Arduino Analog I/O Multiplexer

June 9, 2018 by Al Williams 15 Comments

[SeanHodgins] has a project in mind where he needs to sample over 500 analog sensors. To get ready, he made a breakout board for 32-channel analog multiplexer device he wants to use. He put the project out on Hackaday.io and also has a video tutorial you can see below.

There are five input pins to the chip which lets you connect one analog pin to any one of 32 analog pins. Of course, in addition to the five control lines, you need some handshaking lines, too so you could use as many as eight digital pins to control the device.

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WiFi Pool Controller Only Cost $20

June 7, 2018 by Al Williams 26 Comments

Pools have come a long way. It used to be you had a pump and if you were lucky it had a mechanical timer switch on it. That was it. Now you have digital controllers and spa jets and heaters. You can even get them that connect to your home automation system. If your pool isn’t new enough to do that already, you can get a range of add-on accessories. For a price. [Rob] paid $500 to get a remote for his pool. It wasn’t even WiFi, just a simple RF remote. In 3 years, the transmitter had burned out ($300 to replace) and he decided he had enough. For $20, [Rob] added MQTT control and monitoring to his pool using an ESP8266. You can see the video description of the project below.

Naturally, the instructions are a bit specific to the Pentair system he has. However, it isn’t as specialized as you might think. The project relies on the connection for a wired “spa-side remote” that most modern pool systems support. The electrical connections for these aren’t quite standard, but they are all very similar, so you have a good chance of reproducing this for your setup assuming you have a connection for one of these wired remotes.

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Roll A Black Box For Your Wheels

June 6, 2018 by Kristina Panos 22 Comments

Telemetric devices for vehicles, better known as black boxes, cracked the consumer scene 25 years ago with the premiere of OnStar. These days, you can get one for free from your insurance company if you want to try your luck at the discounts for safe driving game. But what if you wanted a black box just to mess around with that doesn’t share your driving data with the world? Just make one.

[TheForeignMan]’s DIY telematics box was designed to pull reports of the car’s RPM, speed, and throttle depression angle through the ODBII port. An ODBII-to-Bluetooth module sends the data to an Arduino Mega and logs it on an SD card along with latitude and longitude from a NEO-6M GPS module. Everything is powered by the car’s battery through a cigarette lighter-USB adapter.

He’s got everything tightly wrapped up inside a 3D printed box, which makes it pretty hard to retrieve the SD card. In the future, he’d like to send the data to a server instead to avoid accidentally dislodging a jumper wire.

If this one isn’t DIY enough for you to emulate, start by building your own CAN bus reader.

Teddy Ruxpin: Navigate To 143 Main Street

June 4, 2018 by Al Williams 15 Comments

In the United States, TV and radio stations have to give the opportunity of equal airtime to all candidates. In that spirit, we thought we should show you [Jayden17’s] hack that puts Google Assistant into a Teddy Ruxpin. You can see the hacked bear do its thing in the video below.

Teddy was the best-selling toy for 1985 and 1986, and is still available, so over 30 years there are a lot of these hanging around. If you never looked at how they work, the original ones were quite simple. A cassette player routed one stereo channel to a speaker and used the other channel to control servo motors to move the mouth and eyes. The cassette was eventually replaced with a digital cartridge, and newer versions of Teddy only use two motors instead of the three in the original.

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$6 Weather Station Goes Where You Do

June 3, 2018 by Al Williams 24 Comments

We admit, we see a lot of weather stations. What makes [Mike Diamond’s] take on this old favorite interesting is that it is tiny enough to carry with you, and uses your cell phone as a hotspot to deliver its data. Of course, that assumes you have a phone that can act as a hotspot.

The parts are straightforward, a power supply, an ESP8266, and a weather sensor board. It looks as though you could easily slip the whole affair into a tube or maybe a 3D printed enclosure. We were a little concerned about the bare wire used, but as [Mike] points out you can use insulated wire if you like, and we’d encourage you to do so.

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3D Printed Tank Has Slick Tread Design

June 2, 2018 by Donald Papp 4 Comments

Tank projects are great because while every tank design is the same in a fundamental way, there’s nevertheless endless variety in the execution and results. [Hoo Jian Li]’s 3D Printed Tank is smartly laid out and has an unusual tank tread that shows off some slick curves.

The tank itself is remotely controlled over Bluetooth with a custom controller that uses the common HC-05 Bluetooth radio units. The treads are driven by four hobby gearmotors with custom designed wheels, and run over an idler wheel in the center of the body. There isn’t any method of taking up slack in the track and a ripple in the top surface of the track is visible as it drives, but the tank is small enough that it doesn’t seem to mind much. STL files and source code is available on GitHub; unfortunately the repository lacks a wiring diagram but between the low component count, photos, and source code that’s not a show-stopper.

Tank treads see a lot of variation, from 3D printed designs for tracks that use a piece of filament as hinges to an attempt to use a conveyor belt as a tank tread for a go-kart. Some tank projects even eschew treads altogether and go for a screw drive.

Dead Simple Ultrasonic Data Communication

June 1, 2018 by Tom Nardi 16 Comments

Some of the best hacks are the ones which seem perfectly obvious in hindsight; a solution to the problem that’s so elegant, you wonder how it never occurred to you before. Of course we also love the hacks that are so complex your eyes start to water, but it’s nice to have a balance. This one, sent in by [Eduardo Zola] is definitely in the former group.

In the video after the break, [Eduardo] demonstrates his extremely simple setup for using ultrasonic transducers for one-way data communication. Powered by a pair of Arduinos and using transducers salvaged from the extremely popular HC-SR04 module, there’s a good chance a lot of readers can recreate this one on their own bench with what they’ve got lying around. In this example he’s sending strings of text from one computer to another, but with a little imagination this can be used for all sorts of projects.

For the transmitter, the ultrasonic transducer is simply tied to one of the digital pins on the Arduino. The receiver is a bit more complex, requiring a LM386 amplifier and LM393 comparator to create a clean signal for the second Arduino to read.

But how does it work? Looking through the source code for the transmitter and receiver, we can see it’s about as basic as it gets. The transmitter Arduino breaks down a given string into individual characters, and then further converts the ASCII to eight binary bits. These bits are sent out as tones, and are picked up on the receiving end. Once the receiver has collected a decent chunk of tones, it works through them and turns the binary values back into ASCII characters which get dumped over serial. It’s slow, but it’s simple.

If you’re looking for something a bit more robust, check out this guide on using GNU Radio with ultrasonics.

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