Sometime in the very distant future, the Universe will become the domain of black holes. Energy and entropy will be compressed into minuscule quantum fluctuations. Even in this domain of nothingness, there will still be one unassailable truth: you should not buy a 3D printer on Kickstarter.
We’re no strangers to failed 3D printer crowdfunding campaigns. Around this time last year, backers for the Peachy Printer, an inordinately innovative resin printer, found out they were getting a timeshare in Canada instead of a printer. This was unusual not because a crowdfunding campaign failed, but because we know what actually happened. It’s rare to get the inside story, and the Peachy Printer did not disappoint.
For the last few months, we’ve been watching another crowdfunding campaign on its long walk to the gallows. The Tiko 3D printer is another 3D printer that looks innovative, and at the time of the crowdfunding campaign, the price couldn’t be beat. For just $179 USD, the backers of the Tiko printer would receive a 3D printer. Keep in mind the Tiko launched nearly two years ago, when a bargain-basement printer still cost about $400. Fools and money, or something like that, and the Tiko 3D printer campaign garnered almost three million dollars in pledges.
Now, after almost two years of development, Tiko is closing up shop. In an update posted to the Tiko Kickstarter this week, Tiko announced they are laying off their team and winding down operations. It’s a sad but almost predictable end to a project that could have been cool. Unlike so many other failed crowdfunding campaigns, Tiko has given us a post-mortum on their campaign. This is how the Tiko became a standout success on Kickstarter, how it failed, and is an excellent example of the difference between building one of something and building ten thousand.
We want you to make the next Hackaday live event great. This is an Unconference in San Francisco on Saturday, March 18th and it depends completely on you. Get signed up now!
You’re in Control of the Hackaday Unconference
An unconference is a live event where you decide the topic, guide the discussion, and generally make it an epic Saturday. We have a handful of speakers lined up to help get things started. But we also want you to be ready to give a talk. Everyone that shows up should be prepared to stand up and deliver eight minutes on something they find exciting right now.
Kicking off the night we’ll ask each person to tell us the title or topic of their talk and approximate length of the presentation. Once all the titles are written down we’ll hammer out the schedule right then and there. If you haven’t been to an unconference this is the time to sign up, collect your thoughts, and jump into an afternoon of extemporaneous idea-sharing. If you have been to an unconference we’re guessing you signed up as soon as you saw this announcement.
The MeArm Pi is a fantastic little robot kit that was the first place winner of the Enlightened Pi contest here on Hackaday. It’s crushing the Shitty Robots subreddit, and compared to the old MeArm kit, it’s much, much simpler to assemble. Ask me how I know. Now the MeArm Pi is a Kickstarter. This tiny robot arm is programmable in everything from Scratch to Perl. It’s highly recommended for children ages 8 to those wanting to recreate the opening scene of Pee Wee’s Big Adventure.
Almost a year ago, Lulzbot unveiled their latest 3D printer at the Midwest RepRap Festival. The Taz 6 is a great printer, but it’s a bit of a departure from their previous designs. The biggest change was the ‘brain box’, the controller box that encases the power supply, stepper drivers, and other associated electronics. Last year, Lulzbot said they would be selling this brain box by itself. It’s out now, ready for integration into your own self-built Taz, or a 3D printer of your own design.
Speaking of the Midwest RepRap Festival, it’s only a month away. It’s scheduled for March 25-26th at the Elkhart County 4-H Fairgrounds in Goshen, Indiana. Why the middle of nowhere? It ensures only the cool kids make it. For one weekend a year, Goshen, Indiana turns into the nexus of all things 3D printing. Don’t ask questions, just come. It’s free, although it would be cool if you kicked a few bucks over to the organizers.
[Clickspring] — the guy who built a fantastic clock in his home shop – is working on his second project. It’s an Antikythera Mechanism, and the latest episode is about building a gigantic gear. This is a unique approach to building an Antikythera Mechanism. [Clickspring] is still using modern tools, but he’s figuring out how this machine was built with tools available 2000 years ago.
Ogopogo. Champ is a picture of a log and Nessie is a toy submarine with a head made out of plastic wood. Ogopogo is a plesiosaur. Are you going to tell me a log – or at best a beaver – can kick the ass of a plesiosaur? Ogo. Pogo. Plesiosaur.The Travelling Hacker Box has conquered Ogopogo.
The ESP32 is quickly becoming the coolest microcontroller platform out there. You know what that means – Kickstarters! The FluoWiFi is Arduino-derived dev board featuring the ESP32 for WiFi, Bluetooth, and all the cool wireless goodies. This board also features an ATMega644p — basically the little sister to the ATMega1284p – for all your standard microcontroller Arduino stuff. It’s £25 for a board, which makes it pretty inexpensive for what you’re getting.
I have a love/hate relationship with the crocodile clip. Nothing is so quick to lash together a few half-baked prototype boards on your desk, but nothing ends up in such a tangle so quickly, either. I love the range of pretty colors that crocodiles come in, as well as the easy ability to just clip on to the side of a PCB, or any old loose wire. But they come loose, they can have intermittent contacts, and we’re not even sure if there is such a thing as a current rating for them.
When [WarriorRocker] wrote in asking what we use instead of crocodile clips, he included a photo that sent a chill down my spine, from a review of some clips on Amazon. I’ve seen this one in real life. And what’s worse is the one with the loose wires that sometimes make contact with the spring-clip body and sometimes not.
After an hour-long debugging session about twelve years ago now, such an intermittent croc caused us to make a lifelong vow. All of our croco-clips have been disassembled, manually inspected, and many of them soldered together. When I buy new ones, I check them all before mixing them in with the known-goods. Even thinking about this now makes me want to pull back their little rubber booties just to make sure. Continue reading “Ask Hackaday: Bitten by the Crocodile Clip”→
The chat functionality on Hackaday.io is quickly turning into the nexus of all things awesome. This Tuesday, February 28th, everyone’s favorite robotic dog is talking certifications. Everything from FCC to UL to OSH to CE and the other CE is on the table. If you want to build hardware, and especially if you want to build a product, this is the talk for you. Join us for the next Tindie Chat on Hackaday.io.
Every month or so, we round up Tindie sellers, buyers, and the Tindie curious to talk about the issues facing hardware creators. We meet up in the Tindie Dog Park to talk about all things Tindie and hardware creation. If you want to know anything about certifications — whether you’re selling on Tindie or not — this is the virtual meetup for you.
This chat is going down Tuesday, February 28th at 11:00 AM PST (or 19:00 GMT). Want to join in the chat? Head on over to the Tindie Dog Park and request to join the project. Then, just head over to the chat by clicking on the ‘Team Messaging’ button. If you have a question, we have a spreadsheet.
There are a lot of experienced product designers over on Tindie, and this is a prime opportunity to learn some of the hard lessons these Tindie sellers have already experienced. Don’t miss this, it’s going to be great.
There is an old saying: “In theory, theory and practice are the same. In practice, they are not.” We spend our time drawing on paper or a computer screen, perfect wires, ideal resistors, and flawless waveforms. Alas, the real world is not so kind. Components have all kinds of nasty parasitic effects and no signal looks like it does in the pages of a text book.
Consider the following problem. You have a sine wave input coming in that varies between 0 V and 5 V. You want to convert it to a square wave that is high when the sine wave is over 2.5 V. Simple, right? You could use a CMOS logic gate or a comparator. In theory…
The problem is, the sine wave isn’t perfect. And the other components will have little issues. If you’ve ever tried this in real life, you’ll find that when the sine wave is right at the 2.5 V mark the output will probably swing back and forth before it settles down. This is exacerbated by any noise or stretching in the sine wave. You will wind up with something like this:
Notice how the edges of the square wave are a bit fat? That’s the output switching rapidly back and forth right at the comparator’s threshold.
The answer is to not set the threshold at 2.5 V, or any other single value. Instead, impose a range outside of which it will switch, switching low when it leaves the low end of the range, and high when it exceeds the high end. That is, you want to introduce hysteresis. For example, if the 0 to 1 shift occurs at, say, 1.9 V and the 1 to 0 switch is at 0.5 V, you’ll get a clean signal because once a 0 to 1 transition happens at 1.9 V, it’ll take a lot of noise to flip it all the way back below 0.5 V.
You see the same effect in temperature controllers, for example. If you have a heater and a thermal probe, you can’t easily set a 100 degree set point by turning the heater off right away when you reach 100 and then back on again at 99.9999. You will usually use hysteresis in this case, too (if not something more sophisticated like a PID). You might turn the heater off at 99 degrees and back on again at 95 degrees, for example. Indeed, your thermostat at home is a prime example of a system with hysteresis — it has a dead-band of a few degrees so that it’s not constantly turning itself on and off.
Schmitt Triggers and How to Get One
A Schmitt Trigger is basically a comparator with hysteresis. Instead of comparing the incoming voltage with VCC / 2, as a simple comparator would, it incorporates a dead band to ensure that logic-level transitions occur only once even in the presence of a noisy input signal.
Assuming you want a Schmitt trigger in a circuit, you have plenty of options. There are ICs like the 74HC14 that include six (inverting) Schmitt triggers. On a schematic, each gate is represented by one of the symbols to the right; the little mark in the box is the hysteresis curve, and the little bubble on the output indicates logical negation when it’s an inverter.
You can also make them yourself out of transistors or even a 555 chip. But the easiest way by far is to introduce some feedback into a plain op amp comparator circuit.
Below are two op amps, one with some positive feedback to make it act like a Schmitt trigger. The other is just a plain comparator. You can simulate the design online.
If you haven’t analyzed many op amp circuits, this is a good one to try. First, imagine an op amp has the following characteristics:
The inputs are totally open.
The output will do whatever it takes to make the inputs voltages the same, up to the power supply rails.
Neither of these are totally true (theory vs. practice, again), but they are close enough.
The comparator on the right doesn’t load the inputs at all, because the input pins are open circuit, and the output swings to either 0 V or 5 V to try, unsuccessfully, to make the inputs match. It can’t change the inputs because there is no feedback, but it does make a fine comparator. The voltage divider on the + pin provides a reference voltage. Anything under that voltage will swing the output one way. Over the voltage will swing it the other way. If the voltages are exactly the same? That’s one reason you need hysteresis.
The comparator’s voltage divider sets the + pin to 1/2 the supply voltage (2.5 V). Look at the Schmitt trigger (on top). If the output goes between 0 V and 5 V, then the voltage divider winds up with either the top or bottom resistor in parallel with the 10K feedback resistor. That is, the feedback resistor will either be connected to 5 V or ground.
Of course, two 10K resistors in parallel will effectively be 5K. So the voltage divider will be either 5000/15000 (1/3) or 10000/15000 (2/3) depending on the state of the output. Given the 5 V input to the divider, the threshold will be 5/3 V (1.67 V) or 10/3 V (3.33 V). You can, of course, alter the thresholds by changing the resistor values appropriately.
Schmitt triggers are used in many applications where a noisy signal requires squaring up. Noisy sensors, like an IR sensor for example, can benefit from a Schmitt trigger. In addition, the defined output for all voltage ranges makes it handy when you are trying to “read” a capacitor being charged and discharged. You can use that principle to make a Schmitt trigger into an oscillator or use it to debounce switches.
If you want to see a practical project that uses a 555-based Schmitt, check out this light sensor. The Schmitt trigger is just one tool used to fight the imprecision of the real world and real components. Indeed, they’re nearly essential any time you want to directly convert an analog signal into a one-bit, on-off digital representation.
Hackaday and Tindie will be at SCALE Friday through Sunday, showing off the coolest parts of Hackaday, Hackaday.io, and our lovable robotic dog, Tindie. We’ll be handing out t-shirts and stickers, and we’ll be giving tours of the SupplyFrame Design Lab located just two blocks away from the convention center. The Design Lab is a crown jewel of our corporate overlord’s emphasis on Open Hardware, and if you want to see where the magic happens, this is your chance. We’ll be running tours of the Lab on Friday, so find the Hackaday and Tindie crew in the expo area around 3:40 PM.