Tindie

When I saw this listing, I couldn’t help but think “What a cool idea!”. An inverting audio amplifier with potentiometer adjustment in a DIP-8 ready-to-breadboard package! This would be so handy when prototyping any audio-related projects. No matter what, you seem to always need some gain along the way, and being able to just plug in a ready-made solution will save breadboard space and prototyping time.

By placing all the components in the same footprint as a DIP-8 op-amp, you get all the functionality without having to calculate and add all the external components necessary. Delivering anywhere from +/-20dB of gain (yes, it can attenuate as well as amplify!), this inverting op-amp is perfect when used as a final amplifying stage, as a pre-amp driving some other circuitry, or even just as inter-stage gain steps between successive effects.

It does require a bipolar supply. A simple way to get a very clean, stable bipolar supply is to use two 9V batteries, with the negative terminal of one connected to the positive terminal of the other. This works as your “ground” or reference voltage, and then you are left with exceptionally noise-free +/-9V supplies for op-amps and other circuitry (thanks to Ben Krasnow for this tip!).

The documentation is very clear and well-designed, with easy-to-read schematics and pinouts. The included op-amp isn’t specified but it’s likely something along the lines of a TL081 or a similar high-quality audio op-amp. Having building-block parts like this in your drawer can make prototyping and testing so much simpler, and knowing that it just works can reduce headaches when something does go wrong!

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The Raspberry Pi has so many uses it’s getting ridiculous. Add another one to that list — OpenOCD supports JTAG programming and debugging using Pi GPIO! While you can wire things up manually, having this nicely laid out JTAG hat makes things easier. You can directly plug in a 6-pin header, or connect jumpers directly to the labelled pins. You can also change the voltage level to 3.3V or 5V easily. The board uses voltage buffer transistors to safely interface with devices that have I/O voltages from 1.65V up to 5.5V.

JTAG is a great way to program and debug FPGAs, CPLDs, and many microcontroller families including all ARM Cortex devices. OpenOCD, xc3sprog and UrJTAG are all supported. Once connected, typically you use something like arm-none-eabi-gdb to interface to the target processor. GDB allows extremely fine control over the processor. You can easily examine any part of memory, program the flash, change registers, single-step the processor, use breakpoints and watch variables, and much more. GDB is a fantastic tool, but it does take a bit of practice to use effectively. Many IDEs have built-in support for GDB and can make using it a bit easier.

The mounting hardware isn’t included, but because this board uses the standard HAT layout, all you need are a few M2.5 screws and 11mm spacers. The HAT is compatible with all 40-pin Raspberry Pi devices, but technically I think it would also work on the older 26-pin devices without any issues (though the 40-pin header might get in the way). I still use and treasure my original Model B so I like to see if modern boards still work with the old hardware!

If you’re into embedded development, grab one of these boards as a backup to or instead of your typical JTAG probes like the Segger J-LINK. Use what you already have for a whole new purpose! Now that’s the hacker mindset.

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As part of tuning engines, the vacuum system needs to be calibrated to ensure that the correct amount of air or air/fuel mix is being drawn into the engine. On multi-carb/multi-throttle systems, this is even more critical because the amount of air or air/fuel needs to be carefully balanced between all cylinders. This handy-dandy portable digital vacuum gauge has been designed for this task in particular.

In the past, manual vacuum meters could be used, but most mechanics only have one, and so you’d have to test one cylinder, and then the next, etc. However, with a multi-channel system like this, any multiple of 4 cylinders can easily be measured simultaneously, making it easier to spot issues and fine-tune the amount of vacuum. Mismatches between cylinders can reduce performance and decrease fuel economy, as well as increase the amount of partially burnt fuel exhausted from the engine — a significant contributor to vehicle emissions!

With a 12-bit ADC and self-calibration features, this tool will be accurate and useful for many years. It has a built-in 1200mAh battery that can be replaced by the end-user, further extending its life. Handy features such as the bars changing colours when readings are within 1-2% of each other mean it’s easy to use, and the device will self-compensate for ambient temperatures from -40C all the way to 125C (though I hope it never gets that hot in your shop)! It even comes with various silicon hoses to attach to most common vacuum ports. If you’re ready to ditch your old analogue meter (and maybe pick up a cool lamp) go check out origin_v0id’s store page!

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Electromyography (EMG) is the measurement of skeletal muscle electrical activity through sensors placed on the skin. EMG can be used to measure both voluntary and involuntary movement. Because the electrical potentials are so small, you need a fairly high-gain preamp connected to the sensor to get useful measurements. This compact Muscle BioAmp BisCute sensor board is just the ticket for amateur EMG measurements!

It uses the tried and true LM324 quad op-amp to amplify the raw signal, as well as a 72-720Hz band-pass filter to get rid of signals outside the area of interest. This makes it much easier to interpret and display the gathered data. The kit is DIY, but it’s all through-hole soldering and there aren’t many parts, so even fairly new solderers shouldn’t have too much trouble assembling it.

The kit includes a 3-sensor lead as well as a band to help hold them in place. Alternatively, you can also buy disposable medical-grade adhesive-backed EMG sensors (the same type you’ll see used in hospitals) if you are going to be using the sensors on more than one person. They are quite inexpensive and it’s worth grabbing a bunch in bulk if you’re going to be doing a lot of experiments.

The output from this board can go directly into the ADC of any microcontroller, or even directly into an oscilloscope. Always make sure that your measurement devices are isolated from the mains supply using an isolation transformer, or run your devices from batteries — never attach devices like this to instruments that are plugged into the wall! Even your laptop should be unplugged if you are programming a microcontroller that’s connected to this board. Be aware of your environment and always think about safety when starting your journey into bio-hacking!

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Everyone has seen those cheap LED testers found all over the web at low prices. But how accurate are they? They’re not capable of testing RGB LEDs either, and certainly can’t measure the forward voltage drop. Well, check out this Multifunction LED Tester kit from Tindie seller LEDsales. It is very well-designed and absolutely packed with features!

It can test LEDs at a range of currents from 1 up to 40mA, using metal film resistors for good long-term stability. It also can test both common anode and common cathode RGB LEDs, selectable with a flick of a switch. As an added bonus, it can even test Superflux LEDs (the 4-pin LEDs often known as Piranhas).

The voltmeter on the front will show the battery voltage when no LEDs are connected, but when testing an LED it will show the forward voltage drop (Vf) of the LED! This is a very useful feature and can help you pick out slightly damaged or mis-matched LEDs. The illuminated button in the centre of the panel is used for brief testing, or you can choose to flip one of the three switches to constantly power one of the test banks.

This is not a precision tester, but as you can see in the included chart the measured values are within a fairly good tolerance. Only the red LEDs tend to be a bit on the high side. But for day to day measurements and binning LEDs, it’s an excellent tool! The included documentation is extremely well-written and easy to read, and it’s all through-hole soldering with large pads so even a beginner should be able to assemble the kit. If you work with LEDs often, pick one up and check your LEDs!

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If you need to control LEDs remotely, say for an art installation, you have a few choices on how to do it. You can have a microcontroller near each group of LEDs, playing back a pre-programmed pattern. You can even go to extremes and have a single, tiny microcontroller controlling each LED! But the way professionals do it is with RS485 or RS422. This differential Neopixel transceiver and OctoWS2811 dual transmitter pair by Tindie seller oksquared is a great example of using existing, robust technologies to create a simple solution to the problem.

Note that both products can be used as the transmitter side, but only the transceiver can be on the receiving end. The transceiver uses the SP3485CN differential chip, and the octo-transmitter uses a pair of SN75174 differential line drivers. The OctoWS2811 board can send up to 8 Neopixel data streams at once, and so must be split into multiple cables if using all channels. This way, a single powerful microcontroller or SoC can remotely control huge numbers of LEDs. Putting the power supplies near the LEDs and having just a single cable coming in with data makes installation and testing much faster and easier. Plus, differential buses are much more resilient when it comes to EMI and other sources of noise, meaning long cable runs near other electrically noisy devices are a feasible solution. As a bonus, this transceiver also uses CAT5 Ethernet cable, which is already rated for installation inside walls and so is a very good, safe choice for the job!

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If you’ve ever wanted to get into LoRa/LoRaWAN, this is an excellent little board to get started with! Powered by an STM32L082, the Grasshopper LoRaWAN Development Board is a tried and tested development platform. The module also contains the SX1276 LoRa radio transceiver, and with the chip antenna can be used in many countries around the world; most of Asia, Australia, Europe, India, Korea and North America, as the transceiver can be tuned between 868 and 915MHz.

LoRa (short for Long Range) radio is a proprietary, spread-spectrum, long-distance radio protocol focused on low power consumption and reliable transmission. It’s pretty incredible once you actually try it — the distances it can cover are incredible, even in dense, electrically noisy urban environments! LoRa is perfect for battery-operated devices that might be put into difficult to access areas (up a tree, on the side of a cliff, etc.) where it can gather data and wirelessly transmit it to a base station hundreds of meters away.

With this board, an 18650 battery, and a solar panel, you could create a long-term data collection device for use in just about any environment. Popular choices are of course weather and air quality monitoring; but radiation monitoring, wildlife study and tracking, and asset tracking are all popular applications as well.

Dive into the world of LoRa with this super easy to use, Arduino-compatible board!

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The bootloader is what distinguishes an Arduino from an ATmega328P development board. It’s the crucial piece that allows software to be easily flashed via the serial port, and if the chip gets blanked or somehow corrupted, you need to re-flash the bootloader. This handy, portable bootloader flasher from DSTIKE is the perfect tool for a quick bootloader burn!

It’s happened to me for various reasons — usually because I use my Arduino boards in combination with an AVRISP and Atmel Studio instead of the Arduino environment — but when you want to use it with Arduino again, you have to flash the bootloader. Now, this isn’t too much of a hassle if you have an AVRISP or other AVR programmer handy, but being able to just quickly clip onto the programming pins and push a button is just faster, a bit more foolproof, and great if you’re somewhere without a laptop. Stick one in your toolbag and you’ll always be able to “factory reset” any ATmega328p-based Arduino!

Another recent product is this ZIF socket programming board for the ATmega328P. The zero-insertion-force (ZIF) socket makes inserting chips painless, with no risk of bent or broken pins. It also has a reset button, and a standard 6-pin AVR programming header. There’s only a couple of these in stock, so grab one and pair it with the DSTIKE bootloader burner for a super-easy, portable offline ZIF Arduino bootloader burner! (Phew, try saying that three times fast!)

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Indoor air quality has been studied for decades. It’s been widely shown that air inside buildings is quite different from outdoor air, primarily because of the concentrations of CO2. High levels of CO2 can cause sleepiness, inattentiveness, difficulty solving problems, and in high enough levels can cause unconsciousness. This handy, portable indoor air quality measurement unit gives you an instant snapshot of CO2 levels, temperature, relative humidity, and air pressure.

Since the start of the pandemic, indoor air quality and circulation have been key in tracking and reducing indoor transmission of the virus. While it’s not easy to measure quantities of air for the virus itself, we can do the next best thing and simply measure how much of the air has been breathed by humans. Humans inhale oxygen, nitrogen, etc. and the alveoli in your lungs exchange that oxygen for CO2 in your bloodstream.

So, if we can measure the amount of CO2 in the air, we can get a general feel for how “stuffy” or “used” the air in a room is, which, assuming you have someone who is sick, can also tell you how much virus is likely to be in the air. This can prompt air recirculation systems like HVAC to turn on, or even just get someone to open windows. This can very rapidly reduce the level of CO2 in an area, and make people feel more alert and refreshed, as well as helping reduce levels of transmission. It has also been shown that CO2 levels can affect mood, so fresh air will also keep people happier!

This project uses the SCD40 CO2 sensor from Sensiron, offering +/-(50ppm + 5%) accuracy in measurements. Unfortunately, these sensors are expensive to manufacture, and so a large portion of the cost of this unit goes towards the CO2 sensor alone. However, the benefits of knowing the air quality at your home or office can be huge, so this is a great investment to make. Plus, the unit includes a USB to serial chip, so you can hack on the device and integrate it into your HVAC or other air quality systems!

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As soon as I saw this product listing, I had to immediately go look up more information about this chip. This CH347 Development Board has, as the name suggests, the CH347 chip as well as a USB-C interface and a DIP switch. The features blew me away when I first read them: USB to UART, I2C, SPI, JTAG or just GPIO! We’ve all got drawers full of USB to serial UART boards for programming Arduinos and other devices that use serial, but this chip takes things a step further and adds a bunch of other serial protocols. It’s like the Swiss Army knife of USB chips!

It brings to mind the venerable Bus Pirate, an amazing board by Dangerous Prototypes which allows you to connect to just about any serial protocol out there, as well as a host of other features. While this chip has some of those same features, the interface is quite different. This chip is still so new that it has barely started appearing in Western markets yet, so this is your chance to be ahead of the curve! That of course also means there is very little software yet available for interfacing with this chip.

The company that makes the CH347, called WCH, does have some documentation on their website, but it hasn’t yet been translated into English. There is a datasheet download for those who can read Mandarin, but I suspect most of the experimentation will be looking at the demonstration code provided here. The chip can run in a few different modes, including HID (Human Interface Device) meaning it can act like a keyboard or mouse and send data that way. It also supports CDC which allows it to send data in a variety of ways, including appearing as a COM port. The demonstration code is very Windows-centric, but once the protocol is figured out, I suspect it won’t be long at all until we see software for this chip on all platforms. Once that happens, expect to see this chip all over the place!

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