Electric Lawn Mower Converted To RC Control

June 28, 2015 by Rich Bremer 39 Comments

Not too many people like pushing a lawn mower around the yard, but unfortunately, it is a necessary chore. Anti-push-mower advocate [imadethis2014] decided to (as his moniker suggests) make a solution to his pushing-problem. He was a fan of radio controlled devices so it made sense to convert his mower to RC!

The mower itself is powered by an off the shelf battery and has a 21-inch deck. The stock wheels and handle were removed and replaced with a new extruded aluminum frame. Out back are a pair of used electric wheelchair motors sourced from eBay. These drive motors are mounted to the new frame via a pair of aluminum brackets that [imadethis2014] designed and cut out on his Shakepoko CNC machine. Since both rear drive wheels work independent of each other, a pair of swiveling casters up front allow the mower to turn.

A large car-sized battery box houses the two smaller wheel chair batteries as well as the motor control and RC electronics. Check out the video after the break, the mower seems to do fairly well. [imadethis2014] admits he needs some new wheels as the current ones don’t get a lot of traction on the grass. He’s also thinking of adding GPS for automated mowing but isn’t quite there yet.

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Wirelessly Weighing Plants With The ESP8266

June 28, 2015 by Eric Evenchick 17 Comments

There’s a good number of hacks, and commercial products, for telling you when a plant needs watering. Most of them use an ADC to measure the resistance in the soil. As the soil’s moisture content drops, the resistance increases. High impedance, dead plant.

[squix]’s Thirsdee takes a different approach to plant health monitoring. Instead of measuring resistance, it simply weighs the plant. As the soil dries up, it gets lighter. By measuring the change in weight, the amount of water in the pot can be estimated.

Thirsdee uses a load cell to measure the weight. It’s read using an HX711 ADC, which is controlled by a NodeMCU. This development board is based on the ESP8266 chip. Since Thirsdee has WiFi, it can push notifications to your phone and log data on ThingSpeak. If you’re looking at the plant, an OLED shows you the current status of the plant. For us viewing from home, we can see a graph of [squix]’s plant drying out in real time.

[squix] provides us with a list of suppliers for the parts, and all the source code on Github.

Crawlspace Warehouse Includes Midget Forklift

June 24, 2015 by James Hobson 32 Comments

Meet [Cliff Stoll], producer and entrepreneur-extraordinaire of the ACME Klein Bottles. Years back he helped a friend program a glass oven to get the right temperature profiles for glass blowing. When asked how he wanted to get paid for his help, he asked if they could blow a Klein bottle — and so they did.

Excited at the prospect of his creation, he showed it around to some friends, and was surprised to find out that people wanted to buy it! The one he created took 3 days of sweat and tears to build, so he wasn’t about to start manufacturing them himself. Instead, he decided to call around to some glass manufacturers and see how much he could get Klein bottles made for… That’s when he discovered the power of buying in large quantities.

So what do you do with over 1000 Klein bottles? You build a mini-warehouse in your crawlspace — that’s what.

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Wireless Weather Station

June 22, 2015 by Anool Mahidharia 12 Comments

High schooler [Vlad] spent about a year building up his battery-operated, wireless weather station. Along the way, not only has he learnt a lot and picked up useful skills, but also managed to blog his progress.

The station measures temperature, humidity, pressure and battery voltage, and he plans to add sensors for wind speed, wind direction and rainfall soon. It is powered via a solar panel and can run on a charged battery for a full month. The sensor module transmits data to a remote receiver connected to a computer from where it is published to the internet. Barometric pressure is measured using the BMP180 and the DHT22 provides temperature and humidity values. The link between the transmit and receive sections uses a 433MHz Superhetrodyne RF Kit which gives [Vlad] a range of 50m. There’s an ATMega328 on the transmitter and receiver side. He’s taking measurements once every 12 minutes, and putting the micro controller in low power mode using the Rocket Scream Low Power Library. A 5W, 12V solar panel charges the 6V Lead Acid battery via a LM317 based charge circuit. This ensures the battery gets charged even when the solar panel is not receiving optimal radiation. One hour of sunlight provides enough charge to keep it going for 2 days. And a fully charged battery will keep it running for a full month even when there’s no sunlight.

The server software consists of two parts. The first pushes serial data to a mySQL database. This is written in Visual Studio C# using help from Oracle mySQL connector. The second part publishes the entries in the mySQL database to the web server. This is written in php, and uses Libchart for graphing. He’s got the code, schematics, parts list and a lot of other information available for download on his blog. There’s a couple of items pending on his to-do list, so if you have any tips to offer post your comments below.

Arduino Controlled Air Conditioner

June 11, 2015 by Rich Bremer 31 Comments

Now that summer is coming, it’s time to break out the Air Conditioners! There are some old AC units out there that still work just fine, but nowadays we are used to everything being remotely controlled and automatic. [Phil] had an old window-mounted AC unit that still worked but was installed in a not-so-convenient place. To access the AC’s controls, one would have to climb over a large desk. This is a perfect opportunity to use the plethora of widely available hobby electronics to make an automatic AC controller retrofit.

First things first, there needs to be a way to turn the current control knob on the AC. [Phil] modeled up a 3D bracket to hold an RC car servo to the AC control panel. Attached to the servo horn is a slotted cylinder sized appropriately to fit the shape of the control knob. An Arduino measures the temperature of the room via a DS18B20 temperature sensor which then has the servo turn the control knob to the appropriate position, on or off. The Arduino sends temperature data back to a PC via MegunoLink Pro which graphs past data and also displays current temperature data. Using MegunoLink Pro, the min/max temperature points can also be set without uploading a new sketch to the Arduino.

From the temp vs time graph, it looks like the room temperature stays a consistent 23 +/- 1 °C. [Phil] did us summer-swelterers a favor and made all his design files available. This is a great idea but wonder if leaving the air conditioner unit switch in the ‘on’ position and turning the unit on/off via a relay connected to the 120vac line would work just as well.

Flat Pack Elastic Band Lamp Is A Thing Of Beauty

June 3, 2015 by Rick Osgood 13 Comments

[Matt] was looking for a project for his senior industrial design studio at Wentworth Institute of Technology. He ended up designing a clever lamp that can be flat packed. [Matt] started by drawing out designs on paper. He really liked the idea of combining curves with straight lines, but he wanted to translate his two-dimensional drawings into a three-dimensional shape.

Having access to a laser cutter made the job much easier than it could have been and allowed [Matt] to go through many designs for the lamp frame. The two main pieces were cut from acrylic and include mounting pegs for the elastic bands. The two plastic pieces are designed to slot together, forming a sort of diamond shape.

The final version of the lamp required that the elastic bands had holes punched in them for mounting. The holes were placed over the small pegs to keep the bands in place. [Matt] used 3/4″ industrial elastic bands for this project. He then used a 120V 15W candelabra light bulb to illuminate the lamp. The final design is not only beautiful, but it can be flat packed and manufactured inexpensively.

If you want more inspiration for artistically designed lamps check out this one that uses the corrugation in cardboards as a shade pattern.

[via reddit]

Pool/Hot Tub Monitoring And Data Collection

June 1, 2015 by Rich Bremer 12 Comments

Pools and hot tubs, although enjoyable, require monitoring and maintenance to keep the water clean and clear. [bhuebner] didn’t like having to constantly testing his hot tub’s vitals using test strips and water test kits. In an effort to autonomously monitor his hot tub’s water, he came up with a project he’s calling SpaSitter that records and tracks water quality indicators.

The hardware is based on a Nanode (think Arduino with on-board Ethernet). Three sensors are connected to the Nanode and placed in his hot tub’s water. The sensors measure pH, ORP and Temperature. That data is then uploaded to xively.com where the data is not just stored, but tracked over time and displayed in graph-form. Checking the vitals on your phone can also get a bit tedious so [bhuebner] set up an email notification if one of the measured data streams go outside of a predetermined range. He still has to add chemicals manually and hopes to see some automation added to the next project revision.

[bhuebner] made his code available and also posted detailed instructions, including how to calibrate the sensors, for anyone wanting to do the same thing.