# Building A High-Capacity Linear Servo Actuator

Linear actuators are useful things, moving things in straight lines rather than annoying circles like so many motors. [Retsetman] recently built a linear servo actuator of his own design with accurate positional control.

The design relies on a carriage that moves along a threaded rod, perhaps the most rudimentary design of linear actuator. A large brushed DC motor is used to turn the threaded rod through a 3D-printed 9:1 herringbone geartrain, shifting the actuator back and forth. End stop switches are used to disengage the motor to avoid damage to the mechanism. Feedback is via a ten-turn potentiometer driven off the output geartrain to match the range of the actuator to the rotational range of the pot.

The final build has a stroke of approximately 100 mm, and can lift and hold a 15 kg weight with ease. In a pull test, the actuator failed at a load just shy of 100 kg. If you’re looking for something smaller, though, you can try building a linear actuator out of old DVD drive parts instead. Video after the break.

# Hello (Many Quantum) World(s)

Historically, the first program you write for a new computer language is “Hello World,” or, if you are in Texas, “Howdy World.” But with quantum computing on the horizon, you need something better. Like “Hello Many Worlds.” [IonQ] proposes what that looks like and then writes it in seven different quantum languages in a post you should check out.

Here’s the description of the simple program:

The basic quantum program we’ll write is simple. It creates a fully-entangled state between two qubits, and then measures this state. This state is sometimes called a Bell State, or Bell Pair, after physicist John Stewart Bell.

The measurement results for this program should give us 0 for both qubits or 1 for both qubits, in equal amounts. When running these, we’ll be able to tell that we’re running on real hardware because that’s not always what we get! These errors are what currently limit quantum computers, but the first steps to overcome this with quantum error correction have already begun.

# Infinity Mirror Hypercrystal Is As Beautiful As It Sounds

Sometimes, we feature projects that are full to the brim with advanced functionality or solve some tricky little problem for the end-user. Other times, we feature stuff that just looks super damn cool, and the Infinity Mirror Hypercrystal is firmly in that latter category.

This show-stopping build comes to us from [Inanna Malick], who put together the design using algorithmic and generative art techniques she’s been working on for years. The form is a non-symmetrical, non-platonic solid, with each of its eight faces laser cut from mirrored acrylic. Plywood sections are used to hold together the structure.

Initially, the build was illuminated from within by white LEDs, but [Inanna] wasn’t satisfied with the look, which was too rooted in regular human technology. They were instead covered up with transparent dichroic tape, creating the lurid shifting colors that do so much to add to the mystery of the legendary Hypercrystal.

The result is an infinity mirror piece that looks more advanced, more alien, and more luridly enticing than most we’ve ever seen. The dichroic shift placed on the LEDs goes a long way to elevating this sculpture to new aesthetic heights. Video after the break.

# Unique Clock Is All Hands, No Dial, And Does The Worm

Back in the old days, we didn’t have fancy digital clocks. No, we had good analog clocks with a big hand and a little hand, and if you wanted to know the time you had to look at the clock and figure out which number each hand was pointing at, or kind of pointing at. It wasn’t easy, and we liked it that way.

So now, along comes an analog clock that’s nothing but the hands — no dial, no numbers, just hands. How is such a thing possible? The clue is in the clock’s name: AKUROBATTO, and in the video below, which shows the acrobatic movements of the clock’s hands as it does its thing. Serial improbable-clock maker [ekaggrat singh kalsi] clearly put a lot of thought into this mechanism, which consists of the hands and a separate base. The hands are joined together at one end and powered by small stepper motors. The base has two docking areas, where servo-driven claws can grasp the hand assembly, either at the center pivot or at the tip of either hand. With a little bit of shuffling around at transition points, the hands sweep out the hours and minutes in a surprisingly readable way.

For as cool as the design of AKUROBATTO is, the internals are really something else. There are custom-built slip rings to send power to the motors and the Arduinos controlling them, sensors to determine the position of each hand, and custom gearboxes for the steppers. And the locking mechanisms on the base are worth studying too — getting that right couldn’t have been easy.

All in all, an impressive build. Whether displaying the time on a phosphorescent screen or a field of sequins, it seems like [ekaggrat] has a thing for unique clocks. Continue reading “Unique Clock Is All Hands, No Dial, And Does The Worm”

# FPGA Starter Videos To Help Soften That Learning Curve

Digi-Key have been producing YouTube videos for a number of years now, and if you weren’t aware, they’re definitely worthy of some viewing time. The playlist we’re highlighting here is a pretty good introduction to FPGAs, specifically those supported by open source tools, with low cost hardware. If you’ve always wanted to get into hacking FPGA platforms, but don’t know where to start, this is going to be a big help. After first covering what an FPGA is and is not, and why you want to use one, [Shawn Hymel] dives in to the toolchain.

We’re really lucky that the bitstream for the Lattice iCE40 was reverse engineered by the super talented Claire (née Clifford) Wolf (AMP hour interview) which enabled the project ICEstorm toolchain to be created. Leveraging Yosys for synthesis and logic mapping, Icarus verilog coupled with GTKwave for simulation, netpnr for place and route and finally the project ICEstorm bitstream tools for packing into iCE40 format and loading onto the hardware. The whole toolchain flow is managed by APIO for simplicity, that is, provided your FPGA board is supported!

Of course, [Shawn] is using the low cost (for an FPGA) ICEStick by Lattice for this tutorial series, and they’re currently hard to get (you know why by now!) but, there are many other boards you could use. If you want to play with applications coupling a ARM micro to an FPGA, then the excellent BlackIce Mx is an option, but there are many other boards now with an decent micro nestled next to an FPGA and a few peripherals for convenience.

We should mention here, that project ICEstorm and the iCE40 is not the only show in town. Project Trellis has had our eye for a while, which targets the more complex Lattice ECP5 device. Yosys and friends do support more architectures, but the available flows usually require at least some vendor tool support at this time (looking straight at you, Xilinx) but as more devices get decoded, the open source tools will grow, and we will bring you that news!

What’s nice about this Digi-Key YT series, is that it doesn’t just cover the basic toolchain flow, then drop you in at the deep end of a big learning curve. There are videos covering subjects such as finite state machines (FSMs), test-benching and simulation, using embedded (block) memories, PLLs, harder subjects like dealing with metastability and clock-domain crossing (OK, he covers one technique – there’s more than one way to skin that particular cat) before finally looking at soft cores like the RISC-V. Lots to learn, and pretty well executed if you ask us! A Github version is available, for those who can’t stand watching the videos!

# Remoticon 2021 // Matt Venn Helps You Make ASICS

What would you make if you were given about ten square millimeters of space on a silicon wafer on a 130 nm process? That’s the exact question that the Open MPW program asks, and that [Matt Venn] has stepped up to answer. [Matt] came to Remoticon in 2020 to talk about his journey from nothing to his own ASIC, and he came back in 2021 to talk about what has happened in a year.

We expected great designs, but the variety of exciting and wonderful designs that have been submitted we think exceeded our expectations. [Matt] goes through quite a few of them, such as an analog neuron, a RISC-V Arduino-compatible microprocessor, and a satellite transceiver. Perhaps an unexpected side effect has been the artwork. Since the designs are not under an NDA, anyone can take the design and transform it into something gorgeous.

Of course, all of this hardware design isn’t possible without an open toolchain. There is an SRAM generator known as OpenRAM that can generate RAM blocks for your design. Coriolis2 is an RTL to GDS tool that can do placement and routing in VLSI. Finally, FlexCell is a cell library that tries to provide standard functions in a flexible, customizable way that cuts down on the complexity of the layout. There are GitHub actions that can run tests and simulations on PRs to keep the chip’s HDL in a good state.

However, it’s not all roses, and there was an error on the first run (MPW1). Hold time violations were not detected, and the clock tree wasn’t correct. This means that the GPIO cannot be set up, so the designs in the middle could be working, but without the GPIO, it is tricky to determine. With a regular chip, that would be the end, but since [Matt] has access to both the layout and the design, he can identify the problem and come up with a plan. He’s planning on overriding the IO setup shift register with an auxiliary microcontroller. (Ed Note: [tnt] has been making some serious progress lately, summarized in this video.)

It is incredible to see what has come from the project so far, and we’re looking forward to future runs. If this convinces you that you need to get your own ASIC made, you should check out [Matt]’s “Zero to ASIC” course.

# PendulumSynth Ties Music And Physics Together

Many musicians will be familiar with the metronome, a pendulum charged with generating a rhythmic tick to keep one’s performance in regular time. With PendulumSynth, [mrezanvari] takes the same basic pendulum but uses it in an altogether different musical way.

The build relies on a 10-inch plastic ball to serve as the weighted end of the pendulum, stuffed with a STM32F411CE BlackPill board, a BNO085 IMU, and an nRF radio module for sending out data for external processing. The pendulum’s motion is turned into MIDI data or CV for output to musical hardware which handles actually generating the output sounds.

The system operates in a variety of modes. Gravity mode outputs continuous MIDI data and CV relative to the continuous motion of the pendulum, while DIV3 mode tracks the pendulum’s motion and outputs 3 regular trigger points that correspond as such.

The combination of the intuitive physical nature of the pendulum and its sheer large size makes for an enticing musical exhibit. We’ve seen some other great musical installation pieces before, too. Video after the break.