Plus Size Watch with a Pair of Tiny Nixies

When you stuff a pair of Nixie tubes into a wristwatch the resulting timepiece looks a little like Flavor Flav’s necklace. Whether that’s a good thing or not depends on your taste and if you’re comfortable with the idea of wearing 200 volts on your wrist, of course.

As a build, though, [prototype_mechanic]’s watch is worth looking into. Sadly, details are sparse due to a computer issue that ate the original drawings and schematics, but we can glean a little from the Instructables post. The case is machined out of solid aluminum and sports a quartz glass crystal. The pair of IN-16 tubes lives behind a bezel with RGB LEDs lighting the well. There’s a 400mAh LiPo battery on board, and an accelerometer to turn the display on with a flick of the wrist.

It may be a bit impractical for daily use, but it’s a nicely crafted timepiece with a steampunk flair. Indeed, [prototype_mechanic] shows off a few other leather and Nixie pieces with four tubes that certainly capture the feel of the steampunk genre. For one with a little more hacker appeal, check out this Nixie watch with a 3D-printed case.

Posted in clock hacks, nixie, steampunk, watch | Leave a comment

Brain Controlled Tracked Robot

[Imetomi] found himself salvaging a camera from a broken drone when he decided to use it in a new project, a tracked robot with a live video feed from the mounted camera.

… I had a cheap Chinese drone that was broken, but its camera seemed to be operating and when I took apart my drone I found a small WiFi chip with a video transmitter. I (decided) that I will use this little circuit for a project and I started to buy and salvage the parts.

Being a tracked robot, it can negotiate most types of terrain and climb hills up to 40 degrees. It is powered by two 18650 lithium-ion batteries with a capacity of 2600 mAh and the remote control is based on the HC-12 serial communication module. You can control it with a joystick and watch the camera’s live-stream in a virtual reality glass. That’s pretty neat but it’s not all.

[Imetomi] also used a hacked Nacomimi Brainwave Toy to make a brain controlled version of his robot. The brainwaves are detected using sensors placed on the scalp. To actually control it the operator has to focus on the right hand to move right, focus on the left hand to move left, blink to move forward and blink again to stop. There is also an ultrasonic sensor to help navigation so the robot doesn’t bump into things. It’s not very precise but you can always build the joystick version or, even better, make a version with both controls.

We covered an Arduino brain computer interfaces way back in 2009 and the suggestion we made was a brain controlled beer bot. But this is quite cool too. You can find the build instructions here. If you build one, lets us know how the brain control works for you.


Posted in arduino, brain control, FPV, live stream, robots hacks, tracked robot | Leave a comment

Multiextrusion 3D Printing and OpenSCAD

In a recent posting called Liar’s 3D Printing, I showed you how you can print with multiple filament colors even if your printer only has one extruder and hot end. It isn’t easy, though, and a lot of models you’ll find on sites like Thingiverse are way too complicated to give good results. An object with 800 layers, each with two colors is going to take a lot of filament changes and only the most patient among us will tolerate that.

What that means is you are likely to want to make your own models. The question is, how? The answer is, of course, lots of different ways. I’m going to cover how I did the two models I showed last time using OpenSCAD (seen below). The software is actually really well suited for this hack, making it easy for me to create a framework of several models to represent the different colors.

About OpenSCAD

I’m not going to say much about OpenSCAD. It is less a CAD package and more a programming language that lets you create shapes. We’ve covered it before although it changes from time to time so you might be better off reading the official manual.

The general idea, though, is you use modules to create primitives. You can rotate them and translate them (that is, move them). You can also join them (union) and take the difference of them (difference). That last is especially important. For example, look at the callsign plate above. Forget the text for now. See the two holes? Here’s the OpenSCAD that creates that shape:

 difference() { cube([basew,basel,basez]); // cut holes translate([4,basel/2,0]) cylinder(r=2,h=basez+2); translate([basew-4,basel/2,0]) cylinder(r=2,h= basez+2); }

The cube “call” creates the base. The cylinders are the holes and the difference “call” is what makes them holes instead of solid cylinders (the first thing is the solid and everything after is taken away). One key point: instead of numbers, the whole thing uses (mostly) variables. That means if you change the size of something, everything will adjust accordingly if you wrote the script well. Let’s look at applying these techniques for multiple colors.

Two Colors

To drive a printer with two extruders (or one you are lying about) you need to generate two different STL files, one for each extruder. That means that it is very likely one of them is going to be just “floating” in the air and that’s OK because, in reality, it will have the other color under it.

There are lots of ways you could accomplish this. I made a simplifying assumption: Your object will mainly be one color and then you’ll have one or more colors as part of the object. Then I wrote a simple framework consisting of several OpenSCAD modules.

In OpenSCAD, what you think of as functions are called modules. There are three modules in the framework you have to worry about: object_1, object_2, and object_3. Essentially, you put the OpenSCAD code in those modules that refer to each color you want. Here’s the code for the test box (I left object_3 empty):

module object_1() // first object, main color
{ cube([basew,basel,basez]);
} module object_2() // 2nd objects
{ translate([basew/2,basel/2-5*dotr,basez-dothi/2]) cylinder(r=dotr,h=dothi,center=true); translate([basew/2,basel/2+5*dotr,basez-dothi/2]) cylinder(r=dotr,h=dothi,center=true); translate([basew/2,basel/2,basez/2]) rotate([0,90,0]) cylinder(r=dotr,h=basel,center=true);

The first two cylinders are the top spots. They just translate up to the right spot. The third cylinder is rotated and appears in the middle of the box. Keep in mind that every layer that has a colored dot is going to take a filament change. Not a problem if you really have two extruders, but if you are lying, each tool change is some manual work as you pause and manually swap colors on your single head.

Getting the STLs

There is one more thing you have to change to get things to work. At the bottom of the framework file there are some lines that are mostly commented out:

// ********************************
// To generate, pick one of these and render (F6)
// then if you picked one of the create_* you can
// export to STL. No need to export the preview

Only one of these lines should be uncommented at any given time. When you are doing your design, leave preview_obj uncommented. This will let you see the entire object with different colors for each piece.

When you are ready to create the STL files, comment out the preview line and uncomment one of the create lines. Then render using F6 (the full render). When it completes, export the STL file and then replace the comment on the line and uncomment the next line. Then repeat the F6 render and the export. In this case, you don’t have to do object 3 because there’s nothing in it.

What Happens?

The rest of the framework is pretty simple. When you do the create on object 1, it draws your object and subtracts out all the places that should be another color. The other two create calls simply render the objects you specify. I’ve assumed that you won’t have any parts of color 2 and color 3 that intersect. If you did, you’d have to do something more complicated (that is, subtract out the third object from the second; it wouldn’t be that hard).

That’s it. If you can model in OpenSCAD you can create multiple extrusion models. If you lie, you can print them on a single extrusion printer, just like I did. I haven’t tried it, but you ought to be able to use the 2nd color to cut away overhangs, and the 3rd color to build custom support structures. Then you would simply not export the 2nd color and proceed as a normal two-color print.

Obviously, this isn’t the only way to do it. In fact, it isn’t even the only way to do it in OpenSCAD. But it is a handy way to make simple multicolor models that are suitable for use with the liar’s printing method. If you don’t want to install OpenSCAD you could try your browser or you might be able to do a similar thing with OpenJSCAD.

Posted in 3d Printer hacks, 3d printing, Hackaday Columns, multiextrusion, openscad, Skills | Leave a comment

Cheating at 5V WS2812 Control to Use 3.3V Data

If you’re looking to control WS2812 (or Neopixel) LEDs using a microcontroller running at 3.3 volts, you might run into some issues. The datasheet tells us that a logic high input will be detected at a minimum voltage of 0.7 * Vcc. If you’re running the LED at 5V, this means 5 V * 0.7 = 3.5 V will be needed for the WS2812 to detect a ‘1’ on the data line. While you might get away with using 3.3 V, after all the specification in the data sheet is meant to be a worst case, it’s possible that you’ll run into reliability issues.

So usually we’d say “add a level shifter to convert 3.3V to 5V” and this post would be over. We even have a whole post on building level shifters which would work fine for this application. However [todbot] at CrashSpace came up with a nifty hack that requires fewer components yet ensures reliability.

bigbutton-front-backFor the Big Button project at CrashSpace, [todbot] used an ESP8266 running at 3.3 volts and WS2812 LEDs running at 5 V. To perform the level shift, a signal diode is placed in series with the power supply of the first LED. This drops the first LED to 4.3 V, which means a 4.3 V * 0.7 = 3.01 V signal can be used to control it. The logic out of this LED will be at 4.3 V, which is enough to power the rest of the LEDs running at 5 V.

This little hack means a single diode is all that’s needed to control 5 V LEDs with a 3.3 V microcontroller. The first LED might be a little less bright, since it’s operating at a lower voltage, but that’s a trade off [todbot] made to simplify this design. It’s a small part of a well-executed project so be sure to click-through and enjoy all the thought [todbot] put into a great build.

Posted in ESP8266, led hacks, level shifter, ws2812 | Leave a comment

Hackaday Dictionary: Open- and Closed-Loop Systems

Today on Hackaday Dictionary, we’re going to talk about the two basic types of control systems: open-loop and closed-loop. We’ll describe the differences between them and explore the various advantages and disadvantages of each. And finally, we’ll talk about what happens when you try to draw a line between the two.

light-switch-okAnd there was much rejoicing. Image via Racoon Valley Electric Cooperative

Control Systems

Control systems are literally all around us. They’re illuminating our rooms, laundering our unmentionables, and conspiring to make us late for work. Most of us probably use or interact with at least five control systems before we’re even out the door in the morning. Odds are you’re using a control system to read this article.

When we say ‘control system’, we’re speaking broadly. A control system is defined as any system that exhibits control over a function. It doesn’t matter how big or small the function is. A standard light switch is a simple type of control system. Flip it back and forth and the light is either on or off with no in between. Too bright? Too bad. There is no way to account for light intensity preference, use duration, energy output, or anything else.

speed-queenA humble clothes dryer. Image via Showplace Rents

Another common example in discussing control system theory is the clothing dryer. Set the timer on the dryer and it will run until time expires. Will it run long enough to dry everything without shrinking anything? The only way to know is to open the door and check.

Both the light switch and the clothes dryer are open-loop systems. The process is a straight line from start to finish, and they operate without concern for their output. Once the light switch is flipped to the on position, current will flow until the switch is reversed. The switch doesn’t know if the bulb is burned out or even screwed into the socket to begin with. And the clothes dryer doesn’t care if your clothes are damp or dry or totally shrunken when time runs out.

Stay in the Loop

In a closed-loop system, the process begins the same way it does in an open-loop system. But a closed-loop system has one or more feedback loops in place that can adjust the process. Sometimes the feedback will simply cause the process to repeat until the desired result is achieved.

Both of our open-loop control system examples above could easily be converted to closed-loop systems. A more advanced light switch might take input from a photo cell, or it could poll a motion detector and turn the lights off after a period of no detectable activity in the room. The clothes dryer could be improved with the addition of a moisture sensor. Since the humidity level in the dryer will change during the cycle, why not poll a DHT22 and re-run the process until a predetermined humidity level is reached? Then the dryer becomes a closed-loop system. No more reaching in and fondling the towels and shirt collars to make sure everything is dry. Well, at least in theory.

xkcd_traffic_lightsWhat are they telling you? xkcd #1116

Some control systems exist in both forms. Traffic lights are a good example of this phenomenon. Some lights are open-loop and simply run on a schedule. Many more of them are closed-loop and will cycle differently depending on traffic flow or information received from other traffic lights. The really smart ones have Emergency Vehicle Preemption (EVP) receivers. This is the system that allows fire trucks and some other emergency vehicles to change the lights in their favor. A device in the vehicle strobes a specific pattern at the receiver module on the light post, and the light changes as soon as possible.

cruise-controlCruise control via Wikipedia

Advantages and Disadvantages

The main advantage of closed-loop systems is fairly obvious: using feedback means more and better control. But there are trade-offs. It’s almost impossible to deal with all the what-ifs in creating any system, and this generates unforeseen issues. They aren’t all bad, though. Maybe you’re sitting peacefully in the corner engrossed in a book, and the motion detector-driven lights shut off because you aren’t moving around enough.  That isn’t ideal, but it’s easy enough to turn the lights back on and keep reading.

The unforeseen issues can be so much worse than sudden darkness. Case in point: robotic vacuum cleaners. Here you have a complexly closed-loop system to take care of one of life’s drudgeries. Should be awesome, right? Yes, but because it is blind to everything but its pre-programmed boundaries, it doesn’t know not to spread messes around.

A lot of closed-loop control systems look great on paper, but their imperfections become clear in execution. Take cruise control for example. Here is a system that’s better at its job than humans are. It will maintain the set speed until you hit the brakes or run out of gas. It will perform as intended whether there is a headwind or a tailwind or you’re towing a boat or transporting rowdy children. But cruise control isn’t aware of cliffs or guard rails or deer darting out in front of the car. Cruise control keeps its head down and does its job until it can’t go on.

Open-loop systems may not be as smart as closed-loop systems, but they often shine in their simplicity. For the most part, they do what you expect them to do. Light goes on, light goes off. And they are arguably more dependable since there are fewer things that can go wrong. Of course, a “simple” open-loop control system can mean a steeper learning curve. It’s not easy to learn to drive a manual transmission. But if you don’t know how to drive one, you’re missing out on some nice advantages, like the ability to push start the thing if you have to, and the option to downshift instead of pumping the brakes in icy conditions. So the question is this: is an open-loop system more valuable than a closed-loop system if it means having more control over the process? Does it depend entirely on the process in question?

tricycle-door-stopperThis tricycle is simultaneously safe and unsafe. Image via Apple Door

Open-Loop vs. Closed-Loop

So where exactly does open-loop end and closed-loop begin? The line seems clear for some systems, but muddy for others. How much feedback is enough to qualify? Add just about anything to a light switch and it seems safe to say that you took it from open- to closed-loop.

More often than not, the line between the two is blurry. Think of a motorized garage door.  You push the button and the door either opens or closes. Push it again and the door moves in the opposite direction. Most modern garage doors have a fail-safe in place to stop the garage door in the event of an emergency. If the door encounters any resistance, it will stop and reverse direction.

The break beam detector is supposed to keep people and their tricycles from being crushed if they happen to be in the way while the door is closing. But it only works if the person or thing breaks the IR beam. There’s only one beam, and it sits about six inches off the floor. The motorized garage door system is actually quite limited because it has no positional awareness. It doesn’t know where it is on the track, it’s just going up and down blindly, waiting for input or resistance.

Not all doors can be counted on to stop if they feel resistance—I tested mine and it kept on going. So if I don’t pull far enough into the garage and then put the door back down, it might hit the protruding rear end of my hatchback. It’s in the way of the door closing, but it sits way too high to break the beam. So is the garage door really, truly a closed-loop system?

Posted in break-beam detector, closed loop, clothes dryer, control system, Hackaday Columns, Hackaday Dictionary, open-loop, traffic light | Leave a comment

DIY Thermal Imaging Done Low-Tech Style

[Niklas Roy] has always wanted to try out thermal imaging and saw his opportunity when he received one of those handheld IR thermometers as a gift. But not content with just pointing it at different spots and looking at the temperatures on the LCD display, he decided to use it as the basis for a scanning, thermal imaging system that would display a heat map of a chosen location on his laptop.

DIY thermal imaging systemDIY thermal imaging system

He still wanted to to be able to use the IR thermometer as normal at a later date so cutting it open was not an option. Instead he firmly mounted a webcam to it pointing at the LCD display. He then wrote software on his laptop to process the resulting image and figure out what temperature was being displayed.

Once he got that working, he next put the thermometer on a platform with servos connected to an Arduino for slowly rotating it in the horizontal and vertical directions, also under control of the software on his laptop. Each time the thermometer measures the temperature of a spot, the software decodes the temperature on the LCD display and then tells the Arduino to use the servos to point the thermometer at the next spot to be measured. Each measurement takes a little time, so scanning an entire location as 70×44 spots takes around a half hour. But the end result is a heat map drawn on the laptop, done by a device that is low-tech. [Editor’s Snark: Because attaching a webcam and processing the images is “low-tech” these days.] He can overlay the heat map on a normal photo to see at a glance where the hot spots are.

The software he wrote is available on GitHub and the video below shows it in action. We’ve got to admit, it’s pretty awesome to watch. You can even see the heat map being filled in one measurement at a time.

[Niklas] is somewhat of a regular here on Hackaday and his projects span an impressive range of creative ideas. Check out his massive music construction machine, or his RC beer crate delivery robot, or his supersized DIY pinball machine. Whatever you do [Niklas], keep those creative juices flowing!

Posted in arduino, IR thermometer, misc hacks, thermal imager, thermal imaging | Leave a comment

Autodesk Moves EAGLE to Subscription Only Pricing

EAGLE user? We hope you like subscription fees.

Autodesk has announced that EAGLE is now only available for purchase as a subscription. Previous, users purchased EAGLE once, and used the software indefinitely (often for years) before deciding to move to a new version with another one-time purchase. Now, they’ll be paying Autodesk on a monthly or yearly basis.

Lets break down the costs. Before Autodesk purchased EAGLE from CadSoft, a Standard license would run you $69, paid once. The next level up was Premium, at $820, paid once. The new pricing tiers from Autodesk are a bit different. Standard will cost $15/month or $100/year, and gives similar functionality to the old Premium level, but with only 2 signal layers. If you need more layers, or more than 160 cm^2 of board space, you’ll need the new Premium level, at $65/month or $500/year.

New Subscription Pricing Table for EagleNew Pricing Table for EAGLE

This is a bad deal for the pocket book of many users. If you could have made do with the old Standard option, you’re now paying $100/year instead of the one-time $69 payment. If you need more space or layers, you’ll likely be up to $500/year. Autodesk also killed the lower cost options for non-commercial use, what used to be a $169 version that was positioned for hobbyists.

The free version still exists, but for anyone using Eagle for commercial purposes (from Tindie sellers to engineering firms) this is a big change. Even if you agree with the new pricing, a subscription model means you never actually own the software. This model will require licensing software that needs to phone home periodically and can be killed remotely. If you need to look back at a design a few years from now, you better hope that your subscription is valid, that Autodesk is still running the license server, and that you have an active internet connection.

On the flip side of the coin, we can assume that Eagle was sold partly because the existing pricing model wasn’t doing all it should. Autodesk is justifying these changes with a promise of more frequent updates and features which will be included in all subscriptions. But sadly, Autodesk couldn’t admit that the new pricing has downsides for users:

“We know it’s not easy paying a lump sum for software updates every few years. It can be hard on your budget, and you never know when you need to have funds ready for the next upgrade.”

In their press release, they claim the move is only good for customers. Their marketing speak even makes the cliche comparison to the price of a coffee every day. Seriously.

[Garrett Mace] summarized his view on this nicely on Twitter: “previously paid $1591.21 for 88 months == $18.08/mo. Moving to $65/mo? KICAD looks better.”

We agree [Garrett]. KiCad has been improving steadily in the past years, and now is definitely a good time for EAGLE users to consider it before signing on to the Autodesk Subscription Plan™.

Posted in autodesk, cadsoft, eagle, KiCAD, news, pricing, subscription | Leave a comment

Steve Collins: When Things Go Wrong In Space

[Steve Collins] is a regular around Hackaday. He’s brought homebrew LIDARs to our regular meetups, he’s given a talk on a lifetime’s worth of hacking, and he is the owner of the most immaculate Hackaday t-shirt we’ve ever seen.

For the 2016 Hackaday SuperConference,  [Steve] took a break from his day job of driving spacecraft around the Solar System. As you can imagine, NASA plans on things going wrong. How do you plan for that? [Steve] answers all your questions by telling you what happens when things go wrong in space.

Space is the worst possible place for hardware. Not only do you have temperature swings of hundreds of degrees, solar radiation, and limited bandwidth, but you also can’t fix a space probe once it’s in orbit. Anyway you look at it, everything needs to go perfectly or you need to be exceptionally clever. Muphry’s Law will inevitably crop up to defeat the former, leaving the latter par for the course. This is what it’s like to work at the Jet Propulsion Lab.

Most satellites that go up are, surprisingly, very standardized. GPS satellites are built around a two or three common ‘busses’, or models. When a company wants to launch a few dozen communications satellites, the first one-off the pad won’t be much different from the last. Whenever SpaceX gets around to launching four thousand of their low orbit Internet satellites, all of those birds are going to be the same.

Deep space satellites are completely different. Each one is a custom build, and the best examples of twin deep space probes – Spirit and Opportunity on Mars, and Voyager 1 and 2 – are the exception rather than the rule. A unique piece of hardware flying around the Solar System presents a few challenges for the hardware designers. Power is always an issue, you need to plan for redundancy, and every piece of hardware needs some sort of fault protection system. Everything is a challenge in designing a deep space probe, and you need to plan for every contingency.

This is the theory of designing hardware that has to work perfectly in the worst environment imaginable, but how about some practical examples of what to do when things go wrong in space?

Throughout [Steve]’s storied career, he’s been a part of a lot of NASA missions. In the 90s, one of his jobs was planning the Deep Space 1 mission. This was a mission to a comet done on the cheap — only about $150 Million – used to demonstrate up and coming technologies like ion propulsion. While in the planning stages, [Steve] and his colleagues discussed what could go wrong. Since this was a very inexpensive mission, only one star tracker was flown on this tiny satellite.

This star tracker is important, as it’s the only thing on the spacecraft that tells the computer where it’s pointing. In the planning stages, [Steve] discussed what would happen if that star tracker died. The hypothetical solution to this problem used the science camera to point at a single star and determine the probe’s orientation. This solution sat around in the back of [Steve]’s mind for a few years until — you guessed it — the star tracker died. It wasn’t pretty, but the hack of using a science camera to determine the spacecraft’s orientation worked.

That’s a sample of what happens when things go wrong in space. What happens when things go right? Check out the video below. That’s a car, landing on Mars, with the help of a rocket-powered crane. It’s Curiosity dropping into Gale crater, and [Steve] was in the control room for this astonishing feat of engineering. He’ll be doing it again in late 2020, and with this guy at the helm we shouldn’t have much to worry about.

Posted in 2016 Hackaday SuperConference, cons, Featured, nasa, repair hacks, space flight, space probes, Steve Collins, troubleshooting | Leave a comment

Relay Computing

Recently, [Manuel] did a post on making logic gates out of anything. He mentioned a site about relay logic. While it is true that you can build logic gates using switch logic (that is, two switches in series are an AND gate and two in parallel are an OR gate), it isn’t the only way. If you are wiring a large circuit, there’s some benefit to having regular modules. A lot of computers based on discrete switching elements worked this way: you had a PCB that contained some number of a basic gate (say, a two input NAND gate) and then the logic was all in how you wired them together. And in this context, the SPDT relay was used as a two input multiplexer (or mux).

In case you think the relay should be relegated to the historical curiosity bin, you should know there are still applications where they are the best tool for the job. If you’re not convinced by normal macroscopic relays, there is some work going on to make microscopic relays in ICs. And even if they don’t use relays to do it, some FPGAs use mux-based logic inside.  So it’s worth your time to dig into the past and see how simply switching between two connections can make a computer.

Mux Mania

How do you go from a two input mux to an arbitrary logic gate? Simple, if you paid attention to the banner image. (Or try it interactive). The mux symbols show the inputs to the left, the output to the right and the select input at the bottom. If the select is zero, the “0” input becomes the output. If the select is one, the “1” input routes to the output.

Obviously, a relay with two poles can act like two gates (the input at the bottom has to be the same for both gates). You can also work out a buffer (swap the inputs of the NOT gate), or A OR NOT B and A AND NOT B.

It is also possible to do things like “wired OR” with relays. For example, suppose you had ten AND gates made like the one above. If you want to OR the outputs together, you just connect the output wires. Any one (or more) AND gates triggering will drive the output high. Or, you could let ground be a 1 and float highs. This has the advantage of working better with ICs and other circuits that can sink more current than they can source. Then the relay coils are always hooked up to the positive supply and you need the ground to complete the circuit.

There are other tricks you can use. Diodes can handle some simple logic functions, although this may be considered cheating if you are trying to make a true relay computer. Resistors can convert normal relays into latching relays, as can extra contacts. If you do make both logic levels actual voltages, you can play tricks with feeding both sides of the coil.  This makes a great XOR circuit–think about it. It is even more straightforward to create XOR if you don’t mind using two relays. Many modern demonstration relay computers bite the bullet and use semiconductors for memory and control circuits.


This isn’t just in the realm of theory. Many relay computing devices were built in the last century. There are several modern examples, too, although they are mostly for show, not practical devices. There is a good looking 8-bit computer, for example, that only uses 83 relays. Watch it go in the attached video. In all fairness, though, it does use semiconductors for memory and the front panel. However, the architecture write up is quite illuminating, even if you don’t want to build the computer yourself. You can see a video of it in action below.

[Paul] has a project over on that refuses to use diodes for logic and has a whopping 32-bits of memory. To save relays, he uses a 1-bit ALU. There are quite a few others out there including [Simon Winder’s] impressive build to compute square roots with a telephone dial (see video below).

We’ve covered some other cool  relay builds in the past, including this 8-bit marvel that uses 152 relays and reads its programming from paper using optical sensing. There’s also this much larger computer that even has its own online simulator.

Go For It!

If you’ve ever thought about building a computer with relays, this should give you plenty of inspiration. Just keep in mind that relays are deceptively simple: they are non-ideal devices made of coils and strips of spring steel. For example, arcing across contacts is bad, right? Depends. Some contact material depends on arcing to clean corrosion. Others just pit and fail. There’s a lot of subtlety to relays and a lot of their perceived unreliability is really just misapplication. Not that they are as reliable as modern semiconductor devices, of course, but well-made relays with the proper construction for their intended application can be pretty reliable.

Posted in Engineering, Hackaday Columns, logic, logic gates, misc hacks, mux, relay, relay computer, relays | Leave a comment

3D Printer with Tilted Bed

[Oliver Tolar] and [Denis Herrmann], two students from the Zurich University of Applied Sciences (ZHAW), designed and produced a 3D printer prototype that has a movable printing bed that can tilt. By tilting, objects with critical overhangs can be printed without the additional support material. The printer has six axes, three axes control the print head as usual and three other axes control the printing bed, allowing a wider range of movements.

The students claim that besides saving on the support material this printer can actually save time while printing objects that need a lot of support since, we assume, it’s faster to tilt the bed than to print the support itself. In normal 3D printers the plate is always horizontal and the print object is built up in horizontal layers. In this printer, for large overhangs, the printing bed is held in such a way that the print object is pivoted until perpendicular to the print head. Of course, for round shapes it will probably be different but we only saw it in action in one demonstration video. There is also the plus side that, when a print finishes, it’s finished. No x-acto knife to remove support, no sand paper, no time wasted.

Having the software controlling the bed properly was more difficult than the assembly of the printer, they said. It is still under development as it cannot, for example, simultaneously move the print head and printing bed to produce a continuous print.

It looks cool and we wonder… how much speed up can we get from such printers? How much will be the extra cost and will it be worth it?


Posted in 3d printer, 3d Printer hacks, tilted bed | Leave a comment