Picking The Right Sensors For Home Automation

April 16, 2019 by Maya Posch 22 Comments

Imagine that you’re starting a project where you need to measure temperature and humidity. That sounds easy in the abstract, but choosing a real device out of many involves digging into seemingly infinite details and trade-offs that come with them. If it’s a low-stakes monitoring project, picking the first sensor that comes to mind might suffice. But when the project aims to control an AC system in an office of temperature-sensitive coders, it pays to take a hard look at the source of all information: the sensor.

Continuing a previous article I would like to use that same BMaC project from that article as a way to illustrate how even a couple of greenhorns can figure out how to pick everything from environmental sensors to various actuators, integrating it into a coherent system that in the end actually does what it should.

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A Simple Programmable Light Controller

April 11, 2019 by Lewin Day 5 Comments

Everything’s internet connected these days, garage doors, baby monitors, and the kitchen sink are all hooked up. There are benefits to having everything online, but also several pitfalls. Maintaining security on a home network is an ongoing job, made more difficult by the number of devices that must be kept track of. Sometimes all the hassle isn’t worth it, and you just want a non-connected solution. [Dilshan] found himself in just that camp, and built a simple programmable light controller that doesn’t connect to the Internet.

At the core of the project is an ATMEGA8 microcontroller, which is cheap, readily available, and can do the job. It’s combined with a DS1307 real time clock IC to keep track of time. The circuit is designed for 24V power, to allow it to be run from the same supply as the LED light modules it is designed to control.

The design was initially prototyped with through-hole parts on the breadboard, with the final design being built with surface mount parts on a custom PCB. Light is courtesy of a 7W warm white LED module. 3 push buttons and a 4-digit, 7-segment display act as the user interface, with an LDR to allow the light to also react to its surroundings.

It’s a build that goes against current trends, lacking WiFi connectivity, Twitter functionality, or cloud-based logging. It goes to show that the right solution isn’t always putting everything online. Sometimes the old methods are enough to do the job, and do it well.

Of course, if you’re still itching for a packet data fix, here’s how to blink an LED over the Internet.

Transcending The Stack With The Right Network Protocol

April 9, 2019 by Maya Posch 14 Comments

The increase in network-connected devices the past years has been something of a dual-edged sword. While on one hand it’s really nice to have an easy and straight-forward method to have devices talk with each other, this also comes with a whole host of complications, mostly related to reliability and security.

With WiFi, integrating new devices into the network is much trickier than with Ethernet or CAN, and security (e.g. WPA and TLS) isn’t optional any more, because physical access to the network fabric can no longer be restricted. Add to this reliability issues due to interference from nearby competing WiFi networks and other sources of electromagnetic noise, and things get fairly complicated already before considering which top-layer communication protocol one should use. Continue reading “Transcending The Stack With The Right Network Protocol” →

DIY Air Conditioner Built From Weird Donor Appliance

April 7, 2019 by Al Williams 64 Comments

There are some parts of the world where living without air conditioning borders on unthinkable. But in more moderate climates, it isn’t all that unusual. [Josh’s] apartment doesn’t have central air conditioning — the kind that connects to a forced-air heating/cooling system. It does, though, have a water circuit for air conditioning, so he decided to hack a few experimental air conditioners.

He’s not starting completely from scratch. The two attempts he made at building his AC came from donor parts. The successful one started out as a hot water heater. The very first attempt didn’t quite work as well, using a refrigerator compressor and an evaporator from a baseboard heater. The flow control through the heat exchanger turns out to be very tricky, so [Josh] claims he mostly got ice right at the inlet and minimal cooling through the evaporator.

The more successful one works better but still has a problem with the evaporator freezing that he’s trying to solve. He’s looking for suggestions on how to make it work better. As much as we like a good hack, our advice is to move to a different apartment building.

We’ve seen other homemade coolers, but they are more like swamp coolers. If you just need to cool your desk, you might just get some ice in a metal can.

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A Contact Lens Launcher That Knows The Weather

April 7, 2019 by Tom Nardi 10 Comments

They say that necessity is the “Mother of Invention”, but over the years we’ve started to suspect that her cousin might be an underutilized microcontroller. How else can you explain projects like the latest from [MNMakerMan], which takes the relatively simple concept of a contact lens holder and manages to turn it into an Internet-connected electronic appliance? Not that we’re complaining, of course.

He started out with a simple 3D printed holder for his wall that would let him pull out his daily lenses, which worked well enough and gained some popularity on Thingiverse. But he wondered if there wasn’t some way he could use a servo to automate the process. While he was at it, he might as well play with some of the components he’s been meaning to get some hands-on experience with, such as those little OLED displays all the cool kids are using.

Modifying his original design to incorporate servos in the bottom, he added a central compartment that would house an ESP8266 and a simple proximity sensor made from an IR LED and photodiode. The sensor tends to be a little twitchy, so he left a potentiometer inside the device so he can fine tune it as needed.

Strictly speaking the OLED display isn’t actually required for this project, but since he had a WiFi capable microcontroller sitting there doing basically nothing all day anyway, he added in a feature that shows the weather forecast. It’s not much of a stretch to say that the first thing you’d want to see in the morning after regaining the sense of sight is a readout of what the day’s weather will be, so we think it’s a fairly logical extension of the core functionality. Bonus points if he eventually adds in a notification to remind him it’s time to order more lenses when the dispenser starts getting low.

If you don’t have any contact lenses you need dispensed, never fear. A similar concept can be used to fire off your customized swag at hacker events. Don’t have any of that either? Well in that case you can always build a candy dispenser for Halloween.

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Schrödinger Quantum Percolator Makes Half Decent Coffee

April 1, 2019 by Sean Boyce 34 Comments

I couldn’t decide between normal and decaffeinated coffee. So to eliminate delays in my morning routine, and decision fatigue, I’ve designed the Schrödinger Quantum Percolator — making the state of my coffee formally undecidable until I drink it.

At its core, the Quantum Percolator contains a novel quantum event detector that uses electron tunneling to determine whether to use caffeinated or decaffeinated coffee. The mechanical components are enclosed in an opaque box, so I can’t tell which type of coffee is being used.

The result is coffee that simultaneously contains and does not contain caffeine – at least until you collapse the caffeination probability waveform by drinking it. As the expression goes, you can’t have your quantum superposition of states and drink it too!

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Ikea Furniture Hacks Make Accessibility More Accessible

March 31, 2019 by Roger Cheng 11 Comments

The ThisAbles project is a series of 3D-printed IKEA furniture hacks making life easier for those without full use of their bodies. Since IKEA furniture is affordable and available across most of the planet, it’s the ideal target for a project that aims to make 3D-printed improvements accessible to everyone.

These hacks fit all meanings of the word “accessible”: Available worldwide, affordable, and helping people overcome physical barriers of everyday living. ThisAbles has support of multiple organizations including IKEA Israel. In their short introductory video (embedded below the break) they explained their process to find ways to make big impacts with simple 3D-printed modifications. From bumpers protecting furniture against wheelchair damage, to handles that allow drawers to be opened without fine fingertip control. Each of these designs also fit the well-known IKEA aesthetic, including their IKEA style illustrated manuals.

The site launched with thirteen downloadable solutions, but they have ambitions for more with user feedback. There’s a form where people can submit problems they would like to see solved, or alternatively, people can submit solutions they’ve already created and wish to share with the world. Making small changes to commodity IKEA furniture, these 3D printed accessories will have far more impact on people’s lives than the average figurine trinket on Thingiverse. It’s just the latest way we can apply hacker ingenuity to help others to do everything from simple daily tasks to video gaming.

[via Washington Post]

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