Hackaday Podcast 056: Cat Of 9 Heads, Robot Squats, PhD In ESP32, And Did You Hear About Sonos?

Hackaday editors Elliot Williams and Mike Szczys gab on great hacks of the past week. Did you hear that there’s a new rev of the Pi 4 out there? We just heard… but apparently it’s release into the wild was months ago. Fans of the ESP8266 are going to love this tool that flashes and configures the board, especially for Sonoff devices. Bitluni’s Supercon talk was published this week and it’s a great roadmap of all the things you should try to do with an ESP32. Plus we take on the Sonos IoT speaker debacle and the wacky suspension system James Bruton’s been building into his humanoid robot.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

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A Simple Yet Feature-Packed Programmable DC Load

If you’ve got the hankering to own a lab full of high-end gear but your budget is groaning in protest, rolling your own test equipment can be a great option. Not everything the complete shop needs is appropriate for a DIY version, of course, but a programmable DC load like this one is certainly within reach of most hackers.

This build comes to us courtesy of [Scott M. Baker], who does his usual top-notch job of documenting everything. There’s a longish video below that covers everything from design to testing, while the link above is a more succinct version of events. Either way, you’ll get treated to a good description of the design basics, which is essentially an op-amp controlling the gate of a MOSFET in proportion to the voltage across a current sense resistor. The final circuit adds bells and whistles, primarily in the form of triple MOSFETS and a small DAC to control the set-point. The DAC is driven by a Raspberry Pi, which also supports either an LCD or VFD display, an ADC for reading the voltage across the sense resistor, and a web interface for controlling the load remotely. [Scott]’s testing revealed a few problems, like a small discrepancy in the actual amperage reading caused by the offset voltage of the op-amp. The MOSFETs also got a bit toasty under a full load of 100 W; a larger heatsink allows him to push the load to 200 W without releasing the smoke.

We always enjoy [Dr. Baker]’s projects, particularly for the insight they provide on design decisions. Whether you want to upgrade the controller for a 40-year-old game console or giving a voice to an RC2014, you should check out his stuff.

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Astra Readies Secretive Silicon Valley Rocket; Firm Exits Stealth Mode, Plans Test Launch

After the end of the Second World War the United States and the Soviet Union started working feverishly to perfect the rocket technology that the Germans developed for the V-2 program. This launched the Space Race, which thankfully for everyone involved, ended with boot prints on the Moon instead of craters in Moscow and DC. Since then, global tensions have eased considerably. Today people wait for rocket launches with excitement rather than fear.

That being said, it would be naive to think that the military isn’t still interested in pushing the state-of-the-art forward. Even in times of relative peace, there’s a need for defensive weapons and reconnaissance. Which is exactly why the Defense Advanced Research Projects Agency (DARPA) has been soliciting companies to develop a small and inexpensive launch vehicle that can put lightweight payloads into Earth orbit on very short notice. After all, you never know when a precisely placed spy satellite can make the difference between a simple misunderstanding and all-out nuclear war.

More than 50 companies originally took up DARPA’s “Launch Challenge”, but only a handful made it through to the final selection. Virgin Orbit entered their air-launched booster into the competition, but ended up dropping out of contention to focus on getting ready for commercial operations. Vector Launch entered their sleek 12 meter long rocket into the competition, but despite a successful sub-orbital test flight of the booster, the company ended up going bankrupt at the end of 2019. In the end, the field was whittled down to just a single competitor: a relatively unknown Silicon Valley company named Astra.

Should the company accomplish all of the goals outlined by DARPA, including launching two rockets in quick succession from different launch pads, Astra stands to win a total of $12 million; money which will no doubt help the company get their booster ready to enter commercial service. Rumored to be one of the cheapest orbital rockets ever built and small enough to fit inside of a shipping container, it should prove to be an interesting addition to the highly competitive “smallsat” launcher market.

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What Time Is It? Infinity Time

Since the dawn of the infinity craze, we’ve seen all kinds of projects — mirrors, smart mirrors, coffee tables, clocks, you name it. Unfortunately all of these cool projects sit at home, unappreciated by the public. Well, not anymore. [nolandoktor] is taking infinity to the streets with this beautiful and functional vortex watch.

Though this project is pretty darned advanced, it’s all open source and completely within reach for anyone who has the tools and the time. The watch is based around an ATmega32u4 and uses a DS3231 real-time clock to keep accurate time on the WS2812 LEDs that represent the numbers. The time is displayed using R, G, and B assigned to hour, minute, and second. Actually reading the time is bit tricky until you understand how the colors work together, but something this lovely deserves to maintain a slight air of mystery.

The watch’s case parts are all printed — metal for the bezel, and SLA for the white inner ring that lets a bit of light leak out the side in order to illuminate the USB port and the two stainless steel screws that act as touch contacts. In the future, [nolandoktor] wants to add flashlight mode that turns all the LEDs white, some gaskets to resist water, and wake-on-gesture functionality with an IMU. Take a second to check out the demo after the break.

If you prefer a more traditional timepiece of infinite interest, this clock moves more mundanely, but still looks cool.

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A Tetris To Be Proud Of, With Only A Nano

Tetris may have first arrived in the West on machines such as the PC and Amiga, but its genesis at the hands of [Alexey Pajitnov] was on an Electronika 60, a Soviet clone of an early-1970s DEC PDP-11. Thus those tumbling blocks are hardly demanding in terms of processor power, and a game can be implemented on the humblest of hardware. Relatively modern silicon such as the Atmega328 in [c0pperdragon]’s Arduino Nano Tetris console should then have no problems, but to make that assumption is to miss the quality of the achievement.

In a typical home or desktop computer of the 1980s the processor would have been assisted by plenty of dedicated hardware, but since the Arduino has none of that the feat of creating the game with a 288p video signal having four gray scales and with four-channel music is an extremely impressive one. Beside the Nano there are only a few passive components, there are no CRT controllers or sound chips to be seen.

The entire device is packaged within a clone of a NES controller, with the passives on a piece of stripboard beside the Nano. There is a rudimentary resistor DAC to produce the grey scales, and the audio is not the direct PWM you might expect but a very simple DAC created by charging and discharging a capacitor at the video line frequency. The results can be seen and heard in the video below the break, and though we’re sure we’ve heard something like that tune before, it looks to be a very playable little game.

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