Measure The Speed Of A Speeding Bullet

May 4, 2020 by Danie Conradie 52 Comments

In the study of ballistics, you can do very little without knowing the velocity of a projectile. Whether you need to hit a target at over a mile, check if a paintball gun is safe for opposing players, or photograph high-velocity objects, you need a way to measure that velocity. [td0g] enjoys the challenge of photographing bullets impacts, and has created an open-source ballistic chronograph to help achieve this.

[td0g]’s design makes use of two light gates spaced some distance apart, and the time that an object takes to travel between the two is measured and used to calculate velocity. Most commercial ballistic chronographs also work in this way. [td0g] created the light gates using pairs of infrared photodiodes and LEDs. When there is a sudden dip in the amount of light received by the photodiode, the Arduino control circuit knows that an object has passed between the photodiode and LEDs and triggers the timer. An LCD shield on the Arduino is used to control the software and display velocity. As you probably guessed, clock accuracy is very important for such time measurements, and [td0g] demonstrates a simple technique using a smartphone metronome app to manually calibrate the clock to acceptable accuracy for his purposes. Continue reading “Measure The Speed Of A Speeding Bullet” →

Get Quarantine Fit With This Smart Pull-up Bar

May 4, 2020 by Tom Nardi 16 Comments

Most gyms are closed right now due to social distancing rules, which is what we’re using as our latest excuse to justify our sloth-like lifestyle. But apparently some people miss working out enough that they’re putting together impromptu home gyms. [Michael Pick] has even outfitted his DIY pull-up station with an Arduino to keep track of his exercise while on lockdown. You may not like it, but this is what peak performance looks like.

In the video after the break, [Michael] explains the design and construction of the bar itself which technically could be thought of as its own project. Obviously the Arduino counter isn’t strictly necessary, so if you just wanted to know how to put some scraps of wood and suitably beefy rod together in such a way that it won’t rip off the wall when you put your weight on it, this video is for you.

Towards the end of the video, he gets into an explanation of the electronic side of the project. Inside the 3D printed enclosure is an Arduino Pro Mini, a HC-SR04 ultrasonic sensor, and a 1602 serial LCD. Once the gadget has been mounted in the proper position and activated, it will count how many pull-ups [Michael] has done on the screen.

While we historically haven’t seen a whole lot in the way of homebrew exercise equipment, the current COVID-19 situation does seem to be getting the adrenaline flowing for some of you. We recently covered some DIY dumbbells made from hardware store finds that would be an excellent first project for any hackers who’ve recently been ejected from the Matrix and are trying to use their muscles for the first time.

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Tips From A Former Niche Item Etsy Store

May 4, 2020 by Donald Papp 4 Comments

Etsy is a service aimed at providing a way for makers of handmade items to sell them online. [Bithead] closed up shop earlier this year and wrote up an interesting perspective on what did and didn’t work out. The main market for [Bithead]’s store was Star Wars cosplayers, because it all started with some Star Wars inspired com pads, some of which are pictured here.

One thing [Bithead] felt worked well overall was to “think big, start small, and scale fast.” In essence, bootstrap things by selling inventory on hand and carefully monitoring demand, then if demand is sustained, ramp up to larger batches, which are more efficient. The risk of making larger part orders and carrying more stock on hand is offset by the reliable demand. Waiting until solid data on reliable demand is available means missing out on early sales, but it’s a low risk approach that works well for niche products that have little or no real competition.

A couple things that didn’t work out were efforts to follow Etsy’s advice to add more products to attract a wider audience, and to try out tools for offering discounts and incentives aimed at turning abandoned carts into sales. Neither went well. The first resulted in adding items that sold poorly, diluted the focus of the store, and incurred a cost for each listing. The second never seemed to have any impact on sales whatsoever. Perhaps there is a place for these efforts, but [Bithead]’s niche market wasn’t it.

It’s a good read about how things went for an Etsy store that served a niche audience over three years. The perspective and experiences might be useful to anyone looking to turn a bright idea into something sold online, so if you’re at all interested, take a few minutes to check it out.

We’ve seen [Bithead]’s work before, this lightsaber-inspired violin bow was one project that went on to become a kit for sale.

The Vaccine Factory Inside You: RNA Vaccine Basics

May 4, 2020 by Dan Maloney 19 Comments

As the world pulls back from the acute phase of the COVID-19 pandemic, it enters what will be perhaps a more challenging time: managing the long-term presence of the SARS-CoV-2 virus that causes the disease. In the roughly two-century history of modern vaccination practices, we’ve gotten pretty good at finding ways to protect ourselves from infectious diseases, and there’s little doubt that we’ll do the same for SARS-CoV-2. But developing a vaccine against any virus or bacterium takes time, and in a pandemic situation, time is exactly what’s at a premium.

In an effort to create an effective vaccine against this latest viral threat, scientists and physicians around the world have been taking a different approach to inoculation. Rather than stimulating the immune system in the usual way with a weakened sample of the virus, they’re trying to use the genetic material of the virus to stimulate an immune response. These RNA vaccines are a novel approach to a novel infection, and understanding how they work will be key to deciding whether they’ll be the right way to attack this pandemic.

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ESP32-S2 Hack Chat With Adafruit

May 4, 2020 by Dan Maloney 23 Comments

Join us on Wednesday, May 6 at noon Pacific for the ESP32-S2 Hack Chat with Limor “Ladyada” Fried and Scott Shawcroft!

When Espressif released the ESP8266 microcontroller back in 2014, nobody could have predicted how successful the chip was to become. While it was aimed squarely at the nascent IoT market and found its way into hundreds of consumer devices like smart light bulbs, hackers latched onto the chip and the development boards it begat with gusto, thanks to its powerful microcontroller, WiFi, and lots of GPIO.

The ESP8266 was not without its problems, though, and security was always one of them. The ESP32, released in 2016, addressed some of these concerns. The new chip added another CPU core, a co-processor, Bluetooth support, more GPIO, Ethernet, CAN, more and better ADCs, a pair of DACs, and a host of other features that made it the darling of the hacker world.

Now, after being announced in September of 2019, the ESP32-S2 is finally making it into hobbyist’s hands. On the face of it, the S2 seems less capable, with a single core and neither Bluetooth nor Ethernet. But with a much faster CPU, scads more GPIO, more ADCs, a RISC-V co-processor, native USB, and the promise of very low current draw, it could be that the ESP32-S2 proves to be even more popular with hobbyists as it becomes established.

To talk us through the new chip’s potential, Limor “Ladyada” Fried and Scott Shawcroft, both of Adafruit Industries, will join us on the Hack Chat. Come along and learn everything you need to know about the ESP32-S2, and how to put it to work for you.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, May 6 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
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Doom Clone Shows What An Alternate-Reality Amiga Could’ve Had

May 4, 2020 by Erin Pinheiro 31 Comments

Can you run Doom on the Amiga? No, not really, and arguably that was one of the causes for the computer’s demise in the mid-90s as it failed to catch up on the FPS craze of the PC world. [Krzysztof Kluczek] of the Altair demogroup has managed not exactly to remedy that status with the original article, but to show us how a potential contender could’ve been designed for the unexpanded Amiga hardware back in the day.

Many developers tried to emulate the thrill and ambiance of the id Software shooter, but they all required high-end Amigas with faster processors and expanded memory, limiting their player base on an already diminished demographic. Not only that, but even with fancier hardware, none of them quite managed to match how well Doom ran on your run-of-the-mill 486 at the time. [Krzysztof] isn’t trying to port Doom itself, but instead creating an engine custom-designed to take advantage of, and minding the limitations of the OCS Amiga as it existed in 1987. The result is Dread, a 2.5D engine that resembles the SNES port of Doom and uses assets from the Freedoom project in order to remain copyright-abiding.

It might not be Doom, but it’s a good peek at what the 33-year old hardware could’ve done in the right hands back then. Technically it already surpasses what the Wolfenstein 3D engine could do, so there’s an idea if someone ever aims to make a straight up port instead of their own game. If you like seeing Doom run on machines it wasn’t meant to, boy do we have some posts for you. Otherwise, stick around after the break for two videos of Dread’s engine being demonstrated.

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Time Enough At Last: Reviving An Heirloom Typewriter

May 4, 2020 by Erin Pinheiro 28 Comments

You may find yourself living in interesting times. The world we knew two months ago is gone, and there is time enough at last, to finally go through those projects we’ve been putting off for one reason or another. Today, I wanted to explore and possibly repair an old unidentified typewriter that belonged to my late aunt for many decades.

A small disclaimer though, I am not an avid typewriter collector or connoisseur. I enjoy looking at them and using them, but by no stretch of the imagination I want to claim to be an expert in their history or inner workings — I’m a hacker after all. What follows is a layman’s adventure into her first typewriter repair, an exciting tale that explores typewriter anatomy and troubleshooting. Let’s dig in.

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