Tindie

Since Espressif released the ESP32-Cx series of RISC-V-based microcontrollers, they’ve been steadily increasing in popularity and lifting the banner of RISC-V along with them. The ESP32-Sx series isn’t going anywhere, but if you’ve wanted to hack on the new open architecture, the OKD Bee and the OKD Nova are affordable and easy to use!

Both boards have great quick-start pages (like this one for the OKD Nova) that show you how to get started using the Arduino IDE. The quick start guides also include excellent high-resolution images with the board pinouts, as well as information about the chip configuration, number of GPIO, etc. The RISC-V processor is part of an open architecture, so you can also quickly get started using open-source toolchains like MDK or Espressif’s own ESP-IDF. The ESP32-C3 also supports using PlatformIO, which integrates into VSCode and enables a full GUI debugging environment.

Note that both boards require external antennas; any 2.4GHz U.FL antenna will do. The nice thing about having an external antenna connector is flexibility in antenna choice; you can buy a bigger, high-gain antenna to get more range or get a tiny adhesive-backed flexible antenna to use inside a small enclosure. You can even find some enclosures on Tindie that have integrated U.FL to SMA connectors!

If you’ve ever wanted to play around with RISC-V and simultaneously tap into one of the most cost-effective wireless microcontroller platforms around, these boards are an excellent choice!

Keep Reading ›

A while back, we covered the LogicShield by METE HOCA; well, they’ve now stepped it up a notch by reducing the price and increasing the usability and educational application with the new LogicBoard. Eliminating the requirement for an Arduino Uno brings the cost per board to a level where an educator could afford to buy 10 or 20 boards without completely emptying what small budget they may have.

Other improvements include switches to make changing the inputs easy; using 0.1″ headers for connections, allowing inexpensive jumpers to be used to connect the gates together; the ability to link multiple gates together in sequence to create more complex logic equations; and having fixed 0 and 1 input headers available. Altogether, this makes the LogicBoard a great choice for STEM educators who teach logic gates as part of their curriculum.

As an educator, I also appreciate that the name of the company has been moved from the front of the board to the back, giving a cleaner, more professional look. The listing also says that female-female jumpers are included, which is an excellent touch that makes educators’ jobs easier (being able to buy everything needed as a single product is great). The only thing missing is the option to include an appropriate power supply — but because it accepts a wide input range (4-14V DC), presumably most STEM educators have a few spare power supplies around. It was designed to be able to take the same power supply that powers an Arduino Uno, which is again a nice touch as being able to reuse components in a lab makes things easier for the instructors.

If you are in the STEM education field, check out one of these boards and simultaneously support a fellow maker while getting a tool to help educate the next generation of hackers and makers!

Keep Reading ›

When outfitting your electronics workbench, one of the most essential tools is a variable DC power supply. In fact, I’d argue it’s firmly in the top 5. Such power supplies typically feature a positive voltage output as well as ground, but what if you actually need positive and negative potential outputs instead? Rather than rigging something up yourself, you can now get this capability in the form of the Power Supply Rail Splitter from Repowered Electronics.

The device turns a standard power supply output into a +1/2 Vin and -1/2 Vin leg, plus a 0V ground. So if you need ±5V, you simply plug your supply output into the splitter input and set the supply to 10V. Banana jacks are provided for secure connections all around, and there’s an earth ground on the input side that is used for filtering.

One interesting feature of the device is that it can actually maintain the proper voltages even with a current imbalance. So if you’re pushing more current into your circuit via the Vin than is coming out via Vout, it keeps the voltages steady–up to a 100mA of imbalance at 30V. Of course, per Kirchhoff’s law, current in at a junction must equal current out. However, you may encounter situations where other circuitry provides an alternate current path, creating such an imbalance without violating the laws of physics.

Keep Reading ›

The Tindie community never ceases to amaze me with their dedication to restoring and resurrecting retro computers and hardware. Of course, the Apple II has a strong fanbase and many dedicated users, even to this day. So it’s no wonder that new hardware is still being developed! The ∀2 Analog board is an amazing add-on for your Apple II. Not only does it make using an Apple II with modern monitors easier with a standard VGA connector, but it also supports many of the different video modes used by the Apple IIe like High-Resolution Graphics mode (HGR), Double High-Resolution Graphics (DHGR), plus 80 column modes and more.

This project builds on another board, called the AppleII-VGA, but uses a few tricks to shrink the logic down to a single chip, while also introducing the power of the RP2040 for future expansion. The board comes with a floppy disk (how many products still come with floppy disks?!) loaded with utilities for the card, plus a way to transfer files to and from the Apple II!

If you’re an Apple collector and you want to give some new life to your Apple II, check out the ∀2 Analog by ∀2 Retro Computing!

Keep Reading ›

I kind of fell into electronics later than many and that’s led me to mainly be a digital type. Show me some 4000-series CMOS chips and I’m on reasonably familiar ground. It often embarrasses me how little I know of the dark art of the Op-Amp! Despite this, even I have heard of the classic 741 op-amp originally designed by Fairfield Semiconductors. If you’re interested in knowing what’s going on under the hood of this classic chip the OA741D Op-Amp Bare PCB kit is what you need!

This PCB allows you to build a through-hole discrete component version of the 741, and the components needed are commonly available. It’s built around 2N3904 and 2N3906 complementary NPN/PNP transistors with the rest of the components being pretty standard; capacitors, resistors and a couple of diodes. Once built you have a fully functional 741 with nice header pins for you to test or wire into your circuits.

Being able to probe the normally inaccessible internals of the 741 is also a great way to learn about what goes on inside an op-amp, and how each section of the circuit works. You can learn about differential inputs, current mirrors, and transistor biasing! Ken Shirriff has an amazing blog post about the 741 and if you read through that while playing around with this discrete version, you’re sure to learn more about integrated circuits than you thought possible!

Mostly DIY RF has not only done a great job on the PCB, but they have shared the source on their GitHub page; this includes a nicely annotated PDF schematic that acts as a build guide. Whilst you could buy some modern silicon 741’s for your next op-amp project there’s nothing, other than size, stopping you from using this excellent PCB in a project or on your lab bench!

Keep Reading ›

This high-voltage optoisolated interface board was initially designed for use with 24VAC solenoid valves used in irrigation, but can be applied to any circuit where a microcontroller needs to detect a high-voltage signal. By current-limiting, voltage dividing, Zener clamping and then optically isolating the input, a huge range of voltages can safely be detected by 3.3 or 5V microcontrollers. There is also a second Low-Voltage input that bypasses some of the protection circuitry.

Adjusting resistors R1 and R2 is needed to accommodate higher or lower voltages. The Zener diode D2 clamps any surges or spikes, and R4 limits the current flowing into the LED side of the optocoupler so as not to fry it. By tweaking R6, you can change the overall sensitivity of the optocoupler and require more or less current flowing through the internal LED to trigger the output.

Any time you are working with voltages above the Vcc of your microcontroller, it’s handy to have modules like these to simplify development and ensure you don’t fry your control electronics. I’m sure I’m not the only one who has accidentally connected the black wire to the yellow wire and then suddenly all the magic smoke escapes from your Arduino! So protect your project, and check out Concise Technology’s products!

Keep Reading ›

We love the retro computer community on Tindie, and they, time and time again, impress us with their dedication to all our computer heritage. This product is no exception, a complete replacement motherboard replica for a late issue Spectrum 48K.

This issue 6A board was fitted to both Spectrum 48k and Spectrum + and was the last board iteration for these platforms. It differs somewhat from earlier Spectrum boards so double-check your machine if you are thinking of buying one as a replacement. As many Spectrum with the original of this board fitted will be knocking on 40 years old, we suspect there may be a few worse-for-wear machines out there in cupboards! Like any older PCB, the originals can be prone to wear and oxidisation as well as potentially accumulating numerous track and pad repairs that start to fail. Well, with this replica board, you could swap all your glorious Spectrum components onto a brand-new shiny PCB.

Of course, the other option is you could build a replica based on this board. In the product documentation, there is a BOM for all parts needed including viable alternatives for those difficult to source components. The PCB is available in a more classic green if the exciting purple option is too rich for your tastes!

Finally kudos to Devzine.pl for creating this and also taking great photographs for the product page, even if you don’t want to resurrect a Spectrum, the pictures are well worth a look!

Keep Reading ›

The Raspberry Pi Pico is so prevalent in the electronics hacker scene that it seems just about everyone has a couple on their desk or in a drawer. There are many different options for programming them: you can use MicroPython, C/C++, CircuitPython, and of course the Arduino environment. But if you want to program your Pico at the lowest level (programming a bootloader, or using the Pico SDK with C/C++) then you need to connect to the SWD port on the RP2040. There are two nifty programming/debug probes developed by 8086 Consultancy: the PiProbe and the PicoProbe Sled.

The PiProbe attaches to any Raspberry Pi and gives you UART, SWD and power outputs to make powering and programming any Pico/RP2040 product a breeze. Using OpenOCD you can both program and debug the Pico. GDB is used to debug, allowing you to single step, examine memory, set breakpoints, and pretty much have full control over the chip, which can be priceless when troubleshooting issues.

If you instead want to use your Pico as a programmer/debugger for another target Pico, then you can use the PicoProbe Sled. This breaks out the UART and SWD to similar JST connectors and also breaks out additional connections (including power) on the 0.1″ header. Both of these boards have the option to include compatible JST 3-wire cables in various lengths (10, 15 and 20cm), which you can use if the target board has a compatible connector.

Note: an earlier version of this post mistakenly assumed that the PiProbe and the PicoProbe Sled could be used in a debug->target setup; however, both boards are debug probes and you cannot program the Pico connected to the Sled from the SWD header.

8086 Consultancy has a range of other super cool products, including lots of adapters and boards to help you hack on USB as well as many other neat add-ons for Raspberry Pi products. Check them out if you want to learn more!

Keep Reading ›

I’m a bit of a nerd (apparently it’s a job requirement here), so I sometimes dive deeply into a topic. Not that long ago, I took a very nerdy dive into USB-C and USB-PD (Power Delivery) by reading the specification document provided by the USB Implementers Forum. It was great to read right before going to sleep! Since then I’ve been looking for various devices for hacking on USB-PD and seeing how different devices respond. So when I saw the Altmode Friend I was immediately intrigued!

Essentially, this board intercepts all the important USB-C signals, and taps into them using an RP2040 and a FUSB302B USB-PD front end. This gives you the ability to simply sniff the bus to see if a device is compliant with the specification, actively modify what is being sent back and forth, or even add USB-PD to something that doesn’t support it at all. The RP2040 can be connected to either USB-C port; it’s configurable just by moving two jumpers. There are even open-source USB-PD stacks available, so you can get started very quickly!

The Altmode Friend shown configuring a USB-PD charger to output 12V

For those who haven’t read the USB-PD spec, it’s a relatively new protocol that allows USB devices to communicate with chargers and other power supplies. They can negotiate higher voltages and current limits, allowing faster charging or the ability to power more devices. My smartphone communicates with my wall charger; it starts at 5V with a 100mA current limit for a very brief time. Then it communicates and asks for a list of power profiles supported by the charger; it then selects the 9V @ 3A profile and starts charging at 18W! My Nintendo Switch talks to the exact same charger, but instead asks for 15V @ 2A, charging at about 20W. It’s a really neat way to have the same charger adapt to different devices, while still being able to fall back on 5V for devices which don’t support USB-PD.

The Altmode Friend can help you tap into the power of USB-PD; so if you’re interested in hacking on USB, pick one up and check out the specification, and see what you can come up with!

Keep Reading ›

A pet peeve of mine has always been the lack of camera peripherals for microcontrollers. I look at the listing and cry out to the skies, “why, oh why, do we all think microprocessors are the minimum requirement for any photo capturing?!”

Okay, maybe I’m not that dramatic, but when I see a listing for a microcontroller-based camera, I do get very excited. So when the T-Camera S3 was posted on Tindie, it was just as quickly added to my cart.

This wonderful little module is built with an ESP32 board at its heart, meaning right out of the gate, you have WiFi and Bluetooth connectivity! The included camera has a resolution of 1600 x 1200 pixels, an Ultra-Extended Graphics Array (UXGA) resolution. There is also a Passive Infrared sensor and microphone on board, giving you lots of fun peripherals to play with. And something this kit offers that I haven’t seen in others is the inclusion of a 128 x 64-pixel OLED screen, giving you a way to confirm captured data and wireless transmission.

This kit is offered by Lilygo, the China-based open-source store. If you’re looking to pick one up soon, I’d hurry, because the store is going on a break starting January 14th. The Tindie listing for the T-camera lets you choose between just the populated board and accessories, or adding the case as well.

Keep Reading ›