An Ultrasound Driver With Open Source FPGAs

May 25, 2018 by 10 Comments

Ultrasound imaging has been around for decades, but Open Source ultrasound has not. While there are a ton of projects out there attempting to create open ultrasound devices, most of this is concentrated on the image-processing side of things, and not the exceptionally difficult problem of pinging a sensor at millions of times a second, listening for the echo, and running that through a very high speed ADC.

For his entry into the Hackaday Prize, [kelu124] is doing just that. He’s building an ultrasound board that’s built around Open Hardware, a fancy Open Source FPGA, and a lot of very difficult signal processing. It also uses some Rick and Morty references, so you know this is going to be popular with the Internet peanut gallery.

The design of the ultrasound system is based around an iCE40 FPGA, the only FPGA with an Open Source toolchain. Along with this, there are a ton of ADCs, a DAC, pulsers, and a high voltage section to drive the off-the-shelf ultrasound head. If you’re wondering how this ultrasound board interfaces with the outside world, there’s a header for a Raspberry Pi on there, too, so this project has the requisite amount of blog cred.

Already, [kelu] has a working ultrasound device capable of sending pulses out of its head and receiving the echo. Right now it’s just a few pulses, but this is a significant step towards a real, working ultrasound machine built around a reasonably Open Source toolchain that doesn’t cost several arms and legs.

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Biasing That Transistor: The Emitter Follower

May 25, 2018 by 29 Comments

We were musing upon the relative paucity of education with respect to the fundamentals of electronic circuitry with discrete semiconductors, so we thought we’d do something about it. So far we’ve taken a look at the basics of transistor biasing through the common emitter amplifier, then introduced a less common configuration, the common base amplifier. There is a third transistor amplifier configuration, as you might expect for a device that has three terminals: the so-called Common Collector amplifier. You might also know this configuration as the Emitter Follower. It’s called a “follower” because it tracks the input voltage, offering increased current capability and significantly lower output impedance.

The emitter follower circuit
The emitter follower circuit

Just as the common emitter amplifier and common base amplifier each tied those respective transistor terminals to a fixed potential and used the other two terminals as amplifier input and output, so does the common collector circuit. The base forms the input and its bias circuit is identical to that of the common emitter amplifier, but the rest of the circuit differs in that the collector is tied to the positive rail, the emitter forms the output, and there is a load resistor to ground in the emitter circuit.

As with both of the other configurations, the bias is set such that the transistor is turned on and passing a constant current that keeps it in its region of an almost linear relationship between small base current changes and larger collector current changes. With variation of the incoming signal and thus the  base current there is a corresponding change in the collector current dictated by the transistor’s gain, and thus an output voltage is generated across the emitter resistor. Unlike the common emitter amplifier this voltage increases or decreases in step with the input voltage, so the emitter follower is not an inverting amplifier.

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Hacking For Learning And Laughs: The Makers Of Oakwood School

May 25, 2018 by 3 Comments

The tagline of Bay Area Maker Faire is “Inspire the Future” and there was plenty of inspiration for our future generation. We have exhibits encouraging children to get hands-on making projects to call their own, and we have many schools exhibiting their student projects telling stories of what they’ve done. Then we have exhibitors like Oakwood School STEAM Council who have earned a little extra recognition for masterfully accomplishing both simultaneously.

[Marcos Arias], chair of the council, explained that each exhibit on display have two layers. Casual booth visitors will see inviting hands-on activities designed to delight kids. Less obvious is that each of these experiences are a culmination of work by Oakwood 7th to 12th grade students. Some students are present to staff activities and they were proud to talk about their work leading up to Maker Faire with any visitors who expressed interest.

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Hacking When It Counts: The Pioneer Missions

May 25, 2018 by 16 Comments

If the heady early days of space exploration taught us anything, it was how much we just didn’t know. Failure after failure mounted, often dramatic and expensive and sometimes deadly. Launch vehicles exploded, satellites failed to deploy, or some widget decided to give up the ghost at a crucial time, blinding a multi-million dollar probe and ending a mission long before any useful science was done. For the United States, with a deadline to meet for manned missions to the moon, every failure in the late 1950s and early 1960s was valuable, though, at least to the extent that it taught them what not to do next time.

For the scientists planning unmanned missions, there was another, later deadline looming that presented a rare opportunity to expand our knowledge of the outer solar system, a strange and as yet unexplored wilderness with the potential to destroy anything humans could build and send there. Before investing billions in missions to take a Grand Tour of the outer planets, they needed more information. They needed to send out some Pioneers.

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NASA Remotely Hacks Curiosity’s Rock Drill

May 25, 2018 by 64 Comments

We have a lot of respect for the hackers at NASA’s Jet Propulsion Laboratory (JPL). When their stuff has a problem, it is often millions of miles away and yet they often find a way to fix it anyway. Case in point is the Curiosity Mars rover. Back in 2016, the probe’s rock drill broke. This is critical because one of the main things the rover does is drill into rock samples, collect the powder and subject it to analysis. JPL announced they had devised a way to successfully drill again.

The drill failed after fifteen uses. It uses two stabilizers to steady itself against the target rock. A failed motor prevents the drill bit from retracting and extending between the stabilizers. Of course, sending a repair tech 60 million miles is not in the budget, so they had to find another way. You can see a video about the way they found, below.

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Bringing A VIC-20 Back From An Oily Grave

May 25, 2018 by 17 Comments

No matter which platform you’re into, retrocomputing is usually a labor of love. The obsolete, the unpopular, the downright weird – old computers of every stripe are found, restored to something like their former glory, and given a new lease on life. It’s heartwarming, in a way. But when a computer has obviously been abused, it takes a little extra effort, of a lot in the case of this oil-submerged VIC-20 restoration.

In the two-part video below, [The 8-Bit Guy] goes through the gory details of bringing this classic Commodore back from the grave. The first video shows the cosmetic rebuild, which given the filthy state of the machine was no mean feat. Cracked open, the guts were found to be filled with an oily residue; [The 8-Bit Guy] chalks that up to a past life in some kind of industrial setting, but we see it more as flood damage. Whatever the sad circumstances on the machine’s demise, the case required a workout to clean up, and it came out remarkably fresh looking. The guts needed quite a bit of cleaning too, mainly with brake cleaner to cut through the gunk.

Part two focuses on getting the machine running again, and here [The 8-Bit Guy] had his work cut out as well. With a logic probe, signal injector, and some good old-fashioned chip swapping, he was able to eliminate most of the potential problems before settling in on some RAM chips as culprits for the video problems he saw at power-up. It all worked out in the end, and the machine looks and acts like new. We’re impressed.

Maybe we shouldn’t question [The 8-Bit Guy]’s call on the VIC-20 being from an industrial setting, though. After all, the “little Amiga that could” ran a school’s HVAC system for over 30 years.

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Rey’s Blaster Shoots Glow-in-the-Dark Bullets

May 24, 2018 by 10 Comments

Youtuber and rubber band enthusiast [JoergSprave] is a big fan of Star Wars, and he loved the look of the blaster that Han Solo gave to Rey. He’d seen a few replicas of Rey NN-14 gun, but hadn’t seen any that actually fired anything, so he set out to make one that did.

The build itself is from plywood, with a paint job to make it look like an old blaster. What makes the build really cool is the bullets used: glow sticks! [Joerg] created space in the magazine for three glow sticks, so you’ve got a couple of shots before you have to reload. Crack ’em, load them up and then fire away!

The glow sticks give the blaster fire a great look (especially in the dark!) and it’s really easy to find the shots after you’ve fired them. We’ve featured [Joerg]’s builds a few times on the site, and his build videos are a lot of fun. Check out his compressed air crossbow bolt gatling gun, or his machete shooting slingshot.

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