Give 3D Printed Plastic A Well-Worn Metal Look

Affordable 3D printers let us turn ideas into physical reality without a big expensive workshop, but with their power came some disadvantages. The nature of FDM printers impart layer lines and nozzle ridges in the parts they produce. They can be minimized with optimized print settings, but never eliminated. [Emily Velasco] loves the power of 3D printing but not how the parts look. So she put in the effort to make 3D-printed plastic look like distressed metal and showed us how she did it. (Video also embedded after the break.)

This video is a follow-up to her Pet Eye project in response to feedback on Twitter. She had mentioned that the  salvaged metal box for Pet Eye wasn’t quite big enough to hold everything, so she had to extend its internal volume with a 3D print box on the back. It fit in so well that the offhand comment surprised many people who wanted to know more about how it was done. So she designed a demonstration cube covered with mechanical characteristics, and gave us this walkthrough of its transformation.

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Build-It-Yourself LC Meter

A basic digital multimeter (DMM) is usually the first measurement tool the aspiring electronics tinkerer buys. Even a bargain-bin DMM will happily measure voltage, current, and resistance; check continuity; and may even have a mode to measure transistor gain. Every toolbox needs at least one DMM, but most have an crucial limitation— they can’t measure two of the fundamental electrical quantities: inductance and capacitance. On Hackaday.io, [core weaver] has developed an open-source LC meter to allow you to build your own tool to measure inductance and capacitance.

[core weaver]’s design is all through-hole, so even just assembling one would be a great exercise for someone getting started in electronics. However, he didn’t just release a design, in a series of videos he goes through the theory of the device’s operation; explains the design of the circuit, firmware, and case; and shows you how to put it all together. For times when you need to measure a lot of parts (e.g. if you have to sort a bag of cheap capacitors looking for specific value), he’s even developed a desktop program to save you some trouble!

The finished meter looks incredible! If you want to build one for yourself, he’s put all of the files up on GitHub, and we highly recommend you check out his first video after the break. If you’d like to build yourself a 6.5-digit DMM to go with our LC Meter, consider this one which even has a home-built ADC.

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Remoticon Video: How To Use Machine Learning With Microcontrollers

Going from a microcontroller blinking an LED, to one that blinks the LED using voice commands based on a data set that you trained on a neural net work is a “now draw the rest of the owl” problem. Lucky for us, Shawn Hymel walks us through the entire process during his Tiny ML workshop from the 2020 Hackaday Remoticon. The video has just now been published and can be viewed below.

This is truly an end-to-end Hello World for getting machine learning up and running on a microcontroller. Shawn covers the process of collecting and preparing the audio samples, training the data set, and getting it all onto the microcontroller. At the end of two hours, he’s able to show the STM32 recognizing and responding to two different spoken words. Along the way he pauses to discuss the context of what’s happening in every step, which will help you go back and expand in those areas later to suit your own project needs.

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Network Booting The Pi 4

We’ve talked about PXE booting the Raspberry Pi 3B+, and then looked at the Raspberry Pi 4 as a desktop replacement. But there’s more! The Pi 4 sports a very useful new feature, the flashable bootloader. Just recently a beta version of that bootloader was released that supports PXE  — booting up over the network — which has become a must-have for those of us who have had consistently bad experiences with root filesystems on SD cards.

Pi with no SD CardWhat are the downsides, I hear you ask? You might see slower speeds going across the network compared to a high quality SD card, particularly with the Pi 4 and its improved SD card slot. PXE does require an Ethernet cable; WiFi is not enough, so you have that restriction to contend with. And finally, this isn’t a portable option — you are tethered to that network cable while running, and tethered to your network to boot at all.

On the other hand, if you’re doing a permanent or semi-permanent install of a Pi, PXE is absolutely a winner. There are few things worse than dragging a ladder out to access a Pi that’s cooked its SD card, not to mention the possibility that you firewalled yourself out of it. Need to start over with a fresh Raspbian image? Easy, just rebuild it on the PXE server and reboot the Pi remotely.

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Preserved Lemons On A Hacker’s Budget

“If you wish to make an apple pie from scratch, you must first invent the universe.” [Carl Sagan]. If you wish to make preserved lemons the same way as [Uri Tuchman], you have to start with that mentality. Video also below. The recipe for [Uri]’s preserved lemons involves two ingredients see sea salt, and sliced lemons, but we don’t expect you came here looking for a recipe and the food is less important than the journey.

Recipes take for granted that we have all the necessary utensils on hand, but what if you are missing one? What if you are missing all of them? Life’s lemons won’t get the best of us, and if we’re utensil-poor and tool-rich we will make those lemons regret trying to take a bite out of us. The first fixture for cutting lemons is a cutting board, then a knife, and finally an airtight container. We see him make all of them from stock material by hand. Does that seem like a lot of work? You forgot that if you’re going to eat up, you’ll need a serving platter and fork. If he ever opens a restaurant, don’t expect it to be fast food.

Maybe humans will only need one tool in the kitchen someday but at least one cat receives food from a single silicone-brained tool.

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Building A Foam Machine From A Leaf Blower And A Water Pump

Imagine a tub overflowing with bubble bath, except it’s a club dancefloor and music is pumping all night. This is what is known as a “foam party” — a wild and exciting concept that nonetheless many are yet to experience. The concept exploded in popularity in Ibiza in the 1990s, and foam parties are regularly held at nightclubs and festivals the world over.

Foam is generated with the obviously-named foam machine, and these can be readily purchased or hired for anyone wishing to host such an event. However, that’s not the hacker way. If you’re a little ingenious and take heed of the safety precautions, here’s how you can do it yourself.

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A Raspberry Pi Is A Hardware Hacker’s Swiss Army Knife

By now most of us have used a Raspberry Pi at some level or another. As a headless server it’s a great tool because of its price point, and as an interface to the outside world the GPIO pins are incredibly easy to access with a simple Python script. For anyone looking for guidance on using this device at a higher level, though, [Arun] recently created a how-to for using some of the Pi’s available communications protocols.

Intended to be a do-everything “poor man’s hardware hacking tool” as [Arun] claims, his instruction manual details all the ways that a Raspberry Pi can communicate with other devices using SPI and I2C, two of the most common methods of interacting with other hardware beyond simple relays. If you need to go deeper, the Pi can also be used as a full JTAG interface or SWD programmer for ARM chips. Naturally, UART serial is baked in. What more do you need?

As either a tool to keep in your toolbox for all the times you need to communicate with various pieces of hardware, or as a primer for understanding more intricate ways of using a Raspberry Pi to communicate with things like sensors or other computers, this is a great write-up. We also have more information about SPI if you’re curious as to how the protocol works.

Thanks to [Adrian] for the tip!