PID Control with Arduino

Experience — or at least education — often makes a big difference to having a successful project. For example, if you didn’t think about it much, you might think it is simple to control the temperature of something that is heating. Just turn on the heater if it is cold and turn it off when you hit the right temperature, right? That is one approach — sometimes known as bang-bang — but you’ll find there a lot of issues with that approach. Best practice is to use a PID or Proportional/Integral/Derivative control. [Electronoob] has a good tutorial about how to pull this off with an Arduino. You can also see a video, below.

The demo uses a 3D printer hot end, a thermocouple, a MAX6675 that reads the thermocouple, and an Arduino. There’s also an LCD display and a FET to control the heater.

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A Hacker’s Epic Quest to Keep His Son Entertained

Little humans have a knack for throwing a wrench in the priorities of their parents. As anyone who’s ever had children will tell you, there’s nothing you wouldn’t do for them. If you ever needed evidence to this effect, just take a gander at the nearly year-long saga that chronicles the construction of an activity board [Michael Teeuw] built for his son, Enzo.

Whether you start at the beginning or skip to the end to see the final product, the documentation [Michael] has done for this project is really something to behold. From the early days of the project where he was still deciding on the overall look and feel, to the final programming of the Raspberry Pi powered user interface, every step of the process has been meticulously detailed and photographed.

The construction methods utilized in this project run the gamut from basic woodworking tools for the outside wooden frame, to a laser cutter to create the graphical overlay on the device’s clear acrylic face. [Michael] even went as far as having a custom PCB made to connect up all the LEDs, switches, and buttons to the Arduino Nano by way of an MCP23017 I2C I/O expander.

Even if you aren’t looking to build an elaborate child’s toy that would make some adults jealous, there’s a wealth of first-hand information about turning an idea into a final physical device. It isn’t always easy, and things don’t necessarily go as planned, but as [Michael] clearly demonstrates: the final product is absolutely worth putting the effort in.

Seeing how many hackers are building mock spacecraft control panels for their children, we can’t help but wonder if any of them will adopt us.

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Need a Thousand Extra PWM Pins?

If your Arduino runs out of I/O lines, you can always add one of the several I/O expander chips that takes a serial interface to set its several pins. Or perhaps you could buy something like an Arduino Mega, with its extra sockets to fulfil your needs. But what would you do if you really needed more pins, say a thousand of them? Perhaps [Brian Lough] has the answer. OK, full disclosure: If you really need a thousand, the video isn’t exactly for you, as he shows you how to add up to 992 PWM outputs. The chip he uses works with any microcontroller (the video shows an ESP8266), and we suppose you could use two daisy chains of them and break the 1,000 barrier handily.

We like how short the video is (just two minutes; see below) as it gets right to the point. The PCA9685 chip gives you 16 12-bit PWM channels via an I2C interface. You can daisy chain up to 62 of the boards to get the 992 outputs promised.

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Art Deco Radio Gets FM Reception

Taking a vintage radio and cramming it full of modern, Internet-connected, guts has long been a staple of the hacking and making scene. While some might see it as a crime to take what’s arguably a legitimate piece of history and turn it into nothing more than a slipshod case for the Raspberry Pi, we have to admit there’s a certain appeal to the idea. Taking the beauty of classic design and pairing it with more modern capabilities is getting the best of both worlds.

But this project by [Nick Koumaris] is a somewhat unique take on the concept. Rather than sacrificing a real vintage piece of hardware to house the electronics, he’s designed a 3D printable case that looks like a classic 1936 AWA Radiolette. But what’s really interesting to us is that he then puts a basic FM radio inside of it.

That’s right, no Internet radio streaming or smartphone Bluetooth compatibility here. It’s just a regular FM radio, not entirely unlike the kind of hardware you’d expect to be inside of a classic radio. Of course, it’s much more modern, and [Nick] actually built it himself from a TEA5767 FM radio module and an Arduino Pro Mini.

While functionally it might not be terribly exciting, we do appreciate that he went through the trouble to make a vintage-looking user interface for the radio. While physical buttons would arguably have been more appropriate given the era, the art deco inspired font and graphics that show on the device’s Nokia 5110 LCD do look really slick.

Purists will surely be happy to see another project where a piece of vintage piece of audio equipment wasn’t sacrificed at the Altar of Hack, but we’ve also played host to many projects which weren’t nearly as concerned with historical preservation.

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Reviving an Electron Microscope with Arduino

We don’t know about you, but when our friends ask us if we want to help them fix something, they’re usually talking about their computer, phone, or car. So far it’s never been about helping them rebuild an old electron microscope. But that’s exactly the request [Benjamin Blundell] got when a friend from a local hackerspace asked if he could take a look at a vintage Cambridge Stereoscan 200 they had found abandoned in a shed. Clearly we’re hanging out with the wrong group of people.

As you might imagine, the microscope was in desperate need of some love after spending time in considerably less than ideal conditions. While some of the hackerspace members started tackling the hardware side of the machine, [Benjamin] was tasked with finding a way to recover the contents of the scope’s ROM. While he’s still working on verification, the dumps he’s made so far of the various ROMs living inside the Stereoscan 200 have been promising and he believes he’s on the right track.

The microscope uses a mix of Texas Instruments 25L32 and 2516 chips, which [Benjamin] had to carefully pry out after making sure to document everything so he knew what went where. A few of the chips weren’t keen on being pulled from their home of 30-odd years, so there were a few broken pins, but on the whole the operation was a success.

Each chip was placed in a breadboard and wired up to an Arduino Mega, as it has enough digital pins to connect without needing a shift register. With the wiring fairly straightforward, [Benjamin] just needed to write up some code to read the contents of the chip, which he has graciously provided anyone else who might be working on a similar project. At this point he hasn’t found anything identifiable in his ROM dumps to prove that they’ve been made successfully, all he really knows right now is that he has something. At least it’s a start.

More and more of these older electron microscopes are getting a second lease on life thanks to dedicated hackers in their home labs. Makes you wonder if there’s ever going to be a piece of hardware the hacker community won’t bend to their will.

A Well-Chronicled Adventure in Tiny Robotics

Some of us get into robotics dreaming of big heavy metal, some of us go in the opposite direction to build tiny robots scurrying around our tabletops. Our Hackaday.io community has no shortage of robots both big and small, each an expression of its maker’s ideals. For 2018 Hackaday Prize, [Bill Weiler] entered his vision in the form of Project Johnson Tiny Robot.

[Bill] is well aware of the challenges presented by working at a scale this small. (If he wasn’t before, he certainly is now…) Forging ahead with his ideas on how to build a tiny robot, and it’ll be interesting to see how they pan out. Though no matter the results, he has already earned our praise for setting aside the time to document his progress in detail and share his experience with the community. We can all follow along with his discoveries, disappointments, and triumphs. Learning about durometer scale in the context of rubber-band tires. Exploring features and limitations of Bluetooth hardware and writing code for said hardware. Debugging problems in the circuit board. And of course the best part – seeing prototypes assembled and running around!

As of this writing, [Bill] had just completed assembly of his V2 prototype which highlighted some issues for further development. Given his trend of documenting and sharing, soon we’ll be able to read about diagnosing the problems and how they’ll be addressed. It’s great to have a thoroughly documented project and we warmly welcome his robot to the ranks of cool tiny robots of Hackaday.io.

Pavement Projection Provides Better Bicycle Visibility at Night

Few would question the health benefits of ditching the car in favor of a bicycle ride to work — it’s good for the body, and it can be a refreshing relief from rat race commuting. But it’s not without its perils, especially when one works late and returns after dark. Most car versus bicycle accidents occur in the early evening, and most are attributed to drivers just not seeing cyclists in the waning light of day.

To decrease his odds of becoming a statistics and increase his time on two wheels, [Dave Schneider] decided to build a better bike light. Concerned mainly with getting clipped from the rear, and having discounted the commercially available rear-mounted blinkenlights and wheel-mounted persistence of vision displays as insufficiently visible, [Dave] looked for ways to give drivers as many cues as possible. Noticing that his POV light cast a nice ground effect, he came up with a pavement projecting display using four flashlights. The red LED lights are arranged to flash onto the roadway in sequence, using the bike’s motion to sweep out a sort of POV “bumper” to guide motorists around the bike. The flashlight batteries were replaced with wooden plugs wired to the Li-ion battery pack and DC-DC converter in the saddle bag, with an Arduino tasked with the flashing duty.

The picture above shows a long exposure of the lights in action, and it looks very effective. We can’t help but think of ways to improve this: perhaps one flashlight with a servo-controlled mirror? Or variable flashing frequency based on speed? Maybe moving the pavement projection up front for a head-down display would be a nice addition too.