Tindie

Randomness is an interesting concept. If you were to flip a coin or roll dice, you’d expect random results. However, there is some nearly undetectable bias based on the construction of these objects and the person doing the flipping/rolling. The same concept applies to computer systems, which need to create random numbers for encryption and other functions.

In order to obtain random values, computers can keep a “pool” of random values to use as needed. In the Linux operating system this pool is only 4 kiloBytes in size, and is replenished using external sources such as keyboard timings and mouse movements. When used, this pool has to be replenished, which can take time.

If you need more randomness in your computing, the TrueRNG V3 USB number generator produces more than 400 kilobits per second of true random numbers. This can fill up the Linux entropy pool extremely quickly, allowing you to run applications for security, gaming, or simulations without delay.

A Random Pattern Generated with TrueRNG

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Regan’s NAS case cooling fan duct

Yes, that’s right, “Patshead.com” has a Tindie store. I’ve been following him on Twitter for a while and thought that anyone using a spinning head as his Twitter icon had to be worth getting to know. When I pinged him for an interview, he let me know that he’d be interested in an interview, but was, “A little worried that [he’d] be completely the opposite of the average Tindie user.” Obviously was going to be interesting!

First of all, I needed to know where Pat’s head came from.

I don’t remember all the exact details.  A bunch of us from work used to sometimes gather at a bar/restaurant that was between two of our offices.  This was back in ’99 or 2000.  We somehow get very excited about the idea of turning my head into a spinning gif, and we got the idea that I should register patshead.com.  For most of its life, patshead.com just hosted my email, some makeshift photo galleries, and a page with not much more than my spinning head.

I still get terribly excited when a website or social media network spins my head.  I’m still grandfathered in with an animated gif on Twitter.  Our makerspace, TheLab.ms in Plano, is very active on Meetup, and our pages on Meetup are often teeming with tiny spinning heads.  When new people show up in person, I often hear, “I recognize you!  You’re the spinning head on half of the Meetups!”

Though perhaps a little offbeat by “normal” standards, Pat seems like exactly the type of person that might sell on (or write for) Tindie. How is he different from the average Tindie user?

I’d probably be happier if no one ever bought anything from my Tindie store!  Everything in my store is a 3D printed object that I designed.  All the designs are Open Source.  I’d much rather see people print their own, or find a local makerspace that can help them out.

I wasn’t selling anything for a long time, but I regularly had people reach out to me asking where they could acquire one of my breadboard vises.  I don’t want to be in the business of manufacturing, but I quite enjoy the idea of real people making use of the stuff I design.  With the breadboard vise, I tell people that this is too much money to pay for $1.25 worth of ABS plastic.

Regan’s breadboard spring vise

Talk about a low-pressure sales pitch! So if you want something from Regan’s inventory, just print it yourself. On the other hand, if you don’t want to do that, Tindie presents another alternative!

Since you’re probably wondering:

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I’m a huge fan of electronic music and the colorful “blinky” musical instruments that produce it. On the other hand, I generally don’t have the patience that it takes to truly master one of these devices, or even get enough use out of it to be worth the purchase price. Fortunately, there are all kinds of apps available that can help fill this need at a low or free price.

On the other hand, it’s hard to beat an actual purpose-built object. Even as software tools become better, we see dedicated hardware jumping to fill new roles. A great example of this is the monome, a grid of buttons, each hiding its own LED. It’s obvious use is as a looping controller, but since it appeared, it has been used for a myriad of live-music control tasks.

Here’s a MIDI device that uses an Arduino as the brains of the operation, with 16 WS2812B RGB LEDs to make the pads light up as needed. With just a four by four LED grid, it might be a bit more accessible for novices like myself. If you give it a whirl and decide it’s no longer useful, you could reprogram it to do something different, or perhaps turn the parts into something else!

Personally, I could also see something like this as an amazing robot controller (if you need a backup plan to justify it). On the other hand, it appears to do the job it was designed for—making electronic music—quite well, as seen in the video below.

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The Original Sinclair ZX80. Photo By Daniel Ryde, Skövde
Originally from the Swedish Wikipedia., CC BY-SA 3.0

Today, if you want a very inexpensive computer, you may think of the Raspberry Pi or perhaps even the CHIP. At well under $50, these boards can run Linux and do some really amazing things given their price tag. If you want one in a case of some sort, or even a keyboard, you have to add that on yourself. You’ll have a computer but it’s not going to perform like the best PCs on the market. But perhaps that’s not the point.

It’s a great time for computer hacking, and it so unique that we can get something set up with these single-board computers for such a reasonable price. But ask yourself, is it actually all that “unique?”. You may be surprised to learn that the ZX80 computer, from Sinclair Research was available in the UK in 1980 for under 80 pounds in kit form. Unlike the ‘Pi, it even included a keyboard!

Minstrel ZX80 Clone

Admittedly, that price works out to around 300 pounds (roughly $360 US) in today’s currency, but it’s still a pretty neat achievement. Unfortunately, the computer did have its drawbacks, including the fact that the screen would blank out when doing any processing work. Also, there were overheating issues, but even with all that it still sold 100,000 units, introducing many to the world of computing.

If you’d like to be (re)introduced to this marvel of old school computing, You can find the Minstrel ZX80 clone in an original, lightly refurbished, ZX81 case on Tindie. The most noticeable difference is that it can output video signals to a modern TV!

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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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