home hacks

1788 Articles

Hack My House: UL Certification And Turning The Lights On With An ESP8266

April 22, 2019 by 48 Comments

It’s hard to imagine a smart house without smart lighting. Maybe it’s laziness, but the ability to turn a light on or off without walking over to the switch is a must-have, particularly once the lap is occupied by a sleeping infant. It’s tempting to just stuff a relay in the electrical boxes and control them with a Raspberry Pi or micro-controller GPIO. While tempting, get it wrong and you have a real fire hazard. A better option is one of the integrated WiFi switches. Sonoff is probably the most well known brand, producing a whole line of devices based on the ESP8266. These devices are powered from mains power and connect to your network via WiFi. One disadvantage of Sonoff devices is they only work when connected to Sonoff’s cloud.

Light switches locked in to a cloud provider are simply not acceptable. Enter Tasmota, which we’ve covered before. Tasmota is an open source firmware, designed specifically for Sonoff switches, but supporting a wide range of ESP8266 based devices. Tasmota doesn’t connect to any cloud providers unless you tell it to, and can be completely controlled from within a local network.

Certifications, Liability, and More

We’re well acquainted with some of the pitfalls of imported electronics, but one of the lesser known problems is the lack of certification. In the United States, there are several nationally recognized testing laboratories: Underwriters Laboratories (UL) and Intertek (ETL) are the most prominent. Many  imported electronic devices, including Sonoff devices, do not have either of these certifications. The problem with this is liability, should the worst ever happen and an electrical fire break out. The Internet abounds with various opinions on the importance of the certification — a missing certification mark is somewhere between meaningless and a total hazard. The most common claim is that a house fire combined with non-certified equipment installed would result in an insurance company refusing to pay.

Rather than just repeat this surely sage advice from the Internet, I asked my insurance agent about uncertified equipment in the case of a fire. I discovered that insurance agencies avoid giving definite answers about claim payments. The response that came back was “it depends”: homeowner’s insurance covers events that are accidental and sudden. If a homeowner was aware that they were using uncertified equipment, then it could be categorized as “not an accident”. So far, the myth seems plausible. The final answer from the insurance agency: it’s possible that a non UL-certified device could result in denial of payment on a claim, but it depends on the policy and other details– why take the risk? Certification marks make insurance companies happier.

I also talked to my city’s electrical inspector about the issue. He commented that non-certified equipment is a violation of electrical code when it is hard-wired into a house. He echoed the warning that an insurance company could refuse to pay, but added that in the case of injury, there could be even further liability issues. I’ve opted to use certified equipment in my house. You’ll have to make your own decision about what equipment you’re willing to use.

There are some devices on Amazon that claim to have certification, but searching the certification database leads me to believe that not all of those claims are valid. If in doubt, there is a searchable UL database, as well as a searchable Intertek database.
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Teardown: The Guts Of A Digital Sentry

April 18, 2019 by 6 Comments

I have a home alarm system that has me wondering if I can make it better with my maker Kung-fu. Recently we had to replace our system, so I took the time to dissect the main controller, the remote sensors, and all the bits that make a home security system work.

To be precise, the subject of today’s interrogation is a Zicom brand Home Alarm that was quite famous a decade ago. It connects to a wired telephone line, takes inputs from motion, door, and gas sensors, and will make quite a racket if the system is tripped (which sometimes happened accidentally). Even though no circuits were harmed in the making of this post, I assure you that there are some interesting things that will raise an eyebrow or two. Lets take a look.

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Cocktail Barbot Takes Things Up A Level

April 17, 2019 by 7 Comments

Mixing a cocktail is considered as much an art as a science. The practice is studied dilligently by bartenders the world over. Of course, for any given human task, there’s always another human building a robot to automate it. [CamdenS5] is one such human, with a cocktail mixing barbot with a few tricks up its sleeve.

As you’d expect, there’s a smattering of the usual alcoholic liquids and mixers, along with a battery of pumps for fluid delivery. The fun doesn’t end there, though. There’s a linear actuator capable of putting out 500 N for slicing limes, and a mint and sugar dispenser as well. If that wasn’t enough, there’s even a muddling station to help bring out the flavours just right.

This is a machine that takes a broader look at the process behind making a good cocktail. It’s not just about lumping ingredients into a glass – it takes finesse and care to get the best results. It’s not the first barbot we’ve seen – this one is built in a grandfather clock.

Picking The Right Sensors For Home Automation

April 16, 2019 by 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 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 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 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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