Tindie

As a kid, you probably played a game called “Connect Four,” where you drop your colored cylinder into a slot with the goal of connecting four pieces. This “Four in a Row” game is played in much the same way, with one big difference. Neither side’s pieces are colored, but are instead clear acrylic disks.

As shown in the video below, once a disk is dropped into a slot, the game recognizes this and lights it up in your color. It’s programmed to recognize and highlight a win, and even allows you to reposition a disk if you make a mistake. If that weren’t enough, when the game is not being played, it acts as a customizable scrolling text display.

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As you probably know, this isn’t the only thing that can be made out of acrylic and RGB LEDs. The Est store also lists in “Interactive light effect tower,” which appears to be fun for all ages. The light pattern can be changed via three infrared sensors, and it can act as a three-dimensional audio view meter.

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Measuring pulse is a tricky business due to the low amplitude of the signals involved which are usually only a few milli-volts. Photoplethysmogram (PPG) is a method of detecting pulse which works using an IR LED and an IR photo-detector. IR light is shone into the skin and the amount reflected back changes as the blood pulses through the body.

The signal from the photo-detector needs to be amplified before it can be effectively sampled by an Analog to Digital Converter like the ones found in most micro-controllers. This is where the Easy Pulse Plugin steps in to save the day. It uses the MCP6004 Quad Op Amp made by Microchip for amplification. From reading the documentation page, it’s clear that a lot of work has gone into the circuit design to get the cleanest possible signal out. The board is also Arduino compatible, designed to plug directly into an Arduino’s header pins. It can also be plugged into a breadboard for use with whatever microcontroller you work with.

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Unless you’re already in the know, “Tindie” is perhaps a term you’re not really that familiar with. Though I had a passing familiarity of it as sort of an Etsy platform for electronics, before I started writing here, I didn’t really know what kind of things were sold and who was selling. After a month or so of browsing, perhaps I can help fill you in.

How Did it Start?

As seen in the video below, founder Emile Petrone noticed a steady uptick in Arduino and Raspberry Pi interest. In 2012, he put the question out there: would people support a marketplace for custom electronics? From that humble idea came the idea for this site.

As far as the name, per this interview, it’s derived from “Indie Tech” and “Tech Indie,” leading naturally to “Tindie.”

What is Sold Here?

Need a 6-way MIDI hub? You’ll find it on Tindie.

“Low run electronics” is the obvious answer, but there is much more available here. Some items aren’t really electronic at all. Perhaps you could say that the primary things sold here are items that would appeal to the segment of the population that really geeks out on electronics, photography, 3D-printing, and other technological pursuits. Also, musical devices like MIDI controllers or synthesizers are quite popular, and unique LED light sculptures and jewelry seem to be popping up recently.

To put it another way, things like knitted sweaters or paintings might not fit in here. On the other hand, a robot or innovative tool to help with either pursuit would certainly be a welcome addition! Tindie is the place you go to find bleeding edge electronics without having to wait for those products to make it all the way through the cycle. It’s like getting an inside line on knowledgable-consumer-ready prototypes of the hottest stuff.

Who is Selling?

Like Etsy, Tindie aims to make it easy to go to market with a product before you’re to prove a huge market for the device. According to my interview with Iqaudio founder Gordon Garrity, they had no idea how to sell things on the internet, but “Tindie makes it easy, real easy.” Now that they have a better feel for things, and have tested their market, they have their own independent online presence. Whether you want to stay small, or have bigger plans and just want to get started, there’s a place for you on Tindie.

What’s the Story with the dog?

The dog’s name is “Ohm.” There is also a flea featured here as sort of the mascot of Tindie’s “Flea Market”. Although I haven’t been told officially, I’d have to assume that they are not friends.

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This LORA/GPS board designed by Dragino Tech is made for the Raspberry Pi and opens up a host of cool projects for that most popular of Single Board Computers. LORA (which stands for Long Range Radio) is a unique type of modulation that is best described as a frequency modulated FM chirp. Other types of modulation you may have heard of are PSK(Phase Shift Keying) and FSK( Frequency Shift Keying). LORA has advantages over those modulation schemes in that it increases the possible range and the receiver sensitivity.

The creators of LORA are a company called Semtech and they pitch it as the as a solution for IoT and M2M( Machine to Machine) networks. Currently GSM is used widely in M2M applications. IoT devices  communicate with standards like Bluetooth or WiFi. GSM has the advantage of high speed data transfer and long range but the power used to send and receive is too large to use with batteries for any decent length of time. Standards like Bluetooth and WiFi are lower in power usage, have good data transfer rates,  but are limited by range. LORA combines low power usage with the long range of several kilometers, at the cost of speed.

The highest possible speed with LORA is around 38 kbps. To put this speed in context, it would take 11 minutes to transfer a 3MB file (average mp3 file roughly). Speed isn’t what LORA is designed for and the benefits from having low power use and long range are huge. In applications with remote sensors( e.g. environment sensors, water level sensors, movement sensors), they only need to transmit a few bytes quite infrequently e.g. a sensor reading a few times per hour. LORA really shines here and could theoretically transmit for years on a single battery charge.

The chip that the LORA/GPS board uses for communication is the SX1276/SX1278 transceiver IC made by Semtech. The combinations of GPS with LORA open up the possibility of some really interesting projects like long range remote monitoring and tracking for example. You have long range, it can last for years on a single charge, and you know your exact location. What would you make?

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OSHCHIP combines an ARM cortex M0 processor and a Bluetooth Low Energy radio on a tiny PCB that is breadboard compatible. This board is great for those looking to get a start in ARM development especially since it comes with great documentation showing you how to hook everything up and some example code that you can compile yourself using the mbed online compiler.

The ARM processor and radio are combined into a single Nordic Semi nRF51822. The ARM processor runs at 16MHz and has 256Kb of Flash and 32Kb of SRAM. The radio included is a multi-protocol 2.4GHz compatible device. It works with the famous NRF24L series chips as well as supporting Bluetooth Low Energy (AKA Bluetooth Smart).

The OSHCHIP comes with 3 on board LEDs, a 10 bit ADC, and 14 GPIO pins to play with. The chip is programmed using the SWD (Serial Wire Debug) protocol. There is a SWD programmer available from OSHCHIP that is compatible with the Keil IDE and gives you some nice debugging options like breakpoints, examining memory, stepping through code etc.

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If you’re a fan of Star Wars, and happen to check out Ken.Do’s store, the first thing that will likely grab your attention is the “Deathstar-like Yo-yo”. Ken.Do recounts: “My son wanted a yo-yo. I made him a yo-yo.” Now you can have this 3D-printed yo-yo as well for $12 plus shipping. It’s really a clever design, and I’m honestly surprised we haven’t seen something like this mass-produced.

The rest of this store features some really cool stuff as well, including a hexapod robotic platform, as well as several quadcopter designs. The most unique of these is his Flying Ship robotics platform seen in the video below.

This robotics platform can float as well, with a sectioned hull that should survive some damage without sinking. The ship’s designer built this because he lives on a Pacific island surrounded by water, and has been experimenting with sonar mapping. Naturally something like this makes a great platform for these types of endeavors.

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This low cost programmable capacitor is something everyone should have in their parts box as it’s basically guaranteed you’ll have a use for it at some point. In a pinch, you can get by with using trimmer capacitors but these have the disadvantage that you don’t know the exact capacitance it’s set to. Just that it is somewhere in the given range.  Another disadvantage is that to be really flexible and have a big range of capacitance you would have to stock out your parts bin with a large number of trimmer pots.

This 5 decade variable capacitor gives you the huge range of 100 pF to 9.999uF to work with. You can fine tune it to within 100 pF which will be more than enough for most hobbyist use. The capacitors used have a tolerance of 5% on their capacitance. The uses of programmable capacitors are too numerous to possibly list. From working with op-amps to tuning a filter,  having one of these capacitors at hand will make your life easier and let you work faster.

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If you’re considering selling your devices online, there are many options out there, but if you want to test the market with knowledgeable customers who love cutting-edge hardware, and with the potential to grow beyond a niche electronics site, Tindie is the way to go. Gordon Garrity, after starting on Tindie, has now grown to the point where he has his own e-commerce site focused on Raspberry Pi audio accessories!

As another iteration in my seller interview series, check out what he has to say about his experience selling on Tindie:

How did you get started?

Over a few beers at home. I came up with an idea to deliver great audio quality to people using the Raspberry Pi, I met with Eben Upton (of the Pi Foundation) at a music hack event and it grew from there.

What is the best thing about selling on Tindie?

We had no clue on how to sell on the internet, nor how to set up a web presence. Neither did we have the funds to throw at a couple consultants to do it for us. Tindie makes it easy, real easy. It gave us an immediate e-commerce solution and allowed us to point potential customers at it. Tindie got us going and it gave us a presence in the right marketplace. Knowing that there was someone there, in the background, to help IF things failed was useful – even though we really didn’t have anything to panic about.

What is the worst?

I guess it was that both Tindie and us were growing and learning at the same time. We had a few hiccups but anything that was ever an issue was pretty quickly resolved. I missed having a telephone number [support is done through email] to contact someone on rather than just email though.

Have enough stock and communicate: You’ll not know the possible sales but at least tell people when you’ll have more. Work fast: Ship quickly

Anything you’d like to add?

If you don’t try it you’ll never know what’s possible. We’ve all but stopped selling on Tindie now as we’ve created our own e-commerce site [linked above]. As a stepping stone to greatness – Tindie helped enormously – thank you.

I suppose the takeaway from this is that if you have a great electronics idea, but don’t know how to sell it on the Internet, Tindie is here to help. Also, don’t panic.

We wish Gordon continued success in the future!

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The Berry IMU (Inertial Measurement Unit) allows you to measure orientation, velocity and magnetic fields. With this information you can work out which way is up, how fast you’re going, and which way is North. Just think of the possibilities. Add in a Raspberry Pi and you’ve got enough projects to keep you busy till the end of time.

The BerryIMU is a breakout board for the LSM9DS0, a motion sensing IC made by STMicroelectronics. It contains an accelerometer, a gyroscope, and a magnetometer to give you a grand total of 9DOF (Degrees Of Freedom). Whilst the breakout is designed to easily connect to a Raspi, it can also be easily hooked up to a microcontroller because it communicates over SPI or I2C.

IMUs are used in a whole range of applications because it turns out it’s really handy knowing your orientation and how fast you’re going. Some examples are balancing robots, quadcopters, and gesture sensing — there’s even one in your phone so you can play Pokemon Go.

Check out the video below of the BerryIMU hooked up to a Raspberry Pi:

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Murphy’s Law waiting to happen

Things can get very messy very quickly when trying to set up a wireless sensor network. Let’s say for example you are using the NRF24L01+ and want to have several nodes positioned around your house. Each node needs a microcontroller on it and a power source of some kind.

You can put together a circuit on a breadboard or some strip-board. But knock just one of those jumper wires loose or bridge a connection during soldering and you’ll spend ages when chasing down the problem. Having a dedicated board makes the process much less painful and reduces the number of things that can go wrong.

With electronics people start off learning Ohms law and so on, but the law they don’t teach is Murphy’s law. What can go wrong will go wrong.

Sure, you can spin your own board, but if your main goal is getting a stable sensor network up and running you start looking around for shortcuts. This offering takes care of microcontroller, regulated power, and two wireless module footprints in one small outline. The board supports the NRF24 wireless transceiver and a Bluetooth module.

The voltage regulator used is the MCP1703 made by Microchip. This regulator has a crazy low quiescent current draw of only 2uA meaning this board is suitable for use with battery powered applications that need to last a long time. With this board, all you have to do is plug in your NRF / Bluetooth transceiver, hook up a power source, program the microcontroller, and you are good to go. The ATmega328P has tons of Arduino Libraries available for it so you can get your project up and running quickly and easily.

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