02 November, 2011

Great Astrophotography - A How-To Guide

Many of us have looked up into the night sky in a particularly dark place and thought, "This is incredible!  I really wish I could take a picture!" or we've seen others' photos of the stars and the Milky Way and wondered how on earth they got such incredible images.  As it turns out, it really isn't as hard as you might think.  This guide will teach you how to plan your shoot like a pro.

A prime example: proper use of foreground elements by a master
of astrophotography, Brad Goldpaint.


05 October, 2011

Agricultural Sensors - Part 3: Source Code

Read Agricultural Sensors - Part 2: Digital

Blogging generally isn't the best format for distributing code, but here it is.  I'll try to find a home for the source code in a downloadable file later.  The code comments, as well as the previous two blog posts should explain the concepts here.




/*
 * GardenSensor v0.4a
 * 
 * Reads three 10k Ohm thermistors for ambient, soil, and shade temperature
 * Reads one 1M Ohm CdS photocell for ambient light between 500-700nM
 * Reads one IR LED as a sensor for ~ 950nM infrared radiation levels

Agricultural Sensors - Part 2: Digital

Read Agricultural Sensors - Part 1: Analog

OK, in the last entry I mentioned that we can use LEDs as light sensors.  I will elaborate on this before I continue writing about the rest of the Agricultural Sensors for Arduino device.  LEDs are diodes, they only allow current flow in one direction.  Normally, you allow current to flow across the LED, and photons are emitted.  For our purposes, we will be reversing the polarity of the LED, and measuring its resistance via the Arduino Uno analog input pins.

Agricultural Sensors - Part 1: Analog



  AgSensors is an Open Source and Open Hardware project which uses extremely inexpensive equipment to gather reliable and valuable data about solar, thermal, and soil conditions.  Novel concepts such as simple spectrography by using LEDs (yes, LEDs as sensors will be explained in detail) and handmade soil probes controlled by an Arduino Uno.  In an effort to learn more about wireless sensor networks and programming in general, I've begun work on a project which allows capture of agriculturally significant data.