"The Great Resistor" color code illumination project

The Great Resistor Embiggens The Smallest Value

November 5, 2022 by Dave Walker 29 Comments

With surface-mount components quickly becoming the norm, even for homebrew hardware, the resistor color-code can sometimes feel a bit old-hat. However, anybody who has ever tried to identify a random through-hole resistor from a pile of assorted values will know that it’s still a handy skill to have up your sleeve. With this in mind, [j] decided to super-size the color-code with “The Great Resistor”.

Resistor color code from Wikipedia with white background — How the resistor color-code bands work

At the heart of the project is an Arduino Nano clone and a potential divider that measures the resistance of the test resistor against a known fixed value. Using the 16-bit ADC, the range of measurable values is theoretically 0 Ω to 15 MΩ, but there are some remaining issues with electrical noise that currently limit the practical range to between 100 Ω and 2 MΩ.

[j] is measuring the supply voltage to help counteract the noise, but intends to move to an oversampling/averaging method to improve the results in the next iteration.

The measured value is shown on the OLED display at the front, and in resistor color-code on an enormous symbolic resistor lit by WS2812 RGB LEDs behind.

Inside view of the great resistor showing WS2812 LEDs and baffle plates — Inside The Great Resistor, the LEDs and baffle plates make the magic work

Precision aside, the project looks very impressive and we like the way the giant resistor has been constructed. It would look great at a science show or a demonstration. We’re sure that the noise issues can be ironed out, and we’d encourage any readers with experience in this area to offer [j] some tips in the comments below. There’s a video after the break of The Great Resistor being put through its paces!

If you want to know more about the history of the resistor color code bands, then we have you covered. Alternatively, how about reading the color code directly with computer vision?

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3D Printed Newtonian Telescope Has Stunning Looks, Hadley Breaks The Bank

November 4, 2022 by Ryan Flowers 49 Comments

Have you ever considered building your own telescope? Such a project can be daunting, especially if you grind your own mirrors. But with a 3D printer, hardware store bits and bobs, and some inexpensive pre-made mirrors, you too can be the proud owner of your very own own Hadley — a 114/900mm Newtonian Telescope that can cost less than $150 USD to build! Check out the video below the break to get a good scope on the project.

Astrophotography is possible with the Hadley

The creator’s stated goal is to “make an attractive alternative to the shoddy, hard to use “hobby-killer” scopes in the $100-200 range“, and we have to say that it appears to have met its goal admirably. The optics — the most complex part of any build — can be easily purchased online, and the rest of the parts are available at your local hardware store.

While the original build was provided in Imperial measures, a metric version is now available. Various contributors have created a rich ecosystem of accessories and alternative versions of various parts, all in the interest of making the telescope more useful. Things like tripod mounts, phone mounts (for use with your favorite star chart app) and more are only a click away. The only real question to answer is “What color filament will I use?”

Of course, sometimes light waves can get a bit long in the tooth, and for those cases you’ll want a radio telescope, which can also be DIY’d thanks to the availability of satellite dishes and SDR dongles!

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Heirloom Knife Will Carve Pumpkins For Years To Come

November 3, 2022 by Kristina Panos 6 Comments

Halloween may be behind us, but that just means that we’ve reached the best time to buy pumpkins. After all, it’s still fall, and there are pies to be made and tables to be decorated. Why should carved-up pumpkins be restricted to spooky season?

The only problem is that it’s 2022, and we’re still expected to use those terrible little serrated knives to carve our pumpkins. Those orange-handled garbage ‘knives’ are hardly suited to cut the lid, much less carve any of the intricate designs that come in the little booklet. So what’s a pumpkin-carving enthusiast to do? If you’re [XYZ Create], you make your own out of walnut, maple, and a gently-used jigsaw blade that’s still way sharp enough to tear through pumpkin flesh.

[XYZ Create] started with a nice chunk of walnut, which he split lengthwise in order to insert the blade, which sits in a cavity within a thin piece of maple. Once [XYZ Create] had the handle ready to go, he inserted the jigsaw blade and epoxied the sandwich together. After sanding down the edges to make a comfortable grip, he finished off the build by rubbing a bit of carving board wax into the handle. Check out the build video after the break.

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A Pi Pico plugged into a breadboard, with an I2C OLED display connected to it

Need An USB-I2C Adapter? Use Your Pico!

October 31, 2022 by Arya Voronova 12 Comments

Given its abundance and simplicity, the RP2040 has no doubt become a favourite for USB peripheral building – in particular, USB-connected tools for electronics experiments. Today, we see one more addition to our Pico-based tool arsenal – a USB-I2C adapter firmware for RP2040 by [Renze Nicolai]. This is a reimplementation of the ATTiny-based I2C-Tiny-USB project and complies to the same protocol – thus, it’s compatible with the i2c-tiny-usb driver that’s been in the Linux kernel for ages. Just drag&drop the .uf2, run a script on your Linux system, and you will get a /dev/i2c-X device you can work with from userspace code, or attach other kernel drivers to.

The software will work with any RP2040 devboard – just connect your I2C devices to the defined pins and you’ll have them show up in i2cdetect output on your Linux workstation. As a demo, [Renze] has written a userspace Python driver for one of these SSD1306 128×64 OLEDs, and gives us a commandline that has the driver accept output of an ffmpeg command capturing your main display’s contents, duplicating your screen on the OLED – in a similar fashion that we’ve seen with the “HDMI” I2C-driven display a few months back. Everything you might need is available on the GitHub page, including usage instructions and examples, and the few scripts you can use if you want to add an udev rule or change the I2C clock frequency.

Just to name a few purposes, you can use a Pi Pico as a tool for SWD, JTAG, CAN, a logic analyser with both digital and analog channels, or even as a small EMP-driven chip glitching tool. The now-omnipresent $3 Pi Pico boards, it seems, are a serious contender to fondly remembered hacker tools of the past, such as the legendary BusPirate.

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Welding Aluminum With A MIG Welder

October 29, 2022 by Al Williams 36 Comments

Steve Martin had a bit that was like a fake infomercial where he says, “You can be a millionaire and never pay taxes!” The instructions were, “First, get a million dollars. Then,…” [Brandon’s] instructions for how to convert your MIG welder to do aluminum for under $25 is not quite like that, but you do need the right kind of MIG welder to make it work. In particular, you need an actual MIG welder that has a provision to connect external gas. The instructions show a Hobart Handler 140 that meets the criteria and has sufficient power to handle aluminum.

The main task is to replace the liner for the torch. The stock liner is steel which is fine for its intended purpose, but it is too rough for aluminum wire. A PTFE liner is inexpensive and will work fine with the aluminum wire. If you want to do normal welding later, you’ll need to put the original liner back in.

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Two chillers side-by-side - the fake chiller on the left and the water fountain chiller (lid-less) on the right

Gutting And Upgrading Laser “Chiller” With No Chill

October 29, 2022 by Arya Voronova 10 Comments

Getting a cheap CO2 laser cutter is great for your workshop needs, and while you might get a weaker-than-declared laser tube, it’s still going to cut whatever you need to be cut. That might not be the case for the cooling equipment you’re getting alongside it, however, as [RealTimeKodi] shows in a post-project blogpost. They bought a CX3000 “chiller” and found out it had no chiller components (Nitter), only equipped with a radiator, a fan, and a pump.

Having your laser tube water be somewhat close to ambient temperature is something you can already achieve with an aquarium pump and a bucket of water — and it isn’t worth paying $100 for. Left with the sunk cost and an unfulfilled need for a proper chiller, [RealTimeKodi] started looking for paths to take – first one was using TEC elements. The upgrade process was fun, but the result was subpar, as the elements gobbled power with hardly any useful output to show for it.

[RealTimeKodi] didn’t give up, and eventually found an old water fountain chiller with chiller-like components inside, sold for $200. They could’ve used the water fountain as-is, but a few design issues and thirst for adventure got in the way, indisputably forcing them to stuff the fountain’s guts into the CX3000’s case.

Buying a laser cutter can sometimes feel like buying a 3D printer a decade ago — you get a K40, learn to use it, add the missing safety features, mod in autofocus, upgrade the control board, expand the work surface… That said, our experience shows that you don’t need any of those if A4-sized 3 mm wood cutting suit you, but a proper chiller is still worth its weight in gold-plated acrylic.

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Digital Kitchen Spoon Makes Weighing Your Ingredients A Snap

October 27, 2022 by Dan Maloney 14 Comments

There seem to be two camps when it comes to recipes: those based on volume-based measurements, and those based on the weight of ingredients. Gravimetric measurements have the advantage of better accuracy, but at the price of not being able to quickly scoop out a bit of this and a dash of that. It would be nice to get the convenience of volumetric measurements with the accuracy of weighing your ingredients, wouldn’t it?

It would, and that’s just what [Penguin DIY] did with this digital kitchen spoon scale. The build started with, perhaps not surprisingly, a large mixing spoon and a very small kitchen scale. The bowl of the spoon got lopped off the handle and attached to the strain gauge, which was removed from the scale along with its LCD display and circuit board. To hold everything, a somewhat stocky handle was fabricated from epoxy resin sandwiched between aluminum bolsters. Compartments for the original electronics parts, as well as a LiPo battery and USB charger module, were carved out of the resin block, and the electronics were mounted so that the display and controls are easily accessible. The video below shows the build as well as the spoon-scale in action in the kitchen.

We think this is not only a great idea but a fantastic execution. The black epoxy and aluminum look amazing together on the handle, almost like a commercial product. And sure, it would have been easy enough to build a scale from scratch — heck, you might even be able to do away with the strain gauge — but tearing apart an existing scale seems like the right move here.

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