temperature sensor

34 Articles

Vintage Gauges Turned Classy Weather Display

August 8, 2020 by 4 Comments

It’s always good to see old hardware saved from the junk pile, especially when the end result is as impressive as this analog gauge weather display put together by [Build Comics]. It ended up being a truly multidisciplinary project, combing not only restoration work and modern microcontroller trickery, but a dash of woodworking for good measure.

Naturally, the gauges themselves are the real stars of the show. They started out with rusted internals and broken glass, but parts from a sacrificial donor and some TLC from [Build Comics] got them back in working order. We especially like the effort that was put into making the scale markings look authentic, with scans of the originals modified in GIMP to indicate temperature and humidity while retaining the period appropriate details.

To drive the 1940s era indicators, [Build Comics] is using an Arduino Nano and a DHT22 sensor that can detect temperature and humidity. A couple of trimmer pots are included for fine tuning the gauges, and everything is mounted to a small scrap of perfboard hidden inside of the custom-made pine enclosure.

This is hardly the first time we’ve seen analog gauges hooked up to modern electronics, but most of the projects are just that: modern. While the end look might be somewhat polarizing, we think maintaining the hardware’s classic style was the right call.

MenoPlay Through The Pain Of Menopause

August 4, 2020 by 7 Comments

Menopause, that fireworks finale of fertility, is like a second puberty that works in reverse. At least, that’s what we hear. Along with mood swings and acne, there are new joys like hot flashes that make you want to jump naked into the nearest snowdrift, or at least put your head in the freezer for a while. Sounds great; can’t wait.

The biggest problem with menopause is that it gives suffers pause when it comes to getting help. This is natural, they think. There’s nothing I can do but ride it out. Those who do seek relief are likely to find expensive products that only treat single symptoms. This dearth of solutions inspired [Moinak Ghosh] to create one system to rule them all, a wearable with a suite of sensors that’s designed to take the pause out of menopause.

MenoPlay will take temperature readings at the neck and pelvis and switch on a Peltier module worn on the back of the neck when it senses a hot flash in progress. Exercise is a natural defense against hormonal imbalance, but step counters are too easy to cheat or ignore. The MenoPlay system will model the user’s movements using 9DoF accelerometers and suggest exercises that fill in the gaps.

We particularly like the automation aspect of this wearable. After decades of manually tracking menstrual cycles and everything that implies, the idea of so much useful biological data being collected automatically and fed over BLE to a NodeRed application sounds wonderful.

Hot flashes may not feel useful internally, but would do a fine job of powering the right kind of flashlight.

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Smoking Meat With A Commodore 64

July 27, 2020 by 27 Comments

When [Deadline] couldn’t find a replacement control module for his Masterbuilt electric smoker, he could have just tossed the thing in the trash. Instead, he decided to come up with his own system to take over for the smoker’s original brain. Basing it around the nearly 40 year old Commodore 64 probably wouldn’t have been our first choice, but it’s hard to argue with the end result.

Connectors to control the smoker’s hardware.

At the most basic level, controlling an electric smoker like this only requires a temperature sensor, a relay to control the heating element, and something to get those two devices talking to each other. But for the best results you’ll also want some kind of a timer, and an easy way to change the target temperature on the fly. Connecting the relay and temperature sensor up to the back of the C64 was easy enough, all he had to do was write the BASIC code to glue it all together.

This hack was made considerably easier thanks to the fact that the Masterbuilt’s original controller interfaced with the smoker by way of a couple relatively well documented connectors. So instead of having to mess with any of the mains voltage electronics, he simply had to bring a wire in the connector high to fire up the smoker’s heating element. This bodes well for anyone looking to replace the controller in a similar smoker, with a C64 or otherwise.

In the past we’ve seen some very impressive custom smoker controllers that look as though they could easily be adapted for use with these commercial units. Though the true smoke aficionados might prefer building the entire thing to their exacting specifications.

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An ESP8266 Environmental Monitor In Your USB Port

January 8, 2020 by 28 Comments

At this point, we’ve all seen enough ESP8266 “weather stations” to know the drill: you just put the ESP and a temperature sensor inside a 3D printed case, and let all those glorious Internet Points™ flow right on in. It’s a simple, and perhaps more importantly practical, project that seems to never get old. But that doesn’t mean there isn’t room for innovation.

Annoyed by the unnecessary bulk of existing solutions, [cperiod] has come up with an ESP8266 temperature and humidity sensor that can plug directly into a standard USB port. Slotted into a USB wall charger or power bank, this diminutive board can provide inconspicuous remote environmental monitoring wherever you need it. For extra hacker points, the board was even produced at home on a PCB mill.

In addition to the ESP-7 or 12 module (which plugs in via a header, should you need to swap it out), the board features a CH330N USB to UART chip and HT7233 voltage regulator. For the sensor itself, [cperiod] has bucked convention a bit and went with the I2C-connected AHT10 over something more common like a member of the BME family.

Unfortunately, this design suffers from the same issue we’ve seen in other compact environmental monitoring solutions; namely, that the heat generated by the chip itself skews the temperature readings. To combat this, aggressive power saving functions are baked into the firmware to make sure the ESP is in a deep sleep as much as possible. While not a perfect solution, it does prevent the ESP from warming the PCB up so much that it invalidades the reported data.

By now, the particularly astute reader may have realized that all the additional components used for the USB side of this board aren’t strictly necessary. After all, if you can pull the ESP module out of the header and program it separately, then you don’t actually need to include that capability in each sensor node. While true, we’re hardly the ones to complain when a hacker showboats a bit on their designs.

Dip Your Toes In The Open Water Of Raspipool

October 9, 2019 by 25 Comments

If you’re lucky enough to have a swimming pool, well, you may not feel all that lucky. Pools are great to have on a hot summer day, but keeping them crystal clear and pH-balanced is a deep dive into tedium. Sure, there are existing systems out there. They cost a kiddie pool of cash and are usually limited to particular pool parts. Existing DIY solutions are almost as bad, and so [segalion] is making waves with a dumb, brand-agnostic pool automation system called Raspipool.

Sensors for pH, ORP, and temperature are immersed in pool water flowing through a bypass pipe that runs between the filter and the pump. The basic plan is to control the pumps and sensors with a web-enabled Raspberry Pi, and have the Pi send action and threshold notifications straight to [segalion]’s poolside lounge chair. Each piece is dedicated to a single task, which allows for easy customization and future expansion.

[segalion] is trying to get more people involved so that Raspipool can keep really make a splash. Be sure to check out the project wiki and let him know if you can help or have suggestions.

We’re glad [segalion] is building from the ground up, and doesn’t have to dive into some pre-existing mess of an automation system.

The Danish Internet Of Hot Tubs

August 24, 2019 by 2 Comments

Every hacker camp has its own flavor, and BornHack 2019 in the Danish countryside gave us the opportunity to sample some hacker relaxation, Scandinavian style. Among the attractions was a wood-fired hot tub of gargantuan proportions, in which the tired attendee could rejuvenate themselves at 40 Celcius in the middle of the forest. A wood-fired hot tub is not the easiest of appliances to control, so to tame it [richard42graham] and a group of Danish hackerspace friends took it upon themselves to give it an internet-connected temperature sensor.

The starting point was a TMP112 temperature sensor and an ESP8266 module, which initially exposed the temperature reading via a web interface, but then collapsed under too much load. The solution was to make the raw data available via MQTT, and from that create a web interface for the event bar, Twitter and IRC bots. There was even an interface to display hot tub temperature on the ubiquitous OHMlights dotted around the camp.

It’s more normal to control a hot tub via an electric heater, but since the wood fire on this one has to be tended by a camp volunteer it made sense to use the IRC system as an alert. It will be back at BornHack 2020, so we’ll have to do our job here at Hackaday and spend a long time lounging in the hot tub in the name of journalistic research to see how well it works.

An Epic Tale Of Thermistors: Tricks For Much Better Temperature Sensing

July 21, 2019 by 23 Comments

For years [Edward] has been building professional grade underwater sensing nodes at prices approachable for an interested individual without a government grant. An important component of these is temperature, and he has been on a quest to get the highest accuracy temperature readings from whatever parts hit that sweet optimum between cost and complexity. First there were traditional temperature sensor ICs, but after deploying numerous nodes [Edward] was running into the limit of their accuracy. Could he use clever code and circuitry to get better results? The short answer is yes, but the long answer is a many part series of posts starting in 2016 detailing [Edward]’s exploration to get there.

Orange is 12 bits, red is 24

The first step is a thermistor, a conceptually simple device: resistance varies with temperature (seriously, how much more simple can a sensor get?). You can measure them by tapping the center of a voltage divider the same way you’d measure any other resistance, but [Edward] had discarded this idea because the naive approach combined with his Arduino’s 10 bit ADC yielded resolution too poor to be worthwhile for his needs. But by using the right analog reference voltage and adjusting the voltage divider he could get a 20x improvement in resolution, down to 0.05°C in the relevant temperature range. This and more is the subject of the first post.

What comes next? Oversampling. Apparently fueled by a project featured on Hackaday back in 2015 [Edward] embarked on a journey to applying it to his thermistor problem. To quote [Edward] directly, to get “n extra bits of resolution, you need to read the ADC four to the power of n times”. Three bits gives about an order of magnitude better resolution. This effectively lets you resolve signals smaller than a single sample but only if there is some jitter in the signal you’re measuring. Reading the same analog line with no perturbation gives no benefit. The rest of the post deals with the process of artificially perturbing the signal, which turns out to be significantly complex, but the result is roughly 16 bit accuracy from a 10 bit ADC!

What’s the upside? High quality sensor readings from a few passives and a cheap Arduino. If that’s your jam check out this excellent series when designing your next sensing project!