Indoor Thermometer & Hygrometer

First Steps

For my upcycing project I decided to make a home weather station from some recycled hardwood flooring and some spare electronics I had around the house. To start I used a DHT11 sensor breakout board to sense the current temperature and humidity. These values are read by an Arduino ProMini ($2 from sparkfun’s annual sale a few years ago).

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Next, I chose to use two analog voltmeters to function as a display. I chose to use analog display to give the weather station a 1960’s engineering aesthetic. The output of the voltmeter can be set by varying the duty cycle of the arudino’s pulse width modulation output. I really wanted to use a wifi module to display the current chance of snow and outdoor temperature, but I didn’t have one on hand and figuring out the technical side of it is likely out of scope of this project.

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Design & Construction Process

The design process for the home weather station I built was more iterative than linear. Originally, I planed on using a single piece of barn wood as a faceplate. I intended to mill out two pockets for the indicators and mount the device on the wall – similar to an old fashioned barometer. However, after visiting the wood shop, I discovered that my design was not feasible. The wood was too weathered to be cut with any consistency and the radii that I had called out in my drawings were more appropriate for aluminum than wood. On a mill it is relatively easy to program a tool path to cut a pocket, but the makerspace at the idea forge only has a manual router. I also learned that with wood, it’s difficult to use a router bit that is smaller than 3/8″ diameter. As a consequence, I redrew my design so it would be made of six rectangular slats of recycled flooring.

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The flooring was slightly warped and the surface finish was rough so I refinished the board with a manual planer. I had never used a planer before – I was surprised that the best way to plane wood is by carefully shaving roughly 0.050″ layers of wood off the surface. My first impulse would have been to sand the wood, but apparently that leads to inconsistent results.

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After planing the wood, I used miter and track saws to cut the slats to the right dimensions. Originally, I planned on using butt joints to join the slats with wood glue. While its possible to use a butt joint, the makerspace curator recommended that I add some overlap between the slats with the router for a sturdier build. I cut slots into the top and bottom slats and added a 1/8″ radius to the outer edges to give the device a more finished look. I then stained the wood using a dark oak stain to give the wood a more aged appearance (and to cover up some minor errors).

Once I glued together and stained the case, I realized that I had made a measurement error on the depth of the router cut. I was left with a 1/4″ gap a the top of the indicator. I decided to fix this problem by adding a feature – a 3D printed mount for the indicator and a backlight.

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The mount was designed to hold the indicator tightly and extend it past the face of the wood for a more pronounced effect. I utilized the extra 1/4″ of space by mounting two LEDs underneath the indicator to provide some uplighting. To prevent the light from shining through the plastic and direct the light upward I lined the inside of the mount with aluminum foil. Fortunately, the addition of a backlight improved the project. My measurement error with the router could have been a serious problem.

The next step in the project was to disassemble the analog displays and scan in the faceplates. IMG_1807

After taking the voltmeter apart, I became interested in how it measures the voltage between it’s anode and cathode. It turns out the voltmeter I selected for the project is whats called a d’Arsonval moving-coil galvanometer (source: IHS Engineering 360). It uses a permanent magnet and a fine coil of wire where current flows. As current flows, it creates a magnetic field which causes the needle to deflect.

 

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image credit:  The Free Dictionary

Next, I scanned the faceplates and edited the images in photoshop. I changed the scale to an indoor temperature range of 40 to 100 F. I printed out the new images on card-stock and installed them in the indicator. The indicators have a small screw that adjusts the spring tension and sets the needle position. This allowed me to tune the displays from a known temperature in my house.IMG_1808

Finally, once the housing was built I installed all of the wiring and electronics. It was more difficult than expected trying to get everything connected and working in the case. It was particularly hard to get the soldering right on my back patio during the snowstorm!

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As a final step, I cut apart an old samsung phone charger to serve as a power source for my project. Most phones require a regulated 5v power source to charge. The Arduino ProMini that I used for this project also requires a 5V power source – so I removed the usb connection form the end of the cable and soldered the connections to Arduino. 31AnSkpzJkL

Using a multimeter I measured the current used by the completed project to be about 120 mA. At 5V, the device uses 0.6 W during operation. Assuming the current price of electricity is $0.08 per kilowatt hour in Colorado,tThe weather station could be turned on continuously for a year for under $0.50.

Inspiration

I got the idea for this project by looking through my electronic parts drawer. I’ll often times buy electronics parts I find on spark fun or eBay with the hope of incorporating them into a future project . I purchased the analog displays on Ebay for about $2 each after watching a YouTube video on how an analog voltmeter could be used as a display with a PWM signal.

Analog displays can be used to give a project a pre-digital aesthetic, and surprisingly they are about 2/3 the cost of a 16×2 character LED display.

Vision & Outcome

I wanted this project to be reminiscent of antique scientific and engineering equipment. I’ve always liked the antique barometers/thermometers that you sometimes see as home decoration. The combination of wood and scientific instrumentation evokes the age of exploration and early scientific inquiry. The barometer/thermometer pictured below is a good example of the style. It was restored by Rayment Antiques and auctioned in the UK.

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I was also inspired by the ornate analog displays that were popular in the 1960s and 70s. In high school I learned about the 3 mile island disaster and was surprised by the complexity and analog appearance of the control room. This image shows the reactor control room (remarkably in 1998).

THREE MILE ISLAND, PA.--JULY 14, 1998--Three Mile Island (TMI) Nuclear Plants, the site of the country's worst nuclear accident in 1979, is up for sale by GPU Nuclear, the company that owns and operates the plant. Ken Gramilch, one of the control room operator, monitors instrument panels for the primary nuclear sites of TMI plant. photo by Kenneth K. Lam/staff

Photo credit: Kenneth K. Lam/Baltimore Sun File/July 14, 1998

In this project, I achieved my functional goal of building a working home weather station. Although it only displays temperature and humidity, I could easily add other sensors or incorporate a wifi chip that fetches the current outdoor weather. I was pleased by how the exterior came out. The dark wood stain really improved the overall look of the project. The wood I used was pine, but I was able to achieve the appearance of hardwood like in the antique barometer above. In terms of my artistic goals, I felt that the project conveys the aesthetic I was looking for but the overall results were limited by my woodworking skills and the limited time we had to work on the project. In the future I would like to refine the weather station by adding more analog readouts and perhaps building a case that has a more ornate and victorian feel to it. However, despite it’s limitations I’m happy to have an upcycled weather station on my desk.

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48 Comments. Leave new

Would you consider adding something to it to give you real-time forecasts or show you things like the actual weather outside (ie. Sunny, Cloudy, Rain, etc.)?

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Christopher Coffman
February 8, 2016 9:00 pm

Really impressive use of home electronics. Definitely gives off a retro look, and very technically well done.

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Personally, I like that shade of 3 mile island gamma ray green.

That said I really like the look of this! I’d consider putting a plug on the side of it for an external sensor array. That way it can be either an indoor, and outdoor, or at the touch of a switch, both kinds of meter. Also, they make amber or warm white LEDs. Amber in particular would have a retro look, looking like a nixie tube or a light bulb indicator.

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Ashley Zimmerer
February 8, 2016 1:08 pm

I like how in depth this project is, clearly you put a lot of time into it. The aesthetic is really neat, as is the fact that the device actually works. I like the stain you used for the wood, too. Maybe you could print a custom scale that ties in the darkness of the wood to the display.

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David Holliman
February 8, 2016 9:35 am

Very interesting to learn about antique analog displays. I think if you decide to take this project further, an ornate woodworking design would look really cool.

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Brendan Warren
February 7, 2016 11:33 pm

Incredible use of home electronics. Really came out looking like an antique even though it is packed with electronics.

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Anfal Abdulrahman
February 7, 2016 11:09 pm

I really liked your project in terms of aesthetic and functionality. However, I did not anticipate such a designing process, amazing work. Your report was very informative, too, especially when it came the wood work you did. The wifi idea is very awesome, I really hope this something you might consider for future, I would buy a device like that!

Thank you Nick.

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Was there any reason why you couldn’t reach that last 1/4″ depth on the router, or was just it just an actual tool limitation instead? You also mentioned the use of PWM on this project, but I guess I’m confused to how this plays into the project. From what I see, you’re using a small board to detect voltage swings, but now that I think about it, you’re using PWM for the LEDs? I’m guessing you wrote some code for this. I like that you went and made new templates for the measurements. What material did you print it on? It kind of looks like plastic but I’m not sure. Nice job with the 3D model as well, I’m not sure if this was really that necessary for your project, but hey, it is a nice thing to have to ensure a perfect fit. Great job, the only suggestion I have is to make those displays recessed into the wood. Also having tighter edges would give this a more professional look.

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Shawn Sprinkle
February 6, 2016 6:35 pm

I like the addition of the back light! Really good woodworking too

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Nicholas Flood
February 6, 2016 4:03 pm

The stain/finish looks really good. It would look nicer if the front panel was made from a single sheet of wood. Good job!

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Jason Mcgrath
February 5, 2016 8:40 pm

The vintage engineering aesthetic was very fun to see. The project has a nice mix of art and tech.

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Jacob Mccormick
February 5, 2016 12:49 pm

The aesthetics of the 60’s and 70’s is really apparent in this, and it’s awesome!

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Meridith Richter
February 5, 2016 12:35 pm

Looks really appealing and is a wonderful idea, functionally and artistically.

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Your knowledge of woodworking and electronics is impressive. I really like the aesthetic motivation from the 70’s engineering world. Analog is definitely the way to go over digital. Are you concerned at all with the sensors being too close/enclosed to the box to give accurate readings? Cool project.

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Joseph Yoshimura
February 5, 2016 12:17 pm

One of my favorite things about this is how you made something that is not only functional, but looks great as well! The lighting looks simple yet elegant!

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Wow, this is really involved. I am always looking about temperature and forecast and this is a great solution. I can really appreciate the wood work with minimal experience in the past.

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This came out really nice especially considering it was one of your first times working with wood! I love the aesthetic of the faces.

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This is definitely useful and looks great! I really dig the retro analog tech theme

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Good recovery from measuring error to add backlight. The aesthetic is very clear; makes me nostalgic for the stereo projects I built in the 1970’s.

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You were very clear about your inspiration which was great. Nice and organized presentation (I like the images and the GIFs). Also clear about the process. Very clean final result. Great ideas for improvement. Are you sure you want to keep the casing wood?

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Peter Brunsgaard
February 5, 2016 12:14 pm

You did a great job of making it visually appealing without sacrificing the aesthetic you were going for. Good work!

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Rachel Grosskrueger
February 5, 2016 12:14 pm

I really like your inspiration and how well you stuck with that theme! Very beautiful final product and I really like how you want to continue to improve your design and final product!

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Ryan Yankowsky
February 5, 2016 12:14 pm

Interesting use of old/new technologies to produce a retro (70-80’s tech) with a modern twist. Great idea and great finish.

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Thomas Brunsgaard
February 5, 2016 12:14 pm

You mentioned that you wanted to be able to use this outdoors. Would you have to put it in a case, or are the electronics already reasonable well protected? The woodworking looks great, and I always love Arduino project.

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The woodworking looks great. well executed project!

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Nice work! A lot of hard work went into this. Do you think you could’ve gone for a cheaper solution for the mount? I really enjoy the aesthetics of this. How exactly does the PWM determine the humidity and temperature?

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Elizabeth Whitman
February 5, 2016 12:14 pm

Great job. You have a lot of good ideas for future improvements!

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Wow! That is one of the technically coolest project I have seen to date. I enjoy the 1940’s or 50’s technology aesthetic of the device too.

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The final product is beautiful, your woodworking skills seem more than adequate for this project. Interesting idea and utilization of resources.

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Great result, you nailed the antique measurement device aesthetic. The fact that it works for two different measurements is really cool too, I love the final product.

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Anfal Abdulrahman
February 5, 2016 12:13 pm

I really like this kind of ”engineering” aesthetic. Your project is very classy. Slightly deviated from the initial project but I looks classy and very functional.

Nice work!

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Chip Bollendonk
February 5, 2016 12:13 pm

Fascinating job on this! Definitely looks like you put a lot of engineering thought into this project, I’m pretty jealous. Looks like you could buy it for a not-so-cheap price.

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That looks exceptionally cool. It makes me think of a mad scientist’s lab in the older movies. I enjoy how you made this project dynamic. I also enjoy how it is fairly small and does not take up much space.

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Sreyas Krishnan
February 5, 2016 12:13 pm

Love the retro look. Great suggestions to yourself about how to improve it, too. This would be cool to have sitting on a mantle.

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Samantha Maierhofer
February 5, 2016 12:13 pm

I like that you incorporated electronics into the project. The aesthetics is cool and definitely works well with the function. Great job problem solving with the use of the 3D printer.

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Brittany Warly
February 5, 2016 12:13 pm

This is really impressive. I like how you integrated your engineering knowledge and electrical interests into this project. Also, great job on 3d printing the mount! Really cool looking and will look great in any home.

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Gardner Nichols
February 5, 2016 12:12 pm

Really nice job with the assembly, it looks very high quality! I think your aesthetic of older scientific equipment is well captured and fun. If only the oscilloscopes in the ITLL were as pretty as this!

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I really like the DIY electronics of this project, and the online research that you had to do. Its a neat idea to have a bunch of these dials at home to show different measurements!

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Looks great! It’s much more complex on the inside than I would have expected, does it work well?

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Andre Szlendak
February 5, 2016 12:12 pm

I definitely remember thinking there was much more craftsmanship to electronics and our devices. I love the woodwork and fittings.

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This is a cool project and I liked your explanation of how you got to the final design.

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The woodworking on this project is a standout- very nice. It does feel like the style/aesthetic of the dials are a little mismatched with the wooden casing- the 70’s feel that you showed usually has weird steel or plastic in odd colors. Still an awesome project, though.

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Wow, looks like you put a lot of time into this, from creating the wood casing to fabricating your own gauges. It truly looks like a finished product instead of some college project.

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Jakob Oreskovich
February 5, 2016 12:10 pm

Super aesthetically pleasing! I bet this looks awesome on a shelf/desk. Very impressive build process.

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Awesome project! Love how you really used engineering to design this and turn it into a cool piece of art.

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Wow! This is so cool!! Nice work! Do you have any idea how accurate it is?

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    The data sheet for the sensor I used claims ±5%RH and ±2°C so it’s not terribly accurate. The sensor was only $1.29 though, I could upgrade the project with a more accurate sensor in the future.

    Reply

      In electronics, those tolerances are usually biased towards one end. If you figure out whether it’s plus or minus, you can probably mostly compensate in software.

      Reply

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