Tindie

If you’ve ever noticed how the sound of a fire truck’s siren has a higher pitch when it approaches you than when it moves away, this is due to the Doppler effect. In this case, when the vehicle is approaching you at a high speed, the number of sound wave that reach your ear over a period of time is increased. When it moves away, that number is then decreased. The actual wave frequency hasn’t changed, but your frame of reference has.

A Doppler sensor takes this somewhat interesting concept and turns it into useful information about a moving object’s speed relative to it. There are some pretty inexpensive ones to be found on eBay — like the CDM324 module — but they’re not more easily available than that yet. It seems these CDM324 modules do require a bit more circuitry for operation.

It’s becoming a rule that if you can find a cheap sensor, there’s a breakout board somewhere to make it easy to use. As outlined in his build writeup, Stephan Electronics has taken care of this extra circuitry in a tiny 3D-printed package. This module gives you a reflected frequency output to tell you a subject’s speed, as well as a voltage output proportional to the reflected signal’s strength. The result is very reliable sensing from this Doppler module despite somewhat lacking details in the OEM’s datasheet. See for yourself below.

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Today’s inspiration comes from outside the Tindie universe, via the “Meed” robot, which is currently in development by Pollen Robotics. The prototype is made in such a way that they hope to quickly iterate the designs, and invite people to comment on what they like or dislike about it.

What I thought was especially interesting, and perhaps inspirational for those interested in selling their own robots, was it’s double-servo leg system shown at 1:45 in the video below. These two servos, using additional linkages reminiscent of a scissor lift, allow it to place the ends of its appendages in a wide variety of positions.

Besides this vertical leg configuration, this type of setup could also be applied in a horizontal plane to make a robotic arm. This could move a gripper or other tool around, similar to a gantry or SCARA robot system. In fact, the principle is reminiscent of how a polar plotter works, one of which was featured here recently.

Even though Tindie has quite a few robots available, I don’t think I’ve seen any using this particular kinematic configuration. Perhaps it could be inspiration for your next ‘bot!

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NODE’s original Linux terminal

Today’s interesting device comes to us from none other than “NODE,” or “N-O-D-E,” who in true hacker fashion prefers to keep his true identity a mystery. We can surmise that he is indeed male, and perhaps hails from somewhere in the British Isles.

Regardless of personal details, his original handheld Linux terminal is a beautiful piece of portable engineering, featuring a Raspberry Pi A+ along with a 2.8″ touchscreen  and a 500mAh battery. All of this is housed in two 2.5 inch hard drive enclosures that fold together to make a Nintendo DS-style portable that acts as a tiny terminal.

Version 2 of NODE’s Linux terminal

Of course this little terminal wasn’t the end of his experiments, and he made something quite similar seen in the image directly above, and in this video. He even followed it up with a third device, seen in the video below, using a sliding keyboard and a Raspberry Pi Zero W, forgoing the clamshell design.

So how does this tie in with Tindie? Well another clue to Node’s identity is that he’s at least heard of Tindie, stating that he may use a larger screen, such as this one listed here, in a future version. Though he didn’t actually use that screen in his second or third version, perhaps what he listed will pop up in a future version of one of his builds!

Find Tindie products or references in the “wild?” Hit up Tindie’s Twitter handle to let us know!

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It seems like hacker/maker/hobby electronics have made leaps and bounds in the last 10-15 years. On the other hand, one annoying problem still remains. Once you’ve made your project functional, it’s not always easy to you make it look finished with some sort of enclosure, especially while still connecting things to the outside world.

Here’s an interesting take on Arduino Uno cases. Bring your own Uno to party and the screw terminal shield will take care of all the external connections. The clear box features a door on the top that gives easy access to those terminals, as well as an opening on one end for a 12-pin IDC cable that breaks out your external hardware connections. The pins can be configured however you like. If that doesn’t work for your project, there’s a hole in the back that you can feed wires through which can then be secured to the board via holes for zip ties.

It’s called the “Connect and Contain Kit” which certainly isn’t overselling its features. If you’re not going to roll your own board, at least make your long-term builds robust with something like this.

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Infrared signalling, for better or worse, is the de facto standard for remote control of home appliances. Simple and cheap, though limited in range and to line-of-sight, it makes sense in many situations. Though other forms of control are becoming more common with various smart home technologies, there are many pieces of both legacy and new equipment that use this control scheme.

If you’d like to interface with “normal” equipment via a microcontroller, simply plugging in an IR LED to a microcontroller development board can work. For something a little more refined, the SendIR module is designed to help you output high quality IR signals. This unit can be powered via your microcontroller’s supply or externally (2.5V to 5V), and will work with a single or dual LED emitters as needed.

It’s a nice little breakout for dependable prototyping hardware. The board hosts constant current drivers for the IR LEDs. It also includes a surface mount visible light LED so that you can see when data is being transmitted. Jumpers select between 3.3 V and 5V operation, as well as three different transmit power levels.

If you need other infrared parts, the Analysir Tindie store has quite a few other components available, including an IR starter kit, and an IR learning module. They even have a “Silver Bullet” device — a BNC connector with an IR receiver that allows you to read IR signals directly with an oscilloscope.

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In a recent project of mine involving an Arduino Nano and a hobby servo, I found that it wasn’t able to supply sufficient power via the board’s 5V pin. Though this might seem obvious to those with more experience using this board, I thought I could get away with it, but found the results to be quite inconsistent.

Since I didn’t really want to fool with a full breadboard in my very limited space, what I decided to do was use a normal USB breakout to power the servo, then wired another very short USB cable to the board (shown above and at 0:45 in the video below). Maybe there is some reason I shouldn’t do this, but I really thought one would be available on Tindie or elsewhere.

After doing a post on USB breakouts available on Tindie and even one on the more “exotic” types available, I’ve seen a lot of breakouts, and this seems like a real opportunity. For that matter, I’m sure there are other types of breakouts, or “break-ins,” going from connector to terminals and back, that are hard to find.

If you have something you think someone on Tindie should start making/selling, and you don’t want to do it yourself, be sure to give us a shout out on Twitter; maybe we can help get the word out for you!

Or just let us know if what I proposed has some drawback I’m just not seeing.

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With all the talk about the Internet of Things and how now/soon you can control everything with your smartphone, to many people, actually setting something like this up with a device that’s not built for remote control isn’t that easy. Perhaps you’re familiar with setting up an IR emitter/receiver to do your bidding, or even more advanced IP solutions. But at the same time, if you’re just starting out, this isn’t exactly trivial.

One clever solution is the WonderBeeps. This little guy is able to take sound signals from any source, including via this iPhone application. It can then respond with one of 16 outputs. Sound signals are transmitted at 8Khz, so humans, for better or worse, can hear it. This concept is actually used in several consumer products, like the Amazon Dash Button for getting the hardware onto your WiFi network from a smartphone. WonderBeeps brings that functionality to anything you can build.

I could see quite a few interesting applications for something like this. The WonderBeeps listing mentions syncing a video art project to activate other devices—perhaps a robot or two. It would seem that you could also pull off very long distance control with any television application that “mirrors” sound from your device on your TV, and there are probably many other control schemes that aren’t immediately obvious for this type of technology.

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Did you know a Tesla coil is an electrical resonant transformer circuit? Of course you didn’t… you know it as the thing that makes big sparks, can sing a tune in a hair-tingling way, and lets you perform the Uncle Fester trick of illuminating a light bulb without it being plugged into anything. They’re awesome and you need to understand a lot of electron theory to fabricate one from scratch.

If you want to beef up your mad scientist credentials, then a Tesla coil is a great device to have in your laboratory garage. Building is the best way to show your prowess, but Bluer has a kit to put a Tesla Coil on your bench right now.

As seen in the video below, this coil doesn’t appear to make excessive visual sparks as you might have seen in movies or in a museum. On the other hand, it does turn on a variety of lights, and emits a small spark from the top—still pretty neat. And I couldn’t help but chuckle when the video narration mentions “the camera will mess up” if he gets any closer.

As of this writing, there’s not much description on the unit’s listing. Looking at the smaller Tesla coil sold by Bluer, however, there’s a pretty heavy disclaimer on there, including that you shouldn’t use it to replace conventional lighting, and that it can be a fire hazard. Obviously caution is needed any time you’re dealing with high voltage electronics.

There’s another reason to be careful. If you get into simple Tesla Coils, your interest might escalate until you have an outdoor installation that plays House of the Rising Sun.

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Would you like a robot arm? Of course you would, however, there’s this pesky problem of either paying thousands of dollars for an industrial model, or spending hundreds of hours designing and building your own. And even if you do manage to build your own, it probably undoubtedly won’t work as well as the FANUC or ABB model you’d really like to have.

There have been a few hobby-level robot arms to hit the market in recent years. One that comes to mind is the MeArm, a small offering built from acrylic and powered by tiny 9g hobby servos. Those servos are just passable for functional robotics, what you really want is a motor upgrade.

Check out the 3 degree-of-freedom (DOF) arm kits from I-Make-Robots. It moves away from the direct-drive hobby servos and brings out gearing and NEMA17 stepper motors. These are the type of motors used in many 3D printers and make this quite robust for a hobby level ‘bot. As shown in the video below, it’s able to write “HELLO WORLD” in the same place three times, showing off this wooden bot’s repeatability. On the other hand, when the speed is turned up too high at 1:55, things become entertainingly unstable.

If this seller looks familiar, we featured their Makelangelo Polar Plotter, another build that utilized the NEMA17 motors.

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You’ve probably heard about LED cubes in one form or another. If you’re like me, they’ve always seemed like an interesting project, but they’re complex and do you want to commit to all of that soldering?

The Teknoid cube employs some interesting workarounds. Those bent on bootstrapping their own RGB LED cube will be well-served by studying the assembly method employed here. Instead of a huge interlinked cube, this uses vertical columns formed from the LED leads themselves and doesn’t require soldering from one tower to the next.

The device, which measures 100mm x 100mm x 100mm (or about 4″ x 4″ x 4″) when assembled, uses the Charlieplexing technique to control all it’s 64 LEDs. Each tower of four LEDs stands on its own. The four leads (R, G, B, and ground) of each LED are bent to four sides of the LED and are soldered to the “shoulder” of the leads for the LED below it. Teknoid doesn’t specifically describe the assembly pattern but that’s a fun exercise for the reader to work out. Presumable the Charliplexing is accomplished by rotating each pixel 1/4 turn or more than the one below it.

When assembled it can make several interesting light patterns. It can also detect music, using a low pass filter to allow it to light up along with the music’s bass. You can see a demonstration of these animations in the video below. The flashes starting at around 1:15 are especially entertaining, and you can see how it reacts to a knocking sound at around 2:15.

For another semi-DIY LED cube (involving quite a few more LEDs), be sure to check out the 8 x 8 x 8 jolliCube, or Tindie’s blog writeup on it here.

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