For those of you who have access to Harbor Freight and are engineers and techs who like to measure things, I strongly recommend the little Cen-Tech IR thermometer -- see the attached photo. It appears that Harbor Freight doesn't sell it anymore, but it was in my local Harbor Freight store for $10 for years. They have a $25 one that uses a laser for pointing, but I can do without the laser, as the one I have is 65 mm long by 35 mm wide by 15 mm thick. It nicely slides into a pocket.
I use this thing far more than I thought I would (I bought it about 4 years ago). For example, I've used it to find the hot component on a PC board. Right now I'm measuring the temperature rise of a wall wart at rated load inside a metal container and I just point and shoot. Of course, one needs to know the emissivity of the emitting surface to have an accurate measurement; this device uses a fixed emissivity of 0.95, which works fine for most things.
I would have loved to have this thing when I was working in industry, as it would have been so handy when working in the lab.
For more careful work, one first measures room temperature with e.g. an RTD, thermocouple, or thermistor. Then measure the device you're interested in after it's been sitting in the room a while. Then you can measure its temperature and correct for its emissivity and have good data. I don't bother doing this because I'm usually interested in temperature differences, but if I was, I'd do the correction by converting the temperatures to Kelvin, then calculating a multiplicative correction factor (because of the Stefan-Boltzmann radiation law). Then this can be used for further corrections. Of course, to be technically correct, you need to know that the emissivity doesn't change with temperature.
I use this thing far more than I thought I would (I bought it about 4 years ago). For example, I've used it to find the hot component on a PC board. Right now I'm measuring the temperature rise of a wall wart at rated load inside a metal container and I just point and shoot. Of course, one needs to know the emissivity of the emitting surface to have an accurate measurement; this device uses a fixed emissivity of 0.95, which works fine for most things.
I would have loved to have this thing when I was working in industry, as it would have been so handy when working in the lab.
For more careful work, one first measures room temperature with e.g. an RTD, thermocouple, or thermistor. Then measure the device you're interested in after it's been sitting in the room a while. Then you can measure its temperature and correct for its emissivity and have good data. I don't bother doing this because I'm usually interested in temperature differences, but if I was, I'd do the correction by converting the temperatures to Kelvin, then calculating a multiplicative correction factor (because of the Stefan-Boltzmann radiation law). Then this can be used for further corrections. Of course, to be technically correct, you need to know that the emissivity doesn't change with temperature.
