If you are below a certain age, you’ve probably never heard of a Q multiplier. This is a device that increases the “Q” of a radio receiver’s intermediate frequency and, thus, provide a higher selectivity. If you enjoy nostalgia, you can see inside a 1960s-era Heathkit QF-1 Q multiplier in [Jeff’s] informative video, below.
The Q multiplier was a regenerative amplifier that operated at just below the oscillation point. This provided very high amplification for the frequency of interest and less amplification for other frequencies. Some radios had a stage like this built-in, but the QF-1 was made to add into an external radio. For some Heathkit receivers, there was a direct plug to tap into the IF stage for this purpose. Othe radios would require some hacking to get it to work.
The QF-1 had several modes of operation where it could act as bandpass filter or a notch filter. You could also tune the frequency using the main knob. The circuit when revealed isn’t overly complex and there is no printed circuit board. The active device was a dual triode.
If you want a deeper discussion of the circuit, the Orange County Amateur Radio Club newletter a few years back had a great article on this device by [AF6C]. It explains how each mode works. It also mentions a few of the device’s offspring such as the HD-11 and GD-125, which was sold until 1971.
If you have plans of building a circuit like this, keep in mind that the intermediate frequency for most radios in those days was 455 kHz, which is what the QF-1 expects. Most communication receivers today use significantly higher IF for a variety of reasons (10.7 MHz, for example, is common).
We always enjoy [Jeff’s] videos of old receivers and gear. Not that he’s the only one doing things like that.
This bag was designed to show off the capabilities of Loomia, a line of prototyping parts made with e-textiles and other flexible applications in mind. It can be sewn, fused, or adhered to various substrates including fabric and wood. [AmpedAtelier] is using a Beetle microcontroller to control RGB LED strips using an illuminated Loomia soft switch on the strap. The switch is wired to the microcontroller through Loomia busses running through the strap.
[David] bought the iPod with a dead battery, so when he opened the iPod to get the old battery out, he noticed there was enough space to fit a USB-C connector. The original Apple 30 pin connector runs USB 2.0 through four of the pins, so [David] used the original USB cable and identified the appropriate pins and traces with a continuity tester. The connector was destructively removed with side cutters, ripping off all but one of the pads in the process. A hot air station might have made things easier, but we assume he did not have one on hand. The USB-C connector was scavenged from a cheap USC-C to USB Micro adaptor and mounted by soldering the housing directly to the PCB’s ground plane. The three remaining terminals were soldered to the traces with enamel wire.
With the new battery installed, [David] confirmed that both charging and data transfer worked. The IC that handles the button and scroll pad interfered slightly with the new connector, so he filed away some of the IC’s excess. Any open pads close to the new connector was covered with Kapton tape to avoid shorts. The large hole in the enclosure for the 30 pin connection was partly filled in with five-minute epoxy. The final assembled product looks almost factory produced and works as it’s supposed to, so we call this a win.
Retrofitting USB-C connectors in various electronic devices has become a popular hack over the past two years. We’ve seen it done on everything from Thinkpads to soldering irons.
The United Kingdom is somewhat unique in the world for requiring those households which view broadcast television to purchase a licence for the privilege. Initially coming into being with the Wireless Telegraphy Act in 1923, the licence was required for anyone receiving broadcast radio, before being expanded to cover television in 1946. The funds generated from this endeavour are used as the primary funding for the British Broadcasting Corporation.
Of course, it’s all well and good to require a licence, but without some manner of enforcement, the measure doesn’t have any teeth. Among other measures, the BBC have gone as far as employing special vans to hunt down illegally operating televisions and protect its precious income.
The Van Is Coming For You
To ensure a regular income, the BBC runs enforcement operations under the TV Licencing trade name, the entity which is responsible for administering the system. Records are kept of licences and their expiry dates, and investigations are made into households suspected of owning a television who have not paid the requisite fees. To encourage compliance, TV Licencing regularly sends sternly worded letters to those who have let their licence lapse or have not purchased one. In the event this fails, they may arrange a visit from enforcement officers. These officers aren’t empowered to forcibly enter homes, so in the event a homeowner declines to cooperate with an investigation, TV Licencing will apply for a search warrant. This may be on the basis of evidence such as a satellite dish or antenna spotted on the roof of a dwelling, or a remote spied on a couch cushion through a window.
Alternatively, a search warrant may be granted on the basis of evidence gleaned from a TV detector van. Outfitted with equipment to detect a TV set in use, the vans roam the streets of the United Kingdom, often dispatched to addresses with lapsed or absent TV licences. If the van detects that a set may be operating and receiving broadcast signals, TV Licencing can apply to the court for the requisite warrant to take the investigation further. The vans are almost solely used to support warrant applications; the detection van evidence is rarely if ever used in court to prosecute a licence evader. With a warrant in hand, officers will use direct evidence such as a television found plugged into an aerial to bring an evader to justice through the courts.
Detecting Television Usage
An example of the original detector van design, as deployed in 1952. Note the three loop antennas – one front, two rear.
The vans were first deployed in 1952, with equipment designed to pick up the magnetic field from the horizontal deflection scanning of the picture tube, at 10.125 KHz. Loop antennas were used to detect the second harmonic of this signal at 20.25 KHz, which was mixed with a local beat frequency oscillator at 19.25 KHz to create a 1 KHz tone to indicate to the operator when a signal was picked up. Three antennas were used, one on the front of the van and two on the rear on the left and right sides. When the van was next to an operating television in a house, the signal between the front and side antenna would be roughly the same. Signal from the right and left antennas could then be compared to determine which side of the street the television was on.
The VHF era brought with it a new detector van design, this time built on a car such as to avoid clearance issues with the tall antenna.
Once ITV started broadcasting in 1963, this method of detection became impractical. The two television stations did not synchronise their line-scan signals, so neighbouring houses watching different channels would create confusing interference for the detector. To get around this, the vans switched to detecting the local oscillator of the TV set’s superheterodyne VHF receiver instead. With stations broadcasting on bands spanning 47 to 240 MHz, it was impractical at the time to build a tuner and antenna to cover this entire range. Instead, the equipment was designed to work from 110-250MHz tuning in the fundamental frequencies of the higher bands, or the harmonics of the lower frequency oscillators. A highly directional antenna was used to hone in on a set, and a periscope was installed to allow the operator to view the house the antenna was pointing at. If operating in the dark, the periscope could instead be used to shine a small dot of light in the direction of the antenna’s facing, to identify the relevant target. Results were cross-referenced with a list of houses with lapsed or absent licences to help hunt down evaders.
A pair of antennas was used to search for televisions in the UHF era, with the twin setup helping to improve directionality.
The introduction of UHF transmissions led to further redesigns. Engineers again leaned on harmonics to allow a single system to cover the full range from low VHF to higher UHF frequencies. A pair of 6′ long log-periodic spiral antennas were used, mounted on top of the van, which could be varied in spacing to effectively tune different frequencies. In practice, the antennas would be pointed towards a row of houses, while the van was slowly driven along the street. The beam pattern of the antenna pair would show seven distinct lobes on a CRT inside the van when a TV was detected. An operator would press a button to mark house boundaries on the CRT as the van moved, and when the lobe pattern centered on a particular house, the TVs location was clear. The hardware was further refined over the years, with various antenna rigs and detection equipment used as technology marched on.
Seeking Television in Modern Times
In the UHF era, pinning down a detected television set took some finesse, with the operator having to interpret signals received on a CRT display.
Modern efforts to detect licence evasion are shrouded in mystery. Modern flatscreen displays receiving digital television signals do not emit as much radio frequency interference as older designs, and any such signals detected are less easily correlated with broadcast television. An LCD television in the home can just as easily be displaying output from a video game console or an online streaming service, with both being usage cases that do not require the owner to pay a licence fee. Based on an alleged BBC submission for a search warrant in recent years, there may be optical methods used in which reflected light from a television in a viewer’s home is compared to a live broadcast signal. The BBC declined to answer the Freedom of Information request with any details of their methods, other than to say they have employed vehicles and handheld devices in enforcement efforts. However, given the multitude of broadcast, cable and satellite channels now available, the comparison effort would necessarily be much harder, leading some to suspect the days of the detector van are largely over.
While the TV licence may have its days numbered with the increased dominance of streaming content, it remains a quirky piece of legislation that spawned the development of a technical curiosity. If you fancy yourself a television sleuth, sound off in the comments with your chosen approach to hunting for televisions watching broadcast content illegally in this modern era. And be sure to look over your shoulder – you never know when TV Licencing might be knocking on your door!
The United Kingdom is somewhat unique in the world for requiring those households which view broadcast television to purchase a licence for the privilege. Initially coming into being with the Wireless Telegraphy Act in 1923, the licence was required for anyone receiving broadcast radio, before being expanded to cover television in 1946. The funds generated from this endeavour are used as the primary funding for the British Broadcasting Corporation.
Of course, it’s all well and good to require a licence, but without some manner of enforcement, the measure doesn’t have any teeth. Among other measures, the BBC have gone as far as employing special vans to hunt down illegally operating televisions and protect its precious income.
The Van Is Coming For You
To ensure a regular income, the BBC runs enforcement operations under the TV Licencing trade name, the entity which is responsible for administering the system. Records are kept of licences and their expiry dates, and investigations are made into households suspected of owning a television who have not paid the requisite fees. To encourage compliance, TV Licencing regularly sends sternly worded letters to those who have let their licence lapse or have not purchased one. In the event this fails, they may arrange a visit from enforcement officers. These officers aren’t empowered to forcibly enter homes, so in the event a homeowner declines to cooperate with an investigation, TV Licencing will apply for a search warrant. This may be on the basis of evidence such as a satellite dish or antenna spotted on the roof of a dwelling, or a remote spied on a couch cushion through a window.
Alternatively, a search warrant may be granted on the basis of evidence gleaned from a TV detector van. Outfitted with equipment to detect a TV set in use, the vans roam the streets of the United Kingdom, often dispatched to addresses with lapsed or absent TV licences. If the van detects that a set may be operating and receiving broadcast signals, TV Licencing can apply to the court for the requisite warrant to take the investigation further. The vans are almost solely used to support warrant applications; the detection van evidence is rarely if ever used in court to prosecute a licence evader. With a warrant in hand, officers will use direct evidence such as a television found plugged into an aerial to bring an evader to justice through the courts.
Detecting Television Usage
An example of the original detector van design, as deployed in 1952. Note the three loop antennas – one front, two rear.
The vans were first deployed in 1952, with equipment designed to pick up the magnetic field from the horizontal deflection scanning of the picture tube, at 10.125 KHz. Loop antennas were used to detect the second harmonic of this signal at 20.25 KHz, which was mixed with a local beat frequency oscillator at 19.25 KHz to create a 1 KHz tone to indicate to the operator when a signal was picked up. Three antennas were used, one on the front of the van and two on the rear on the left and right sides. When the van was next to an operating television in a house, the signal between the front and side antenna would be roughly the same. Signal from the right and left antennas could then be compared to determine which side of the street the television was on.
The VHF era brought with it a new detector van design, this time built on a car such as to avoid clearance issues with the tall antenna.
Once ITV started broadcasting in 1963, this method of detection became impractical. The two television stations did not synchronise their line-scan signals, so neighbouring houses watching different channels would create confusing interference for the detector. To get around this, the vans switched to detecting the local oscillator of the TV set’s superheterodyne VHF receiver instead. With stations broadcasting on bands spanning 47 to 240 MHz, it was impractical at the time to build a tuner and antenna to cover this entire range. Instead, the equipment was designed to work from 110-250MHz tuning in the fundamental frequencies of the higher bands, or the harmonics of the lower frequency oscillators. A highly directional antenna was used to hone in on a set, and a periscope was installed to allow the operator to view the house the antenna was pointing at. If operating in the dark, the periscope could instead be used to shine a small dot of light in the direction of the antenna’s facing, to identify the relevant target. Results were cross-referenced with a list of houses with lapsed or absent licences to help hunt down evaders.
A pair of antennas was used to search for televisions in the UHF era, with the twin setup helping to improve directionality.
The introduction of UHF transmissions led to further redesigns. Engineers again leaned on harmonics to allow a single system to cover the full range from low VHF to higher UHF frequencies. A pair of 6′ long log-periodic spiral antennas were used, mounted on top of the van, which could be varied in spacing to effectively tune different frequencies. In practice, the antennas would be pointed towards a row of houses, while the van was slowly driven along the street. The beam pattern of the antenna pair would show seven distinct lobes on a CRT inside the van when a TV was detected. An operator would press a button to mark house boundaries on the CRT as the van moved, and when the lobe pattern centered on a particular house, the TVs location was clear. The hardware was further refined over the years, with various antenna rigs and detection equipment used as technology marched on.
Seeking Television in Modern Times
In the UHF era, pinning down a detected television set took some finesse, with the operator having to interpret signals received on a CRT display.
Modern efforts to detect licence evasion are shrouded in mystery. Modern flatscreen displays receiving digital television signals do not emit as much radio frequency interference as older designs, and any such signals detected are less easily correlated with broadcast television. An LCD television in the home can just as easily be displaying output from a video game console or an online streaming service, with both being usage cases that do not require the owner to pay a licence fee. Based on an alleged BBC submission for a search warrant in recent years, there may be optical methods used in which reflected light from a television in a viewer’s home is compared to a live broadcast signal. The BBC declined to answer the Freedom of Information request with any details of their methods, other than to say they have employed vehicles and handheld devices in enforcement efforts. However, given the multitude of broadcast, cable and satellite channels now available, the comparison effort would necessarily be much harder, leading some to suspect the days of the detector van are largely over.
While the TV licence may have its days numbered with the increased dominance of streaming content, it remains a quirky piece of legislation that spawned the development of a technical curiosity. If you fancy yourself a television sleuth, sound off in the comments with your chosen approach to hunting for televisions watching broadcast content illegally in this modern era. And be sure to look over your shoulder – you never know when TV Licencing might be knocking on your door!
We spend a lot of time looking at retrocomputing in the form of gaming and home computers, but it’s true to say that minicomputers are less common than hardware projects. Perhaps it’s the size, cost, or even relative rarity of the original machines, but DEC minicomputers are a bit unusual around here. [Sprite_TM] hasn’t bought us a PDP11 or a VT102 terminal, but he’s done the next best thing in the form of a miniature working VT102 that also conceals a PDE11 emulator. It runs Tetris, which was originally developed on a Russian clone of the PDP11 architecture, and the 2.1BSD operating system.
Powering it all is an ESP32 module, and the PDP11 emulator is the well-known SIMH software. Porting this to the slightly limited environment of the microcontroller required a few compromises, namely the network stack and the configuration interface. In a particularly clever move [Sprite_TM] enabled BSD networking by writing an ESP32 layer that takes network packets via SIMD directly from BSD. It includes its own DHCP client and wireless network configuration tool, allowing an ancient UNIX-derived operating system from the 1970s to connect to the 21st century Internet through an emulator with its network code stripped out.
The case is a masterwork in OpenSCAD, a complete VT102 unit in miniature with a tiny LCD screen that when printed on a resin printer is a remarkable facsimile of the real thing. It doesn’t have a keyboard counterpart, but even with a miniature Bluetooth ‘board it still looks pretty impressive. In the video below the break he boots it into 2.1BSD, and importantly since it is a server operating system, logs into it from his laptop and plays a game of Zork.
Like many of us, [Michael] needed a way to let the family know whether pants are required to enter the room — in other words, whenever a videoconference is in progress. Sure he could hang a do not disturb sign, but those are easy to forget. There’s no need to worry about forgetting to change status because this beautiful wall-mounted sign can be controlled with Alexa.
Inside the gorgeous box made from walnut, curly maple, and oak is an ESP32, some RGB LEDs, and three MOSFETs. [Michael] is using the fauxmoESP library to interface the ESP32 with Alexa, which emulates a Phillips Hue bulb for the sake of using a protocol she already knows. [Michael] can change the color and brightness percentage with voice commands.
The sign is set up as four different devices — one default, and one for each color. Since talking to Alexa isn’t always appropriate, [Michael] can also change the color of the LEDs using sliders on a website that’s served up by the ESP. Check out the full build video after the break.
[Clive] had an interesting video about LED lights from Philips. You can’t buy them unless you live in Dubai. Apparently inspired by the ruler of Dubai, Sheikh Mohammad Bin Rashid Al Maktoum, who wanted more efficient and longer-lasting bulbs. The secret? A normal LED bulb uses an LED “filament” at 1 watt each. The Dubai bulbs run at about a fourth of that which means they need more LEDs to get the same amount of light, but they should last longer and operate more efficiently.
After exploring the brightness and color of different lamps, [Clive] tears one up and finds some surprises inside. The LEDs get over 200V each and the driver circuit has a lot of pairs of components, possibly to keep the size small for the high voltages involved, although it could be to improve reliability, [Clive] wasn’t sure.
By reducing the power, [Clive] was able to count that each LED strip contains 21 LEDs. He also notes some of the oddities in construction that appear to be for reliability and ease of manufacturing. We aren’t sure how that compares to the construction of conventional bulbs. The circuit includes a bridge rectifier and a linear current regulator using a MOSFET.
The bulbs cost a bit more, but if you factor in the probable long life, their total cost over time should be reasonable. Overall, it is interesting that a nice design came from what amounts to government regulation. Of course, there is a price: in exchange for the development of the bulbs, Philips has the exclusive right to make and sell the bulbs for the next several years. They expect to sell 10 million lamps by the end of 2021, although they are only available, currently, in Dubai.
The donor keyboard is a nondescript late-80s AT compatible PC. Before readers imagine that a sought-after mechanical ‘board is being defiled, these were manufactured in their millions back then with exactly the same lackluster actions as modern cheap input devices. This one had plenty of space inside for an Arduino Nano that emulates an AT keyboard host and plays WAV file samples from an SD card to one of its PWM outputs. An op-amp low pass filter cleans up the noise from this rudimentary DAC, and feeds a little speaker through an audio amplifier. The keyboard supports both male and female voices, as well as a piano.
Hours of juvenile fun will no doubt result, but we can’t help wondering whether this could become the bane of a parent’s life in the manner of so many other noise-producing toys. Meanwhile, [Peter]’s work has graced these pages in the past, most recently with an automatic cooker hood.
Sad news from Mars, where the InSight lander’s “mole” was officially declared dead. The self-drilling probe, the centerpiece of the Heat Flow and Physical Properties Package (HP3) experiment, was designed to ram itself 5 meters into the Martian regolith while deploying a sensor-laden tail. The mole would then explore heat flow from within the planet. But the unexpected properties of the soil beneath the lander, including lower-than-expected friction on the hull of the mole and a cement-like “duricrust” layer, confounded the probe’s downward progress for the last two years. We covered the design of the mole, which is similar to an impact drill, as well as the valiant efforts to save the mission, but after one last try on January 9 where the mole gave 500 more whacks without any progress, controllers threw in the towel. It just goes to show that space travel and exploration are anything but routine, and that there’s far, far more we don’t know about even our nearest solar neighbor than what we do know.
Sad news, too, from closer to home, this time — Ohio, to be exact: the 2021 Hamvention has been canceled. It’s not exactly a surprise given the ongoing COVID-19 pandemic, but it’s still a blow to have ham radio’s biggest party canceled for two years running. We expect a lot of cons and meetings will suffer a similar fate in 2021. We’ll be sure to bring you any announcements we hear about.
One event that hasn’t been canceled is iQuHACK, a quantum hackathon hosted by MIT. We don’t pretend to fully understand quantum computing, or even to have scratched the surface of the subject in any meaningful way. Following up on what comes out of iQuHACK after it runs next weekend might be interesting for the quantum-curious, though. But really, just the fact that we’re in an age where quantum hackathons are a thing is pretty cool.
Back on the COVID-19 theme, managing editor Elliot Williams gave us the heads up on a story about gorillas at the San Diego Zoo Safari Park testing positive for the virus. It’s not exactly surprising that some of our evolutionarily closest relatives would be susceptible to the disease, and it’s not exactly a funny story, but the conversation in the morning meeting at the zoo must have been priceless:
“Hey, that gorilla looks sick. We’d better test him for COVID.”
“Yeah, probably. Here’s the brain-tickling swab, you go stick it up his nose.”
“Nu-uh, you stick it up his nose!”
“Nope. Hey, where’s the intern?”
And speaking of dangerous work environments, behold yet another classic of corporate safety propaganda: The Color of Danger. Like Shake Hands with Danger, this film was produced by heavy equipment manufacturer Caterpillar. But this time, instead of concentrating on the various opportunities maintaining heavy equipment presents for traumatic amputations, the subject matter is forklift safety. We’ve spent a fair number of hours in the driver’s seat of a lift truck, so we know full well how quickly things can go wrong, and this film does a great job of showing a lot of them. But what you’ve got to admire is the trick driving and stunt work that went into these vignettes; not too many people can pull off forklift drifting safely (12:30), and putting the truck in the drink without drowning was a neat trick (13:00). And of course, with any film on forklift safety, we’d be remiss not to tip our hardhat to Staplefahrer Klaus and his oft-bloodied co-workers.
To say the TRS-80 Model 100 was ahead of its time would be something of an understatement. It had a high-quality mechanical keyboard, phenomenal battery life, plenty of I/O and expansion capabilities, and was actually small and light enough to easily carry around. While its layout might seem to be a bit dated to modern eyes, there’s little debate that it was one of the most successful and influential computers in history.
So it’s little surprise that [belsamber] thought the Model 100 might make an ideal platform for his mobile command line work. With a few modifications, naturally. While technically the nearly 40 year old portable could connect to a Linux computer as a simple serial terminal, its outdated and non-backlit LCD leaves a bit to be desired in 2021. But there’s little sense in upgrading the display if he’d still be saddled with the anemic Intel 80C85 motherboard, so he decided to clean house and replace everything.
Once stripped of the original hardware, the Model 100’s enclosure offered up plenty of room for a Pine A64 LTS single-board computer, four 18650 cells, and a 1920×480 ultra-wide LCD. While not a perfect match for the dimensions of the original panel, the new screen is an exceptionally close fit. The keyboard has been left intact, but rather than adding a QMK-compatible microcontroller to the mix, [belsamber] wired the matrix directly into the GPIO of the A64.
While we know some retro aficionados might shed a tear to see an iconic computer get gutted, [belsamber] mentions that nothing will go to waste; the parts he pulled from this machine will serve as spares for a second Model 100 he has in his collection. Besides, given the immense popularity of these machines, they aren’t exactly rare to begin with.
To say the TRS-80 Model 100 was ahead of its time would be something of an understatement. It had a high-quality mechanical keyboard, phenomenal battery life, plenty of I/O and expansion capabilities, and was actually small and light enough to easily carry around. While its layout might seem to be a bit dated to modern eyes, there’s little debate that it was one of the most successful and influential computers in history.
So it’s little surprise that [belsamber] thought the Model 100 might make an ideal platform for his mobile command line work. With a few modifications, naturally. While technically the nearly 40 year old portable could connect to a Linux computer as a simple serial terminal, its outdated and non-backlit LCD leaves a bit to be desired in 2021. But there’s little sense in upgrading the display if he’d still be saddled with the anemic Intel 80C85 motherboard, so he decided to clean house and replace everything.
Once stripped of the original hardware, the Model 100’s enclosure offered up plenty of room for a Pine A64 LTS single-board computer, four 18650 cells, and a 1920×480 ultra-wide LCD. While not a perfect match for the dimensions of the original panel, the new screen is an exceptionally close fit. The keyboard has been left intact, but rather than adding a QMK-compatible microcontroller to the mix, [belsamber] wired the matrix directly into the GPIO of the A64.
While we know some retro aficionados might shed a tear to see an iconic computer get gutted, [belsamber] mentions that nothing will go to waste; the parts he pulled from this machine will serve as spares for a second Model 100 he has in his collection. Besides, given the immense popularity of these machines, they aren’t exactly rare to begin with.
After early experiments with supervised learning, [Yosh] decided to implement a genetic algorithm to produce an AI to drive in the game. The AI takes distance from the track walls as an input, and has steering and accelerator values as an output. Starting with 100 AIs in generation 1, [Yosh] iterated by choosing the AIs that covered the longest distance in 13 seconds. Once the AIs started to get the hang of the first few corners, he changed the training to instead prioritize the lowest time taken to traverse each of the checkpoints along the track.
Terry Pratchett once wrote, “In ancient times cats were worshipped as gods; they have not forgotten this”. [Jonathan]’s cat has clearly not forgotten, and makes it loudly known whenever her favorite chair needs to be moved to stay in the spot of sunlight. He was looking for a fun hack anyway, so he decided to give in to her majesty’s demands, and automated the task.
[Jonathan] first considered adding motorizing the chair itself, but decided to keep it simple and just drag the chair across the room with a spool attached to a motor. The rope spool was attached to a small geared DC motor, mounted on a salad bowl base, and connected to an ESP8266 via a motor driver. The ‘8266 is running NodeMCU with a web server that accepts simple motor commands through a RESTful API. This setup can’t reset the chair to it’s starting position at the end of the day, but this is a small price to pay for simplicity. The motor was a bit underpowered, but it only needed to move the chair in small distances at a time, so [Jonathan] removed the chair’s back to reduce the weight, and upped the motor voltage.
Determining when and how far to move the chair is the second part of the challenge. [Jonathan] considered a simple lookup table for the time of day, but the motor’s movement wasn’t consistent enough. The final solution was a set of three BH1750 digital ambient light sensors to give feedback. A pair of sensors on the chair determines its position relative to the sunny spot, by comparing light levels to a reference sensor mounted in the window. These light sensors are also attached to NodeMCUs, and send movement commands to the winding unit as necessary.
Unfortunately, it appears the hack was in vain, due to the end-user being frightened off by the motor noise. However, it still helped [Jonathan] to scratch his hacking itch, and fortunately for us, he documented the adventure and shared all the code.
This is the first cat chair we covered, but we have seen a few hacks to feed them or keep them away.
It’s a little known secret that when the Hackaday writers gather in their secret underground bunker to work on our plans for world domination, we often take breaks to play our version of the corporate “Buzzword Bingo”, where paradigms are leveraged and meetings circle back to loop in offline stakeholders, or something like that. Our version, however, is “Comment Line Bingo”, and right in the middle of the card is the seemingly most common comment of all: “You should have used a 555,” or variations thereof.
So it was with vicious glee that we came across the Trollduino V1.0 by the deliciously named [Mild Lee Interested]. It’s the hardware answer to the common complaint, which we’ll grant is often justified. The beautiful part of this is that Trollduino occupies the same footprint as an Arduino Uno and is even pin-compatible with the microcontroller board, or at least sort of. The familiar line of components and connectors sprout from the left edge of the board, and headers for shields line the top and bottom edges too. “Sketches” are implemented in hardware, with jumpers and resistors and capacitors of various values plugged in to achieve all the marvelous configurations the indispensable timer chip can be used for. And extra points for the deliberately provocative use of Comic Sans in the silkscreen.
The design intelligently makes use of PCBs to form the entire structure of the glasses. One PCB makes up the left arm of the glasses, carrying an ESP12F microcontroller and the requisite support circuitry. It’s fitted to the front PCB through a slot, and soldered in place. The V+, GND, and DATA connections for the WS2812B LEDs also serve as the mechanical connection. The right arm of the glasses is held on in the same way, being the same as the left arm PCB but simply left unpopulated. A little glue is also used to stiffen up the connection.
There are many schools of thought when it comes to keeping vinyl records clean. It’s a ritual that’s nearly as important as the one that comes after it — queuing up the record and lowering the needle. We’ve seen people use everything from Windex and microfiber towels to ultrasonic cleaning machines that cost hundreds or even thousands. In the midst of building a beefier ultrasonic record cleaner and waiting for parts, [Baserolokus] looked around at all the LEGO around the house and decided to build a plastic prototype in the interim.
The idea behind ultrasonic cleaning is simple — high-frequency sound waves pumped through distilled water produce tons of tiny bubbles. These bubbles gently knock all the dirt and grime out of the grooves without using any brushes, rags, or harsh cleaners. [Baserolokus] built two pieces that hang on the edge of a washtub. On one side, a Technic motor spins the record at just under one RPM, it spins against a 3D printer wheel embedded in the other side. Check it out in action after the break.
Fused Deposition Modelling (FDM) 3D printers which squirt out molten plastic layer by layer are by far the most popular type in general use. Most machines extrude plastic through a nozzle above print bed, and struggle to produce parts with overhangs without using support material. However, a German team of researchers have recently come up with a solution.
In a prototype built by researchers at the Zurich University of Applied Sciences (ZHAW), a standard Cartesian printer has a third rotary axis added, upon which the nozzle can rotate. Additionally, the nozzle is angled at 45 degrees to the print bed, rather than the usual perpendicular setup. This allows layers of a print to be built up in such a way that support material is not needed for the vast majority of typical overhangs. This is particularly useful for hollow parts, where removing support material can be particularly difficult.
The team believes that such technology could be implemented on existing printers by way of a simple upgrade kit, and we can imagine a few experimenters will be champing at the bit to try it out. If you do, be sure to drop us a line. Alternatively, consider using a marker to make removing supports easier. Video after the break.
The basics of digital logic are pretty easy to master, and figuring out how the ones and zeroes flow through various kinds of gates is often an interesting exercise. Taking things down a level and breaking the component AND, OR, and NOR gates down to their underlying analog circuits adds some complexity, but the flow of electrons is still pretty understandable. Substitute all that for photons, though, and you’ll enter a strange world indeed.
At least that’s our take on [Jeroen Vleggaar]’s latest project, which is making logic gates from purely optical components. As he himself admits in the video below, this isn’t exactly unexplored territory, but his method, which uses constructive and destructive interference, seems not to have been used before. The basic “circuit” consists of a generator, a pair of diffraction patterns etched into a quartz plate, and an evaluator, which is basically a pinhole in another plate positioned to coincide with the common focal point of the generator patterns. An OR gate is formed when the two generators are hit with in-phase monochromatic light. Making the two inputs out of phase by 180° results in an XOR gate, as destructive interference between the two inputs prevents any light from making it out of the evaluator.
All seven basic gates are possible using variations of this technique, but of course, actually building such things poses challenges. The microscopic manufacturing techniques, including photolithography and etching patterns on thin metal coatings, are pretty non-trivial. And while [Jeroen] was able to construct a few basic gates and test them, there’s still a long way to go. He says that he needs to add both input beam controls — LCD shutters, perhaps — as well as output detection.
The potential applications of this are pretty exciting, and we’ll be staying tuned for details. For deeper background on the dual nature of light and how interference patterns form, check out [Jeroen]’s explanation of the double-slit experiment.
USB-C Power Delivery 3.0 (PD3.0) introduces a new Programmable Power Supply (PPS) mode, which allows a device to negotiate any supply of 3.3-21 V in 20 mV steps, and up to 5 A of current in 50 mA steps. To make use of this new standard, [Ryan Ma] create the PD Micro, an Arduino-compatible development board, and a self-contained software library to allow easy integration of PD3.0 and the older PD2.0 into projects.
The dev board is built around an ATMega32U4 microcontroller and FUSB302 USB-C PHY. The four-layer PCB is densely packed on both sides to fit in the Arduino Pro Micro Form factor. The board can deliver up to 100W (20 V at 5 A) from an appropriate power source and shows visual feedback on the PD status through a set of LEDs.
The primary goal of the project is actually in the software. [Ryan] found that existing software libraries for PD take up a lot of memory, and are difficult to integrate into small projects. Working from the PD specifications and PD PHY chip data sheet, he created a lighter weight and self-contained software library which consumes less than 8 K of flash and 1 K of RAM. This is less than half the Flash and RAM available on the ATmega32U4.
[Ryan] is running a Crowd Supply campaign (video after the break) to get some of these powerful boards out in the wild, and has released all the source code and schematics on GitHub. The PCB design files will be released during the last week of the campaign, around 25 January 2021.
Considering one of the biggest draws of the original Etch a Sketch was how simple it was, it’s always interesting to see the incredible lengths folks will go to recreate that low-tech experience with modern hardware. A perfect example is this giant wall mounted rendition of the iconic art toy created by [Ben Bernstein]. With a Raspberry Pi and some custom electronics onboard, it can even do its own drawing while you sit back and watch.
At a high level, what we’re seeing here is a standard Samsung LCD TV with a 3D printed Etch a Sketch shell mounted on top of it. That alone would be a pretty neat project, and had [Ben] just thrown some videos of designs getting sketched out onto the display, he could have achieved a similar end result with a lot less work. But where’s the fun in that?
It took hundreds of hours to print the shell.
To make his jumbo Etch a Sketch functional, [Ben] spent more than a year developing the hardware and software necessary to read the user input from the two large 3D printed knobs mounted under the TV. The knobs are connected to stepper motors with custom PCBs mounted to their backs that hold a A4988 driver chip as well as a AS5600 absolute magnetic rotary encoder. This solution allows the Raspberry Pi to not only read the rotation of the knobs when a person is using the Etch a Sketch interactively, but spin them realistically when the software takes over and starts doing an autonomous drawing.
Several Python scripts pull all the various pieces of hardware together and produce the final user interface. The software [Ben] wrote can take an image and generate paths that the Etch a Sketch can use to realistically draw it. The points that the line is to pass through, as well as variables that control knob rotation and pointer speed, are saved into a JSON file so they can easily be loaded later. Towards the end of the Imgur gallery [Ben] has created for this project, you can see the software working its way through a few example sketches.
We’ve seen several projects that motorize an Etch a Sketch to draw complex images, but this may be the first example we’ve seen where everything was done in software. This digital version doesn’t need to follow the traditional “rules”, but we appreciate that [Ben] stuck to them anyway. Incidentally this isn’t the first Etch a Sketch TV conversion to grace these pages, though to be fair, the other project took a radically different approach.
Considering one of the biggest draws of the original Etch a Sketch was how simple it was, it’s always interesting to see the incredible lengths folks will go to recreate that low-tech experience with modern hardware. A perfect example is this giant wall mounted rendition of the iconic art toy created by [Ben Bernstein]. With a Raspberry Pi and some custom electronics onboard, it can even do its own drawing while you sit back and watch.
At a high level, what we’re seeing here is a standard Samsung LCD TV with a 3D printed Etch a Sketch shell mounted on top of it. That alone would be a pretty neat project, and had [Ben] just thrown some videos of designs getting sketched out onto the display, he could have achieved a similar end result with a lot less work. But where’s the fun in that?
It took hundreds of hours to print the shell.
To make his jumbo Etch a Sketch functional, [Ben] spent more than a year developing the hardware and software necessary to read the user input from the two large 3D printed knobs mounted under the TV. The knobs are connected to stepper motors with custom PCBs mounted to their backs that hold a A4988 driver chip as well as a AS5600 absolute magnetic rotary encoder. This solution allows the Raspberry Pi to not only read the rotation of the knobs when a person is using the Etch a Sketch interactively, but spin them realistically when the software takes over and starts doing an autonomous drawing.
Several Python scripts pull all the various pieces of hardware together and produce the final user interface. The software [Ben] wrote can take an image and generate paths that the Etch a Sketch can use to realistically draw it. The points that the line is to pass through, as well as variables that control knob rotation and pointer speed, are saved into a JSON file so they can easily be loaded later. Towards the end of the Imgur gallery [Ben] has created for this project, you can see the software working its way through a few example sketches.
We’ve seen several projects that motorize an Etch a Sketch to draw complex images, but this may be the first example we’ve seen where everything was done in software. This digital version doesn’t need to follow the traditional “rules”, but we appreciate that [Ben] stuck to them anyway. Incidentally this isn’t the first Etch a Sketch TV conversion to grace these pages, though to be fair, the other project took a radically different approach.
Software defined radio lets RF hardware take on a broad spectrum of tasks, all based on how that hardware is utilized in code. The bladeRF 2.0 micro xA9 is one such device, packing a fat FPGA with plenty of room for signal processing chains on board. As a demonstration of its abilities, [Robert Ghilduta] set about writing a software-defined WiFi implementation for the platform.
The work is known as bladeRF-wiphy, as it implements the PHY, or physical layer of the WiFi connection, in the 7-layer OSI networking model. Modulation and demodulation of the WiFi signal is all handled onboard the Cyclone V FPGA, with the decoded 802.11 WiFI packets handed over to the Linux mac80211 module which handles the MAC level, or medium access control. Thanks to the capability baked into mac80211, the system can act as either an access point or an individual station depending on the task at hand.
[Robert] does a great job of explaining the why and the how of implementing WiFi modulation on an FPGA, as well as some basics of modem development in both software and hardware. It’s dense stuff, so for those new to the field of software defined radio, consider taking some classes to get yourself up to speed!
Back in the 20th century, Lego Technic was a popular toy designed to teach kids about mechanical technology, and be a lot of fun to boot. Motors and pneumatics were available, but by and large you had to move your creations and make the noises yourself. That’s not the case these days, as the [Brick Experiment Channel] demonstrates with this impressive Lego tank.
The drivetrain is straightforward, using standard Lego tank treads with each side given its own motor for easy skid steering. However, the real party piece is the slingshot cannon, which launches Lego soccer balls at 60 km/h. Utilizing several motors, it’s complete with elevation adjustment for accurate ranging, and a 6 round magazine so you can (slowly) prosecute your targets with rounds downrange.
What really makes this build great is the control system, with the tank being controlled by a PS4 controller via Sbrick, a device that lets Lego motors be controlled via Bluetooth. We’d love to build a couple of Lego vehicles and have them blast away at each other. We’ve seen the technology used before for a secret heist robot. Video after the break.
If there’s anything about amateur radio that has more witchcraft in it than the design and implementation of antennas, we don’t know what it would be. On the face of it, hanging out a chunk of wire doesn’t seem like it should be complicated, but when you dive into the details, building effective antennas and matching them to the job at hand can be pretty complex.
That doesn’t mean antenna topics have to remain a total mystery, of course, especially once someone takes the time to explain things properly. [Charlie Morris (ZL2CTM)] recently did this with a simple antenna tuner, a device used to match impedances between a transmitter and an antenna. As he explains in the first video below, his tuner design is really just a Wheatstone bridge where the antenna forms half of one leg. A toroidal transformer with multiple taps and a variable capacitor forms an LC circuit that matches the high impedance antenna, in this case a multi-band end-fed halfwave, with the nominal 50-ohm load expected by the transceiver. A small meter and a diode detector indicate when the bridge is balanced, which means the transceiver is seeing the proper load.
The second video below shows the final implementation of the tuner; as a fan of QRP, or low-power operation, [Charlie] favors simple, lightweight homebrew gear that can be easily taken into the field, and this certainly fits the bill. A final video shows the tuner in use in the field, with a NanoVNA proving what it can do. As usual, [Charlie] protests that he not an expert and that he’s just documenting what he did, but he always does such a good job of presenting the calculations involved in component selection that any ham should be able to replicate his builds.
