ESP8266 Home Monitor Is Stylishly Simplistic

November 20, 2017 by Tom Nardi 18 Comments

It’s often said that “Less is More”, and we think that the chic ESP8266 environmental monitor posted by Thingiverse user [bkpsu] definitely fits the bill. Dubbed “Kube”, the device is a 3D printed white cube with an OLED display in the center, which [bkpsu] says was designed specifically for the approval of his wife. Weirdly, she didn’t like the look of bare PCBs on the wall.

Multiple Kubes allow for whole-house monitoring.

Inside, things are a little more complex. The Kube uses the NodeMCU development board, and a custom breakout that [bkpsu] designed to interface with the display and sensors. For temperature and humidity monitoring, the Kube is using the ever-popular DHT22, and [bkpsu] mentions that he has future plans for things like motion sensors and direct control of RGB LED strips. All the data collected by the Kube is piped into openHAB via MQTT.

On the very detailed Thingiverse page, [bkpsu] gives background information on his design goals for the project, tips for printing out a high-quality case, a parts list with Amazon links, and pinout information for getting it all wired up. The PCB is even available on OSH Park for those who want a Kube of their own.

Even with all the stick home monitoring and automation products on the market today, many hackers simply can’t bring themselves to buying a turn-key commercial product. But we think with the results hackers have been getting rolling their own solutions, they just might be on to something.

Hacking The IKEA Trådfri Light Bulb

November 17, 2017 by John Baichtal 13 Comments

[BasilFX] wanted to shoehorn custom firmware onto his IKEA Trådfri light bulb. The product consists of a GU10-size light bulb with a LED driver as well as IKEA’s custom ZigBee module controlling it all. A diffuser, enclosure shell, and Edison-screw base give the whole thing the same form factor as a standard A-series bulb. The Trådfri module, which ties together IKEA’s home automation products, consists of an ARM Cortex M4 MCU with integrated 2.4Ghz radio and 256 Kb of flash — not bad for 7 euros!

Coincidentally, [BasilFX] had just contributed EFM32 support to RIOT-OS (“the friendly OS for IoT”) so he was already halfway there. He used a JTAG/SWD-compatible debugger to flash the chip on the light bulb while the chip was still attached.

[BasilFX] admits the whole project is a proof of concept with no real use yet, though he has turned his eye toward getting the radio to work, with a goal of creating a network of light bulbs. You can find more info on his code repository.

We ran a post on Trådfri hacking earlier this year, as well as one on the reverse-engineering process used to suss out the bulb’s secrets.

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“Hey! Don’t Lock The Door, I’m In Here!”

November 13, 2017 by Dan Maloney 24 Comments

Those that work in front of a computer for a living spend most of the time making very little sound. Unless you’re a member of the clicky mechanical keyboard club, your working time is a low-observables time during which people can forget about you. You can make sure you’re not overlooked with this smartphone hotspot presence detector.

[Emilio Ficara]’s quiet work habits resulted in his housemates locking him in sometimes, to his inconvenience. PIR or microwave occupancy sensors might have worked to fix the problem, except that a few flexing fingers aren’t always enough to trigger them. Luckily, [Emilio] is also wisely distrustful of free WiFi, so his phone is always set up as a mobile hotspot, giving him the means to reliably detect his presence. An ATtiny2313 and an ESP-01 do the business of polling for the SSID of his phone and blinking a bright blue LED by his door for his housemates. It’s not perfect, of course; it could easily be spoofed by anyone else who knows his SSID. But simple works for now.

With almost everyone carrying one now, smartphone detection is a good proxy for the presence of a person. But it doesn’t work in every case, so you may want to familiarize yourself with the aforementioned PIR and microwave methods.

A Motion Sensing Light For Your Entrance Hallway

November 11, 2017 by James Hobson 25 Comments

Arriving home to a dark house with an armful of anything is usually an exercise in fumbling confusion until someone manages to turn on a light. [Pavel Gesyuk] has circumvented this problem entirely by building and installing a motion detecting entrance light!

[Gesyuk] is using an Arduino clone by the name of Funduino Mini Pro, a 2-channel, 2-way relay, — he only needed one, but you use what you have on hand — a recycled power supply to convert 220V AC to 5V DC, and an infrared sensor.

The project’s goal — in excess of a lighting solution for an entrance hallway — was the learn the ins and outs of the Arduino and motion sensors. After some initial hurdles familiarizing himself with the Arduino, [Gesyuk] wired everything together on a protoboard and stuck it in a plastic case — loose wires in a high traffic area doesn’t a safe home make.

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Measuring Airflow In An HVAC System

November 4, 2017 by John Baichtal 10 Comments

[Nubmian] wrote in to share his experiments with measuring airflow in an HVAC system. His first video deals with using with ultrasonic sensors. He found an interesting white paper that described measuring airflow with a single-path acoustic transit time flow meter. The question was, could he get the same effects with off-the-shelf components?

[Nubmian] created a rig using a pair of typical ultrasonic distance sensors. He detached the two transducers from the front of the PCB. The transducers were then extended on wires, with the “send” capsules together pointing at the “receive” capsules. [Nubmian] set the transducers up in a PVC pipe and blew air into it with a fan.

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Coffee, Conspiracy, And Citizen Science: An Introduction To Iodometry

October 30, 2017 by Sean Boyce 40 Comments

I take coffee very seriously. It’s probably the most important meal of the day, and apparently the largest overall dietary source of antioxidants in the United States of America. Regardless of whether you believe antioxidants have a health effect (I’m skeptical), that’s interesting!

Unfortunately, industrially roasted and ground coffee is sometimes adulterated with a variety of unwanted ‘other stuff’: corn, soybeans, wheat husks, etc. Across Southeast Asia, there’s a lot of concern over food adulteration and safety in general, as the cost-driven nature of the market pushes a minority of vendors to dishonest business practices. Here in Vietnam, one of the specific rumors is that coffee from street vendors is not actually coffee, but unsafe chemical flavoring agents mixed with corn silk, roasted coconut husks, and soy. Local news reported that 30% of street coffee doesn’t even contain caffeine.

While I’ve heard some pretty fanciful tales told at street side coffee shops, some of them turned out to be based on some grain (bean?) of truth, and local news has certainly featured it often enough. Then again, I’ve been buying coffee at the same friendly street vendors for years, and take some offense at unfounded accusations directed at them.

This sounds like a job for science, but what can we use to quantify the purity of many coffee samples without spending a fortune? As usual, the solution to the problem (pun intended) was already in the room:

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Junkbox Freezer Alarm Keeps Steaks Safe

October 29, 2017 by Dan Maloney 24 Comments

A fully stocked freezer can be a blessing, but it’s also a disaster waiting to happen. Depending on your tastes, there could be hundreds of dollars worth of food in there, and the only thing between it and the landfill is an uninterrupted supply of electricity. Keep the freezer in an out-of-the-way spot and your food is at even greater risk.

Mitigating that risk is the job of this junkbox power failure alarm. [Derek]’s freezer is in the garage, where GFCI outlets are mandated by code. We’ve covered circuit protection before, including GFCIs, and while they can save a life, they can also trip accidentally and cost you your steaks. [Derek] whipped up a simple alarm based on current flow to the freezer. A home-brew current transformer made from a split ferrite core and some magnet wire is the sensor, and a couple of op-amps and a 555 timer make up the detection and alarm part. And it’s all junk bin stuff — get a load of that Mallory Sonalert from 1983!

Granted, loss of power on a branch circuit is probably one of the less likely failure modes for a freezer, but the principles are generally applicable and worth knowing. And hats off to [Derek] for eschewing the microcontroller and rolling this old school. Not that there’s anything wrong with IoT fridge and freezer alarms.

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