Share Screen To RGB Panel With Pi Pico W

August 28, 2022 by Danie Conradie 13 Comments

RGB LEDs are great for adding a bit of color to your life, and it’s even more satisfying to use a matrix of them as a graphic display. [bitluni] built an RGB LED display with Pi Pico to which you can share a pixelated version of your PC’s screen.

[bitluni] wanted to gain some experience with MicroPython on the Raspbery Pi Pico W, and had previously used WebSockets to transmit display data over WiFi. Unfortunately, the available MicroPython WebSockets implementation didn’t leave enough RAM for the rest of the code. Instead, he set up a simple HTTP server on the Pico that receives the pixel data as a POST request. This makes for a slow refresh rate but still looks great, especially with the 3D printed rear-projection frame.

To send display data from the computer, [bitluni] uses a simple locally hosted HTML page that takes the Pico’s IP address, and prompts you to select the display or window you want to share. It uses JavaScript to grab the display data, generate the required low-res pixel values, and send the POST request.

This looks like a fun weekend project to add to your lab or home and only costs about $20 in parts. It’s basically a scaled-down version of his giant ping pong ball wall display.

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Hackaday Prize 2022: Compact Solar Tracking System Doesn’t Break The Bank

August 28, 2022 by Danie Conradie 33 Comments

If you need to squeeze every available watt out of a solar panel, you’ll probably want to look into a solar tracking system. Unfortunately, they are usually quite large, heavy, and expensive. As an alternative, [JP Gleyzes] has put together a DIY solar tracking system that aims to address these issues.

Starting with a 100 W flexible solar panel purchased during a Black Friday sale, [JP] first created a simple frame using 20 mm PVC tubing and a few 3D printed brackets. It mounts on a wooden base with a printed worm gear rotation mechanism, powered by a stepper motor. The tilt is a handled by a lead screw made from a threaded rod, connected between the wooden base and the top of the solar panel, and is also driven by a stepper motor.

For even more efficiency, [JP] also created an MPPT charge controller with companion app using an ESP32, modified 20 A buck converter, and current sensor module. The ESP32 also controls the stepper motors. The optimum angle for the solar panel determined using the date, time, and the system’s GPS position. [JP] had also created a simple Android app to calibrate the panels’ start position.

This project is a finalist in the Planet-Friendly Power challenge of the 2022 Hackaday Prize, and all the details to build your own are available on your project page. Looking at the size of the system, we suspect future iterations could be even smaller.

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High Speed RC Jet Car Is A Harsh Teacher

August 28, 2022 by Danie Conradie 8 Comments

Making machines go fast has always been a seemingly unavoidable impulse for humans. With the advent of radio control, it’s possible to get a taste of the rush without putting your life and too much money on the line. In the spirit of speed, [James Whomsley] strapped a jet turbine engine to an RC car, and learned some hard lessons along the way.

The car started as a four-wheel drive electric race car, but [James] removed most of the drive train components and mounted the jet turbine engine on a pair of 3D printed struts. Originally intended for large-scale RC planes, the little jet engine produces about 120 N of thrust. To allow the car to stop, [James] kept the drive shafts and connected them to a centrally mounted disk brake unit.

For the first high-speed test runs, James added a vacuum-formed shell and a pair of large vertical stabilizers for high-speed stability. On the 3rd test run at a local racetrack, the car got up to 190 km/h (118 MPH) before it veered off the track and crashed. Fortunately, the chassis and engine only sustained minor damage and were easy to repair.

James rebuilt the car with a lower engine to reduce the center of gravity and added an electronic gyro in an attempt to stabilize the car at high speed. Time ran out, and he wasn’t able to test the car before taking it to a high-speed RC event held on a runway. This led to another crash when the car again veered off the track after badly oscillating. After checking the onboard footage, [James] discovered the receiver had experienced a loss of signal, and an incorrect fail-safe setting made the engine go full throttle. After more tests, James also found that excessive play in the steering mechanism had caused the gyro to induce oscillations.

Although this car failed in the end, [James] intends to take the lessons learned into a new high-speed car build. [rctestflight] also did some testing with an EDF-powered RC car recently, and used a drone flight controller for high speed stability. This is not [James]’ first foray into speed machines, having previously experimented with a rocket plane.

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DIY Video Transmitter Turned WiFi Jammer

August 27, 2022 by Danie Conradie 31 Comments

The proliferation of FPV drones has brought a flood of cheap wireless video tech. After flying and crashing a cheap FPV drone for a bit, [GreatScott] decided to try his hand at building his own video transmitter, which turned out to be a lot harder than expected.

While digital technology has caught up to the FPV world, a lot of systems still use analog video, especially for drone racing. The video quality isn’t great, but it has the advantage of very low latency. The technology is very similar to the old analog TV broadcasts, but mainly uses the 5.8 GHz license-free bands. It is essentially analog video signal, frequency modulated onto a 5.8 GHz carrier signal transmitted through an appropriately sized antenna.

After a brief failed experiment with a simple circuit built from discrete components, [GreatScott] turned his attention to voltage-controlled oscillators (VCO). He bought a couple of 5.8 GHz VCOs from Aliexpress, and created and used a simple opamp circuit to boost the FPV camera video signal to the required input level for the VCO. This failed to produce any identifiable image on his video receiver goggles. In an attempt to confirm that the VCOs produced the desired frequency, he ordered a similar 2.4 GHz VCOs and built a short range (20 cm) WiFi jammer. With a signal generator to create a simple input signal, and confirmed that it interfered with his laptop’s WiFi connection.

After more experimentation with other VCOs, the closest [GreatScott] came to success was a barely identifiable image transmitted using a Maxim 2.4 GHz VCO. If you have any ideas on what is missing in the VTX circuit, drop them in the comments below.

Building RF circuits that interfere with the legitimate signal around you, or broadcasting out of band, is generally not a great idea, and could earn you an unpleasant visit from the authorities. If you want to build your own digital video transmission, take a look at the Wifibroadcast project.

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Make Your Own Vinegar

August 26, 2022 by Danie Conradie 32 Comments

Making fermentation work for us is one of the original hacks that allowed humans to make food last longer, and festivities more interesting. [Mike G] has been experimenting with making his own vinegar, and found the end product to be a delicious addition to his cooking.

The first step is similar to making alcoholic beverages. Take something that contains sugar, like fruit, mix it with water and let stand. Wild yeast will feed on the sugar and create alcohol. Once the alcohol content reaches the 6-12% range, the resulting liquid can be separated from the solids and left exposed to the air. This allows Acetobacter bacteria to convert the alcohol into acetic acid, producing vinegar. The entire process takes around 30 days.

[Mike]’s first round of experiments was mainly with fresh fruit, with the addition of raisins. To prevent white mold from forming the mixtures should be stirred daily, but life got in the way and mold got out of control on all the fruits, except for the raisins. This gave [Mike] the to try another round with dried fruit, which was significantly less prone to mold, and produced deliciously flavored vinegar. [Mike] also demonstrated their use in a couple of mouth-watering dishes.

The DIY vinegar production process is just begging for some fermentation monitoring and automation tech. We’ve seen plenty of sourdough and beer production projects, which we suspect could also be applied to vinegar production with some minor changes.

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Water Monitor Measures The Cost Of Your Shower Thinking Time

August 26, 2022 by Danie Conradie 18 Comments

The shower is one of the top thinking places for many of us, but can get a bit out of hand with water wastage and utility bills if you go down a deep rabbit hole. To be more mindful of his water usage in the shower, [GreatScott!] created a power sipping water monitor that lives there.

The device is built around a cheap 1/2″ brass water flow rate sensor connected to his shower hose, which outputs pulses as a small wheel passes an internal hall effect sensor. The datasheet didn’t contain any spec for pulses/volume, so [GreatScott!] had to experimentally determine this by filling a one-liter container with water and counting the pulses. He found that the pulse count per liter was dependent on the flow rate, so he narrowed down the variables and just determined the average count at his shower’s pressure and flow rate.

The sensor is connected to a battery-powered ESP8266 housed inside a sealed 3D-printed enclosure in the shower. To reduce power usage to a minimum, a flow switch was added in series with the flow meter, which only switches on the ESP8266 when water starts flowing. A latching circuit keeps the ESP powered after the water stops, giving it enough time to transmit the data before shutting down. This type of circuit is very handy for any battery-powered project connected to an external switch or sensor.

It is programmed with ESPHome and outputs the data to a local Home Assistant server, so no data is saved on someone else’s server.

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A Guide To 3D Printing Model Aircraft Wings

August 26, 2022 by Danie Conradie 32 Comments

The exact airfoil shape of a wing has a massive effect on the performance and efficiency of an aircraft and will be selected based on the intended flight envelope. If you’re moving beyond foam board wings, 3D printing is an excellent way to create an accurate airfoil, and [Tom Stanton] provides us with an excellent guide to modeling wing sections for easy printing.

[Tom] used the process demonstrated in the video after the break to create the wing for his latest VTOL RC aircraft. It was printed with lightweight PLA, which can ooze badly when it stops extruding. To get around this, he designed the wings and their internal ribs to be printed in one continuously extruded line.

He wanted a wing that would allow a smooth transition from hover to forward flight, and used the Airfoil Tools website to find and download the appropriate airfoil profile. After importing the profile into Fusion 360, he created internal ribs in a diagonal grid pattern, with lightening holes running along the length of the wing. A cylinder runs along the core of the wing to fit a carbon fiber wing spar. The ribs are first treated as a separate body in CAD and split into four quadrants. When these quadrants combine with the outer shell, it allows the slicer to treat the entire print as a continuous external perimeter line using “vase mode“.

These steps might seem simple, but it took about 3 weeks of experimentation to find a process that works. It’s primarily intended for straight wings with a continuous profile, but it should be adaptable to tapered/swept wings too. A well-designed airframe is essential when pushing aircraft to the edge of efficiency, like solar-powered plane to fly overnight.

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