fish tank heater was gingerly pried from its glass housing, and its bimetallic strip thermostat removed and replaced with a wire to prevent it shutting off at its default 32 degrees. All of it is mounted on a small portable stand and once heated up, can etch a board in less than 10 minutes.
Once tried, even grown-ups just can’t let go of that hilariously funny Chewbacca mask. Also, the speaking toy literally cries out to be hacked. Weary of the whining Wookie, [John Park] set out to bring variety into Chewie’s mode of expression, expanding the mask’s memory and vocabulary to unprecedented levels.
A personal bartender is hard to come by these days. What has the world come to when a maker has to build their own? [Pierre Charlier] can lend you a helping hand vis-à-vis with HardWino, an open-source cocktail maker.
The auto-bar is housed on a six-slot, rotating beverage holder, controlled by an Arduino Mega and accepts drink orders via a TFT screen. Stepper motors and L298 driver boards are supported on 3D printed parts and powered by a standard 12V DC jack. Assembling HardWino is a little involved, so [Charlier] has provided a thorough step-by-step process in the video after the break.
In the surest sign that hardware hacking is the new hotness, Motorola and Farnell/Element 14 have developed an add-on board and SDK that will let you connect virtually anything to your mobile phone. Motorola is calling it the “Moto Mods” system, and it looks like its going to be a dedicated microcontroller that interfaces with the computer inside the phone and provides everything from GPIOs to DSI (video). Naturally, I2C, I2S, SPI, UART, even two flavors of USB are in the mix.
The official SDK, ahem Mods Development Kit (MDK), is based on the open Greybus protocol stack (part of Google’s Project Ara open phone project) and it’s running on an ARM Cortex-M4F chip. It’s likely to be itself fairly hackable, and even if the suggested US $125 price is probably worth it for the convenience, we suspect that it’ll be replicable with just a few dollars in parts and the right firmware. (Yes, that’s a challenge.)
The initial four adapter boards range from a simple breadboard to a Raspberry-Pi-hat adapter (hence the title). It’s no secret that cell phones now rival the supercomputers of a bygone era, but they’ve always lacked peripheral interfaces. We wish that all of the old smartphones in our junk box had similar capabilities. What do you say? What would you build with a cellphone if you could break out all sorts of useful comms?
Via HackerBoards, and thanks to [Tom] for the tip!
Magnetic gears are surprisingly unknown and used only in a few niche applications. Yet, their popularity is on the rise, and they are one of the slickest solutions for transmitting mechanical energy, converting rotational torque and RPM. Sooner or later, you’re bound to stumble upon them somewhere, so let’s check them out to see what they are and what they are good for.
We’ve all been there – hiking in the woods with a dead phone battery. No GPS, no way to Tweet that selfie from some hill with a great vista. It’s a disaster! But not if you have access to a little trailside junk and have the ingenuity to build this field-expedient water wheel generator to recharge your phone.
OK, it’s a stretch to imagine finding all the things needed for [Thomas Kim]’s hack. We’re only guessing at the BOM – the video below has little commentary, so what you see is what you get – but it looks like a garbage can at the trailhead might at least yield the materials needed to build the turbine. Water bottle bottoms and a couple of plastic picnic plates form the Pelton-like impeller, the frame looks like an old drying rack, and the axle appears to be a campfire skewer. But you might have a hard time finding the electrical side of the build, which consists of a stepper motor, a rectifier, and an electrolytic cap. Then again, you could get lucky and find a cast-off printer by the side of the road. No matter how he got the materials, it’s pretty cool to see an iPhone recharging next to a babbling brook in the woods.
Looking for a little more oomph from your trash-heap hydroelectric turbine? Maybe you need to look at this washing machine power plant build.
The history of the diode is a fun one as it’s rife with accidental discoveries, sometimes having to wait decades for a use for what was found. Two examples of that are our first two topics: thermionic emission and semiconductor diodes. So let’s dive in.
Vacuum Tubes/Thermionic Diodes
Our first accidental discovery was of thermionic emission, which many years later lead to the vacuum tube. Thermionic emission is basically heating a metal, or a coated metal, causing the emission of electrons from its surface.
Electroscope
In 1873 Frederick Guthrie had charged his electroscope positively and then brought a piece of white-hot metal near the electroscope’s terminal. The white-hot metal emitted electrons to the terminal, which of course neutralized the electroscope’s positive charge, causing the leafs to come together. A negatively charged electroscope can’t be discharged this way though, since the hot metal emits electrons only, i.e. negative charge. Thus the direction of electron flow was one-way and the earliest diode was born.
Thomas Edison independently discovered this effect in 1880 when trying to work out why the carbon-filaments in his light bulbs were often burning out at their positive-connected ends. In exploring the problem, he created a special evacuated bulb wherein he had a piece of metal connected to the positive end of the circuit and held near the filament. He found that an invisible current flowed from the filament to the metal. For this reason, thermionic emission is sometimes referred to as the Edison effect.
Thermionic diode. By Svjo [CC BY-SA 3.0], via Wikimedia CommonsBut it took until 1904 for the first practical use of the effect to appear. John Ambrose Fleming had actually consulted for the Edison Electric Light Company from 1881-1891 but was now working for the Marconi Wireless Telegraph Company. In 1901 the company demonstrated the first radio transmission across the Atlantic, the letter “S” in the form or three dots in Morse code. But there was so much difficulty in telling the received signal apart from the background noise, that the result was disputed (and still is). This made Fleming realize that a more sensitive detector than the coherer they’d been using was needed. And so in 1904 he tried an Edison effect bulb. It worked well, rectifying the high frequency oscillations and passing the signals on to a galvanometer. He filed for a patent and the Fleming valve, the two element vacuum tube or thermionic diode, came into being, heralding decades of technological developments in many subsequent types of vacuum tubes.
Vacuum tubes began to be replaced in power supplies in the 1940s by selenium diodes and in the 1960s by semiconductor diodes but are still used today in high power applications. There’s also been a resurgence in their use by audiophiles and recording studios. But that’s only the start of our history.
