Vintage Gauges Turned Classy Weather Display

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.

This Freezer Failure Alarm Keeps Your Spoils Unspoiled

Deep freezers are a great thing to have, especially when the world gets apocalyptic. Of course, freezers are only good when they’re operating properly. And since they’re usually chillin’ out of sight and full of precious goods, keeping an eye on them is important.

When [Adam] started looking at commercial freezer alarms, he found that most of them are a joke. A bunch are battery-powered, and many people complain that they’re too quiet to do any good. And you’d best hope that the freezer fails while you’re home and awake, because they just stop sounding the alarm after a certain amount of time, probably to save battery.

If you want something done right, you have to do it yourself. [Adam]’s homemade freezer failure alarm is a cheap and open solution that ticks all the boxen. It runs on mains power and uses a 100dB piezo buzzer for ear-splitting effectiveness to alert [Adam] whenever the freezer is at 32°F/0°C or above.

If the Arduino loses sight of the DHT22 temperature sensor inside the freezer, then the alarm sounds continuously. And if [Adam] is ever curious about the temperature in the freezer, it’s right there on the 7-segment. Pretty elegant if you ask us. We’ve got the demo video thawing after the break, but you might wanna turn your sound down a lot.

You could assume that the freezer is freezing as long as it has power. In that case, just use a 555.

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Thermochromic Display Tells You The Temperature Despite Your Current Mood

Readers who survived the 1970s will no doubt remember the “mood ring” fad, where a liquid crystal mounted to a ring would magically reveal your current emotional state to all and sundry by changing color. This nifty thermochromic display is based on the same principle, and while it might not start a new craze, it’s still pretty mesmerizing to watch.

This isn’t [Moritz v. Sivers]’ first attempt at a thermochromic display. His earlier version was far more complicated, using separate copper plates clad with thermochromic film for each segment, with Peltier devices to cool and heat them individually. Version two is much simpler, using a printed circuit board with heating elements in the shape of seven-segment displays etched into it. The thermochromic film sits directly on the heater PCB; a control PCB below has the MCU and sensors on it. The display alternates between temperature and humidity, with the segments fading in an uneven and ghostly way that really makes this fun to watch. [Moritz] has made the build files available, and there’s a detailed Instructable as well.

We’re always on the lookout for alternate display modalities, especially when they look this cool. We’ve seen other thermochromic displays before, of course, and persistence of phosphorescence looks great, too.

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A VFD Wall Thermometer

Want to build something using VFD tubes, but don’t need yet another clock project? In that case, this wall mounted temperature and humidity display created by [commanderkull] might be exactly what you’re looking for. With six IV-11 tubes, this display is a practical way to add some of that gorgeous blue-green glow to your home or office.

The USB powered display uses a XL6009 and an XL7015 to provide the 24 V and 1.8 V needed by the IV-11 tubes, respectively. Both of which can be disconnected with jumpers to shut down the tubes without powering off the entire device, a useful feature when programming and debugging the display’s ATmega328P microcontroller. Each tube is connected to the ATmega with an 74HC595 shift register and a UDN2981 driver. Temperature and humidity data is provided, perhaps unsurprisingly, by the exceptionally common DHT22 sensor.

If you are looking to build another clock with these style tubes, there’s certainly enough prior art out there to get you started. We’ve also seen faux VFDs that you could use for either project, just in case you aren’t looking to deal with the voltage requirements and relative rarity of the real thing.

Exploring Basement Humidity With A Raspberry Pi

Sometimes a hack isn’t about building something cool. Sometimes it’s more tactical, where the right stuff is cobbled together to gather the information needed to make decisions, or just to document some interesting phenomenon.

Take this impromptu but thorough exploration of basement humidity undertaken by [Matthias Wandel]. Like most people with finished basements in their homes, [Matthias] finds the humidity objectionable enough to warrant removal. But he’s not one to just throw a dehumidifier down there and forget about it. Seeking data on how well the appliance works, [Matthias] wired a DHT22 temperature/humidity sensor to a spare Raspberry Pi to monitor room conditions, and plugged the dehumidifier into a Kill-A-Watt with a Pi camera trained on the display to capture data on electrical usage.

His results were interesting. The appliance does drop the room’s humidity while raising its temperature, a not unexpected result given the way dehumidifiers work. But there was a curious cyclical spike in humidity, corresponding to the appliance’s regular defrost cycle driving moisture back into the room. And when the dehumidifier was turned off, room humidity gradually increased, suggesting an unknown source of water. The likely culprit: moisture seeping up through the concrete slab, or at least it appeared so after a few more experiments. [Matthias] also compared three different dehumidifiers to find the best one. The video below has all the details.

We always appreciate [Matthias]’ meticulous approach to problems like these, and his field expedient instrumentation. He seems to like his creature comforts, too – remember the target-tracking space heater from a few months back?

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Picking The Right Sensors For Home Automation

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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Ambient Lighting For Baby With The ESP8266

There are plenty of great reasons to have a child. Perhaps you find the idea of being harshly criticized by a tiny person very appealing, or maybe you enjoy somebody screaming nonsense at you while you’re trying to work on something. But for us, we think the best reason for procreation is getting another excuse to build stuff. It’ll be what, at least two years before a baby can solder or program a microcontroller? Somebody’s going to have to do it for them until then.

To try to help his baby daughter get on a better sleep schedule, [Amir Avni] decided to outfit her room with some “smart” lighting to establish when it’s time for her to wake up. Not only can he and his wife control the time the lights come on to “day” mode, but they can also change the colors. For example, they can switch over to a red glow at night. Despite some learning experience setbacks, the both the parents and the baby are very happy with the final product.

An ESP8266 controls a WS2812 LED strip to provide the adjustable lighting, and a DHT22 sensor was added to the mix to detect the temperature and humidity in the baby’s room. [Amir] used Blynk to quickly throw together a slick mobile application that allows for complete control of the brightness and color of light in the room, as well as provides a readout of the environmental data pulled from the DHT22.

But not everything went according to plan. [Amir] thought he could power the LED strip from the ESP8266 development board by soldering to the 5 V side of its AMS1117 voltage regulator. Which worked fine, until he turned on too many LEDs. Then it pulled too much current through a resistor connected to the regulator, and let all the magic smoke out. An important reminder of what can happen when we ask more of a circuit than what it was designed for.

We’ve covered many awesome projects that were born of a parental need, from feature packed baby monitors to devices seemingly designed to program nostalgia in the little one’s subconscious.