This week has been about learning the different types of temperature/light sensors available to us and the disadvantages and advantages of each type. As Molly experimented with one sensor, I set about wiring the circuit for the LM335A temperature sensor to the Arduino. However, I quickly learned that the Sparkfun Arduino book was written with a different temperature sensor in mind. They appear to have just replaced the name of another sensor (TMP36) with the the LM335A without changing the circuit. The LM335A and TMP36 are very different, the TMP36 not needing a resistor while the LM335A requires one, and the three pins do different things for each sensor. I researched the correct circuit configuration, but the numbers were always very off – freezing or boiling – therefore, it appears I was led into breaking the tiny $1.50 sensor. Live and learn, I suppose.
Next I was advised into researching thermocouples. These detect temperature differences using different metals to detect voltage. These are inexpensive and I was given an invitation to make one with a professor, but they are much too local for our needs. They wouldn’t be able to detect a candle until it was nearly to it, so they’re not practical.
I found a very popular sensor called the UVTron Flame Sesnor. It uses UV detection to find fires, even small ones like candles! It’s much more expensive than other sensors we’ve looked into, but it appears to be an excellent sensor for what we need. It also wouldn’t hurt to have more than one temperature/light sensor, as we want to cover different variables. Infrared sensors are usually expensive and things in the environment might interfere with them, but these little sensors can be bought in bulk cheaply, and if mounted all around the robot, can provide sensing detection at all angles.
Next, I will be working with Molly to try to get her LM335A working (without breaking it). I also found a light sensor made by the same company as the flame detector in Centenary’s physics lab, and may try to experiment with it, but I’m not sure if it’s sensitive enough. I’d also like to dissect some old childhood RC cars this week to study different wheel mounting techniques.