Plant’m If You Got’m And Keep’m Alive

Having a few plants around is a great way to liven up your living and/or working space. They look nice, you get to watch them grow and change, and some types of plants can actively improve the room’s air quality. But let’s face it — even the easy ones require a baseline level of care that can easily fall by the wayside. After all, the poor things can’t scream out for water or get up and find a sunnier spot for themselves.

[Ine Hocedez] was tired of watching her plants die and not knowing why. The two main culprits involve water and light, though there can be other issues like soil pH and bugs. It’s easy to get the balance wrong, so why not automate everything?

Plant’m is a complete, portable package that [Ine] designed for a school project. A soil moisture sensor dictates the watering schedule via Raspberry Pi, and water is automatically pumped from an elevated tank.

The lamp is meant to supplement the sunlight, not replace it. But that’s the real beauty of this botanical box — [Ine] can just pick it up and try a different spot if the plant droops or shows burnt spots.

Got the sunlight part down for your plant, but can’t remember to water it? Re-purpose an old Keurig and give it an automatic drip.

Logging Engine Temperature For RC Models

[Rui] enjoys his remote-controlled helicopter hobby and he was looking for a way to better track the temperature of the helicopter’s engine. According to [Rui], engine temperature can affect the performance of the craft, as well as the longevity and durability of the engine. He ended up building his own temperature logger from scratch.

The data logger runs from a PIC 16F88 microcontroller mounted to a circuit board. The PIC reads temperature data from a LM35 temperature sensor. This device can detect temperatures up to 140 degrees Celsius. The temperature sensor is mounted to the engine using Arctic Alumina Silver paste. The paste acts as a glue, holding the sensor in place. The circuit also contains a Microchip 24LC512 EEPROM separated into four blocks. This allows [Rui] to easily make four separate data recordings. His data logger can record up to 15 minutes of data per memory block at two samples per second.

Three buttons on the circuit allow for control over the memory. One button selects which of the four memory banks are being accessed. A second button changes modes between reading, writing, and erasing. The third button actually starts or stops the reading or writing action. The board contains an RS232 port to read the data onto a computer. The circuit is powered via two AA batteries. Combined, these batteries don’t put out the full 5V required for the circuit. [Rui] included a DC-DC converter in order to boost the voltage up high enough.

Over-engineering A Two-zone Thermometer

We love the extra touches that [Andrianakis Haris] added to his two-zone electronic thermometer. It includes features that you just wouldn’t find on a mass-market commercial product because of issues like added cost. For example, you can see that the PCB juts up above the LCD display, allowing the module to be mounted on a pair of screws thanks to the keyhole shape that was drilled in the substrate. I increases the board size greatly, but on a small hobby run this won’t usually affect the price of the board depending on the fab house pricing model.

The design uses an ATmega8 microcontroller to monitor sensors in two different places. There is an onboard LM35 temperature sensor for monitoring the space where the unit resides. A remote sensor module uses a DHT-11 chip to gather data about temperature and humidity. That sensor is wired, but there is one wireless option for the device. Data can be pulled down from it via an optional Bluetooth module which can be soldered to a footprint on the back of the board.

Check out the video after the break to see temperature readings pulled down wirelessly. Continue reading “Over-engineering A Two-zone Thermometer”