Raspberry Pi automates your tomato farm

rpi-tomato-farming

Check out the tomato plants [Devon] grew using a monitoring system he built himself. It’s based around a Raspberry Pi. As far as grow controllers go it falls a bit short of full automation. That’s because the only thing it can actuate is the black water line seen hovering above the plants. But [Devon's] work on monitoring and collecting sensor data should make it easy to add features in the future.

The moisture sensors pictured above monitor the soil in which the plants are growing. But he also has temperature and light sensors. These are very important when growing from seed and could be used in conjunction with a heating mat for plants that require higher soil temperatures (like pepper plants). The tomatoes are also pretty leggy. Now that he’s monitoring light levels it would be good to augment the setup with a grow light. A long term goal could even be a motorized bed which could raise the plants right up to the bulbs so they don’t reach for the light.

Don’t let the stars in our eyes distract you though. He’s done a ton of work on the project both with the physical build, and in plotting the data collected by the system. Great job!

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Analog soil moisture alarm

The lion’s share of soil moisture monitors we see are meant as add-ons for a microcontroller. So we’re glad that [Miceuz] tipped us off about this soil moisture alarm he built with analog parts. It’s really not hard to take the concept and build it in the analog world. That’s because you’re just measuring a resistance value. But for those of us who never really got started with analog parts this is a great project to learn from.

A high-efficiency op-amp is doing the brunt of the work. When the soil is moist the resistance is rather low compared to a reference voltage provided by a separate resistive divider. But when the plant gets thirsty and the soil dries out the resistance increases, triggering the op-amp to illuminate an LED and create some noise on the buzzer (we’re a bit confused on how that buzzer works).

Unfortunately this isn’t a viable long-term solution as the battery calculations show it lasting only about four months. That’s where a microcontroller-based circuit really shines, as it can put it self in low-power sleep and wake infrequently to take readings.

Tears from your lonely heart will activate a comforting tune

If you’re forever alone we’d guess you’ve long since stopped crying about it. But if you’re still prone to shed a tear on a dateless Valentine’s day this project’s for you. [Mikeasaurus] spruced up this pillow to play a tune when it senses your lonely soul. It’s got a moisture sensor which triggers an audio greeting card just when your weeping really starts to get soggy.

If you look closely at the top portion of the white fabric in the picture you can see there are rows of stitching. These hold a matrix of conductive wire mesh fabric on the inside of the pillow case. There are two buses made up of alternating rows (think of the tines of two forks pointed together) which make up the probes. When the gap is bridged by moisture a transistor circuit triggers the audio bits from a greeting card to play a song. Check out the demo after the break. We’re not satisfied that [Mikeasaurs'] couldn’t even bring himself to cry real tears for the clip, but maybe years of solder fumes have clogged up those tear ducts.

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