I’ve researched what type of cheap current and temperature sensors I would like to prototype for my project and decided upon the following:
1. An NTC Type Thermistor from Cantherm (CWF1B104J3950) that provides relatively high precision, reliability, and response time. This type of sensor also allows for a fairly simple conditioning circuit.
2. An Integrated-circuit precision temperature sensor (LM34) from National Semiconductor. This sensor provides a very linear output (+10mv/°F scale) at a very low cost. The problem with the IC type sensor is that it requires a more complicated power supply if you wish to measure temperatures around or below 0° Fahrenheit. I’m prototyping these since I already have a decent supply of them.
3. The CR Magnetics’ CR8410 current-sensing transformer. This a relatively cheap current transformer that is capable of measuring up to 20 amps. You need to take precautions when using this type of device since there is a potential to create high voltages when reading house current so if you aren’t sure, get someone who is experienced with these.
These parts were ordered from Digikey. I use both Jameco and Digikey when buying electronic components and I’ve always had good results with both companies.
Also, some thanks to the people over at All About Circuits, I wasn’t sure on the transformers and they were there to help me out.
When they arrive, I’ll set these components up to do some initial testing and evaluation. In the meantime, I’ll start some initial work on the Computer measurements I discussed earlier as well as a solution for converting the conditioned signals from the current and temperature sensors to a digital signal a computer can understand.
