Month: January 2020

Reducing The Risk Of Flying With Hydrogen Fuels

January 1, 2020 by 91 Comments

Flight shaming is the hot new thing where people who take more than a handful of trips on an airplane per year are ridiculed for the environmental impact of their travels. It’s one strategy for making flying more sustainable, but it’s simply not viable for ultimately reducing the carbon impact that the airline industries have on the environment.

Electric planes are an interesting place to look for answers. Though carbon-free long haul travel is possible, it’s not a reality for most situations in which people travel today. Current battery technology can’t get anywhere near the energy density of fossil fuels and larger batteries aren’t an option since every pound matters when designing aircraft.

Even with land travel and electric grids improving in their use of renewables and electric power, aviation tends to be difficult to power with anything other than hydrocarbons. Student engineers in the AeroDelft program in the Netherlands have created Project Phoenix to develop an aircraft powered by a liquid hydrogen fuel cell, producing a primary emission of water vapor. So it is an electric plane, but leverages the energy density of hydrocarbons to get around the battery weight problem.

While the project may seem like an enormous reach peppered with potential safety hazards, redundant safety features are used such as sensors and vents in case of a hydrogen leakage, as well as an electric battery in case of failure. Hydrogen produced three times more energy per unit than kerosene, but is six times the volume in gas form and requires cumbersome compression tanks.

Even though hydrogen fuel only produces water vapor as a byproduct, it can still cause greenhouse effects if it is released too high and creates clouds. The team is exploring storage tanks for slow release of the water vapor at more optimal altitudes. On top of that, most hydrogen is produced using steam methane reforming (SMR), creating up to 150g of greenhouse gases per kWh, and electrolysis tends to be more costly and rarely carbon neutral. Alternatives such as solar power, biofuels, and electric power are looking to make headwind as well, but the technology is still far from perfected.

While it’s difficult to predict the success of the project so early on, the idea of reducing risk in hydrogen fuels may not be limited to a handful of companies for very long.

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Happy 50th Birthday To All You Epoch Birthers

January 1, 2020 by 19 Comments

Good morning everyone, and what a lovely start to the new year it is, because it’s your birthday! Happy birthday, it’s your 50th! What’s that you say, you aren’t 50 today? (Looks…) That’s what all these internet databases say, because you’ve spent the last decade or so putting 1970-01-01 as your birth date into every online form that doesn’t really need to know it!

It’s been a staple for a subset of our community for years, to put the UNIX epoch, January 1st 1970, into web forms as a birth date. There are even rumours that some sites now won’t accept that date as a birthday, such is the volume of false entries they have with that date. It’s worth taking a minute though to consider UNIX time, some of its history and how its storage has changed over the years.

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Magnetic Circuits Are More Attractive Than Breadboarding

January 1, 2020 by 16 Comments

Let’s face it, breadboarding can be frustrating, even for advanced electronics wizards. If you have an older board, you could be dealing with loose tie points left from large component legs, and power rails of questionable continuity. Conversely, it can be hard to jam just-made jumper wires into new boards without crumpling the copper. And no matter what the condition of the board is, once you’ve plugged in more than a few components, the circuit becomes hard to follow, much less troubleshoot when things go pear-shaped.

In the last twenty years or so, we’ve seen systems like Snap Circuits and Little Bits emerge that simplify the circuit building process by making the connections more intuitive and LEGO-like than even those 160-in-1 kits where you shove component legs between the coils of tight little springs. You will pay handsomely for this connective convenience. But why should you? Just make your own circuit blocks with cardboard, magnets, and copper tape. It should only cost about 10ยข each, as long as you source your magnets cheaply.

[rgco] gives the lowdown on building a minimal set of 23 component and connector blocks using 100 magnets. He’s got 11 example circuits to get you started, and some example videos of more advanced circuits that got tacked up after the break.

This method of making the circuit look more like the schematic may be the best way for the visually-inclined to learn electronics. But the best way to learn electronics depends on where you’re coming from.

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Building A Giant Meta-Clock Made Of Smaller Clocks

January 1, 2020 by 18 Comments

Have any last-minute projects you finished just before the end of the decade? To help pass the time, [Erich Styger] decided to build a meta digital clock made up of 24 individual analog clocks, the perfect item to help welcome in the new year. The stepper clock is controlled by a network of LPC microcontrollers, displaying the time and room temperature, as well as several aesthetically pleasing loading animations.

Each clock operates from a 5 V USB power bank drawing less than 2 A for the full 24-clock setup. The meta-clock resides in a laser cut enclosure, with 3D printed hands telling the time. While having one board per clock would be easier to implement, [Erich] decided to use one board per four clocks arranged in rows to save on costs. The arrangement fixes the distance between clocks, though [Erich] also made the clock size slightly smaller to compensate.

The ‘stepper’ part of the stepper clock uses a 360 degree version of the VID28 stepper motor to reduce the height of the design and the cost of the project. Apart from the X12.017 driver silently driving the motors, the stepper motors also conveniently only need a ‘direction’ and ‘step’ pin, reducing the pin count needed for the microcontroller. Neodymium magnets and hall effect sensors are used for tracking the position of the hands as the clocks move, with the magnets embedded into the clock hands.

As for communication, rather than use the common I2C protocol, the more robust RS-485 was selected. A master coordinates all of the clocks using the bus, providing a command line interface. The master is also able to communicate with the host PC over USB to maintain RTC time.

During the software development phase, [Erich] made use of the SEGGER J-Link EDU mini CLI for keeping track of information about the driver and each individual stepper motor. The software controlling the motors is written in C, with boards running FreeRTOS. The stepping is handled with a timer interrupt, but because the LPC845 doesn’t have enough timer channels, all of the functionality is done within a single channel. This results in plenty of interrupt handlers, flags, and callbacks across the code, which makes for some good fun.

Speaking of clocks, check out some of our other past clock hacks, including this mini-VFD clock and this fun LED matrix clock (it lets you play Tetris!)

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