Careful Cuts Lets Logger Last A Year On A Coin Cell

March 14, 2022 by Bryan Cockfield 21 Comments

Coin cells are great for backup power for things like real-time clocks, or even for powering incredibly small mechanical devices like watches. But for something like a data logger, running on a standard microcontroller, most people would reach for a lithium cell of some sort. Not so with this build, though, which squeezes every joule of energy from a coin cell in order to run a data logger for a full year.

Most of the design and engineering required to improve the efficiency of the data logger involve standard practices for low-power devices such as shutting off unnecessary components and putting the device to sleep when not actively running, but this build goes far beyond that. The Vcc pin on the RTC was clipped which disables some of its internal logic but still keeps its basic functionality intact.

All of the voltage regulators were removed or disabled in favor of custom circuitry that doesn’t waste as much energy. The status and power LEDs were removed where possible, and the entire data logger is equipped with custom energy-efficient code as well.

If you’re starting a low-power project, even one that isn’t a datalogger, it’s worth checking out this build to see just how far you can go if you’re willing to hack at a PCB with cutting tools and a soldering iron. As to why this data logger needed such a low power requirement, it turns out it’s part of a kit being used in classrooms and using a coin cell brought the price of the entire unit down tremendously. Even if you have lithium cells on hand, though, it’s still worthwhile to check out the low power modes of your microcontroller.

Thanks to [Adrian] for the tip!

Longer Range EVs Are On The Horizon

January 19, 2022 by Lewin Day 165 Comments

When electric cars first started hitting the mainstream just over a decade ago, most criticism focused on the limited range available and the long recharge times required. Since then, automakers have been chipping away, improving efficiency here and adding capacity there, slowly pushing the numbers up year after year.

Models are now on the market offering in excess of 400 miles between charges, but lurking on the horizon are cars with ever-greater range. The technology stands at a tipping point where a electric car will easily be able to go further on a charge than the average driver can reasonably drive in a day. Let’s explore what’s just around the corner.

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DIY Relay Module Saves Time

September 6, 2020 by Bryan Cockfield 22 Comments

As any programmer could tell you, there’s significant value in automating a process that is performed often enough. The more times that process is used, the more it makes sense to automate it or at least improve its efficiency. This rule isn’t limited to software though; improvements to hardware design can also see improvements in efficiency as well. For that reason, [Hulk] designed a simple relay module in order to cut the amount of time he spends implementing this solution in his various other projects.

While driving a relay with a transistor is something fundamental, this project isn’t really about that per se. It’s about recognizing something that you do too much, and then designing that drudgery out of your projects. [Hulk] was able to design a PCB with 12 modules on it, presumably saving fabrication costs. He can then easily populate them with specific components as soon as he needs one. Another benefit of designing something like this yourself, rather than an off-the-shelf relay module, is that you can do away with any useless features you’ll never need (or add ones that aren’t available in commercial devices).

We can appreciate the efficiency gains this would make for our next project that needs a simple driver for a light, garage door opener, or any other binary electronic device. It can be a hassle to go find the correct transistor and relay, solder it all on the project board, and hope it all works. A pre-made solution solves all these issues, but we do wish the schematics were available to keep us from having to design our own. Driver boards are a pretty common project for all the different types of relays we see around here, so there is probably one available out there.

An Open Source Ebike

February 23, 2020 by Bryan Cockfield 47 Comments

In the ebike world, there are two paths. The first is a homemade kit bike with motors and controllers from China. The second is a prebuilt bike from a manufacturer like Giant, with motors and controllers from China, which will be half as fast and cost three times as much. The choice is obvious, and there are other benefits to taking the first path as well, such as using this equipment which now has an open source firmware option.

The Tong Sheng TSDZ2 drive is popular in the ebike world because it’s an affordable kit motor which has a pedal-assist mode using torque sensors, resulting in a more polished experience. In contrast, other popular kit motors tend to rely on less expensive cadence sensors which are not as smooth or intuitive. This new open source firmware for the TSDZ2 further improves on the ride by improving the motor responsiveness, improving battery efficiency, and opening up the ability to use any of a number of color displays. (More information is available on a separate Wiki.)

If you have a TSDZ2-based ebike it might be time to break out the laptop and get to work installing this firmware. If you’re behind the times and still haven’t figured out that ebikes are one of the best ways to travel, here is the proof you need.

Thanks to [coaxial] for the tip! Photo via Reddit user [PippyLongSausage].

How Efficient Can An Airplane Be? The Celera 500L Sets To Find Out

January 22, 2020 by Roger Cheng 83 Comments

One of the current hype trends is the supposedly imminent revolution in air transport. So many companies showing digital renderings and mockups to illustrate their own utopic vision for the future, reaching fevered pitch at events like CES 2020. But aviation has a long history of machinery that turned out to be impractical. Wouldn’t it be great if a company focused their resources on building real aircraft and get real data before cranking up their hype machine? The people at Otto Aviation thought so, and their Celera 500L has reportedly taken to the skies.

If you said “Otto who?” you are not alone. The company has zero PR activity to speak of. Limited internet attention started from aviation fans spotting the Celera 500L under construction at its Southern California airfield. Its unusual exterior appearance and proximity to Hollywood made some dismiss it at first as a movie prop. Anyone with a passing interest in aerospace engineering could immediately see aerodynamics was a priority in this design, its long thin unswept glider-like wings implies the goal is fuel efficiency rather than speed. This was confirmed by internet sleuths uncovering patents filed by people associated with the company.

The patents include very lofty fuel efficiency goals, and industry veterans are skeptical. Fuel is a huge factor in aircraft operating costs where small increases in efficiency translate to big dollars over a plane’s lifetime. It’s hard to believe every other plane maker would deliberately leave so much on the table. There must be far more to the 500L inside that teardrop shaped body, with innovations and potentially making some trade-offs no other company has made. We can see two of them from the outside: the 500L traded off some pilot visibility for aerodynamics, and it has very little ground clearance to absorb the impact of less-than-ideal landings.

It’s certainly possible the ideas leading to this plane will fail to pan out in reality like so many ideas before them. Aerospace engineering is a field littered with debris of concepts that looked great on paper but crashed against a hard and unforgiving reality. But at least Otto Aviation is trying something new by building real hardware to get real data, something well worth recognizing in a sea of hyped up fantasy renderings.

[Photo via SoCal Airshow Review]

Where The Work Is Really Done – Casual Profiling

July 29, 2019 by Bryan Cockfield 13 Comments

Once a program has been debugged and works properly, it might be time to start optimizing it. A common way of doing this is a method called profiling – watching a program execute and counting the amount of computing time each step in the program takes. This is all well and good for most programs, but gets complicated when processes execute on more than one core. A profiler may count time spent waiting in a program for a process in another core to finish, giving meaningless results. To solve this problem, a method called casual profiling was developed.

In casual profiling, markers are placed in the code and the profiler can measure how fast the program gets to these markers. Since multiple cores are involved, and the profiler can’t speed up the rest of the program, it actually slows everything else down and measures the markers in order to simulate an increase in speed. [Daniel Morsig] took this idea and implemented it in Go, with an example used to demonstrate its effectiveness speeding up a single process by 95%, resulting in a 22% increase in the entire program. Using a regular profiler only counted a 3% increase, which was not as informative as the casual profiler’s 22% measurement.

We got this tip from [Greg Kennedy] who notes that he hasn’t seen much use of casual profiling outside of the academic world, but we agree that there is likely some usefulness to this method of keeping track of a multi-threaded program’s efficiency. If you know of any other ways of solving this problem, or have seen causal profiling in use in the wild, let us know in the comments below.

Header image: Alan Lorenzo [CC BY-SA 3.0].

Tech Imitates Life: Fireflies Make Better Light Bulbs

March 5, 2019 by Al Williams 46 Comments

While we often think we are clever designers, living things often meet or beat the best human designs. It is easy to forget that nature even has living lightbulbs, among them the firefly. Researchers from Penn State decided to compare how fireflies create light and found that they deal with a problem similar to LEDs. The insight may lead to an increase in efficiency for LEDs, which is currently about 50%.

The problem is that some light generated never gets out of the LED (or the firefly’s body). Some light inevitably reflects back into the device. One known mitigation for this is creating a tiny texture pattern on the LED surface which allows more light to escape. These are typically a V-shaped structure etched into the surface. This isn’t news to the firefly, however, which has similar structures on their lanterns as do some other light-generating animals (apparently glowing cockroaches are a thing). However, the organic structures differ from LED textures in an important way.

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