Author: Al Williams

4508 Articles

Earthquake Detection On A Chip

July 6, 2019 by 14 Comments

If you’ve ever been in an earthquake you’d assume it would be pretty easy to detect one. If things are shaking, there’s an earthquake. In reality, though, a lot of things can shake a sensitive instrument that is detecting shaking, so — for example — mechanical sensors will produce a lot of false positives. Now, however, you can filter out errant vibrations and reliably detect earthquakes on a chip.

The Rohm BP3901 has two primary features. First, it supposedly eliminates false detections due to things like a heavy truck rumbling by. In addition, while most sensors must be mounted completely flat, the BP3901 has a compensation method for angle which lets you mount it as much as 15 degrees rotated in either direction and still get good results. That’s because the BP3901 is based on the combination of an accelerometer and a microcontroller in one package to detect movement, characterize it based on an algorithm and reacting through an I2C bus and an INT pin.

Rohm suggests you could power the BP3901 for about 5 years with two AA batteries with the example of averaging 10 three-minute wake up events a month. We aren’t sure why we want to detect an earthquake, but we think we do. Imagine a large sensor network sending back real-time data as an earthquake happens — something we saw last year using Raspberry Pi. That project used a Geophone as the detector, which could be replaced by this chip. Rohm plans to have “OEM quantities” for sale next month which we hope means we can get smaller quantities from distributors.

A lot of people spend a lot of time thinking about how to predict earthquakes, as we’ve seen before. Of interest, the ancient Romans may have had a way to deflect earthquakes, so they probably didn’t care as much about detecting them.

The Power Of Directional Antennas

July 3, 2019 by 32 Comments

AM broadcasting had a big problem, but usually only at night. During the day the AM signals had limited range, but at night they could travel across the country. With simple wire antennas, any two stations on the same frequency would interfere with each other. Because of this, the FCC required most radio stations to shut down or reduce power at night leaving just a handful of “clear channel” stations for nighttime programming. However, creating directional antennas allowed more stations to share channels and that’s the subject of a recent post by [John Schneider].

When it comes to antennas, ham radio operators often think bigger is better. After all, hams typically want to work stations far away, not some specific location. That’s not true in the commercial world, though. The big breakthrough that led to, for example, cell phones was the realization that making smaller antennas with lower power at higher frequencies would allow for reuse of channels. In those areas the focus is on making cells smaller and smaller to accommodate more people. You can think of AM broadcasting as using the same idea, except with relatively large cells.

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Spice With A Sound Card

July 3, 2019 by 11 Comments

In years gone by, trying out a new circuit probably would have meant heating up a soldering iron. Solderless breadboards have made that even easier and computer simulation is easier still, but there’s something not quite as satisfying about building a circuit virtually. [Thedeuluiz] has a way to get some of the best of both worlds with the RTSpice project.

The idea is simple in concept, although not as simple in execution. The program does a Spice-like simulation of a circuit and can accept input and produce output from a PC’s sound card. Obviously, that means you can’t simulate RF circuits — at least not at the input and the output. It also means the simulation has to run lightning fast to keep up with the sound card sample rate. According to the author, it works best with modest circuits but exactly how big you can go will depend on your hardware.

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Locking Up Lock Washers

July 3, 2019 by 41 Comments

We’ll admit most of us are more comfortable with solder and software than mechanical things. However, between robots, 3D printers, and various other mechanical devices, we sometimes have to dig into springs, belleville washers, and linear actuators. Unless you are a mechanical engineer, you might not realize there’s a lot of nuances to something even as simple as a nut and bolt. How many threads do you need to engage? Do lock washers work? [Engineer Dog] has a post that answers these and many other questions.

The top ten list starts off with something controversial: split ring lock washers don’t work. The original post cites a paper that claims they don’t except in very special circumstances. However, he updated the post later to say that some people disagree with his cited study. In the end, you’ll have to decide, but given there are other options, maybe we’ll start using those more often.

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Ask Hackaday: How Can You Build For A Ten Millennia Lifespan?

July 1, 2019 by 97 Comments

There’s been a lot of news lately about the Long Now Foundation and Jeff Bezos spending $42 million or so on a giant mechanical clock that is supposed to run for 10,000 years. We aren’t sure we really agree that it is truly a 10,000 year clock because it draws energy — in part — from people visiting it. As far as we can tell, inventor Danny Hills has made the clock to hoard energy from several sources and occasionally chime when it has enough energy, so we aren’t sure how it truly sustains itself. However, it did lead us to an interesting question: how could you design something that really worked for 10,000 years?

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Scripting Language Rapidly Develops A Clock

June 27, 2019 by 17 Comments

In the past, you might very well have started programming in Basic. It wasn’t very powerful language and it was difficult to build big projects with, but it was simple to learn, easy to use, and the interpreter made it easy to try things out without a big investment of time. Today you are more likely to get started using something like an Arduino, but it is easy to miss the accessible language and immediate feedback when you are doing simple projects. Annex WiFi RDS (Rapid Development Suite) is a scripting language for the ESP8266 that isn’t quite Basic, but it shares a lot of the same attributes. One example project from [cicciocb] is a scrolling dot matrix LED clock.

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Smart Bike Helmet Is Wireless

June 26, 2019 by 16 Comments

If you ride a bike, you probably share the road with a lot of cars. Unfortunately, they don’t always share the road very well with you. [Mech Tools] took a helmet, a few Arduinos, and some wireless transceivers and made headgear that shows when you stop and also shows turn signals. We were a little surprised, though, that the bike in question looks like a motorcycle. In most countries, motorcycle helmets meet strict safety standards and modifying them is probably not a good idea. However, it wasn’t exactly clear how the extra gear attached to the helmet, so it is hard to say if the project is very practical or not.

In particular, it looks as though the first version had the electronics just stuck to the outside of the helmet. The final one had things mounted internally and almost certainly had cuts or holes made for the lights. We aren’t sure which of those would be more likely to be a problem in the case of an accident.

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