Electronics > Beginners
finding harvested resistors power rating
T3sl4co1l:
Point-and-shoot thermometers have a fairly large spot size, and a focal distance. The most common usage error I see, is not understanding that the sensor line-of-sight is parallel to the laser sight -- offset by a fixed distance. You have to aim above the target to measure it. This is easy to demonstrate, but many people don't think to test their instruments but take them at face value instead, and will never discover this.
Tim
rsjsouza:
--- Quote from: wraper on November 29, 2019, 12:32:15 pm ---
--- Quote from: rsjsouza on November 29, 2019, 10:10:51 am ---
--- Quote from: wraper on November 29, 2019, 09:38:26 am ---
--- Quote from: rsjsouza on November 27, 2019, 03:35:20 pm ---Yes, anything near 60°C is already quite unbearable to touch. That is why I tend to have at least one cheap DMM with temperature around both my work and my home lab.
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And it's basically useless for measuring resistor temperature unless you will attach thermocouple with thermally conductive compound. And even then nearly useless for small resistors because thermocouple itself will sink a lot of heat. I feel like facepalming every time when someone touches heatsink or some part with junction on thermocouple end and thinks he is measuring it's temperature.
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Imprecise? Yes. Useless? Hardly.
It surely beats the finger test.
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If you measure something like half of actual temperature, I call it useless.
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--- Quote from: rsjsouza on November 29, 2019, 10:10:51 am ---It surely beats the finger test.
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Take a chill pill, dude. The OP's resistors have significant mass when compared to a sensor. SMD resistors, sure.
wraper:
--- Quote from: ThickPhilM on November 29, 2019, 05:23:21 pm ---They do work, you just have to be mindful of the limitations, and adjust your measuring technique accordingly.
Full on thermal camera time is for the birds, and those with cash to burn. Even used (and useful) gear is well beyond the means of most hobbyists.
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You can try as hard as you can but you will get much lower reading than actual resistor temperature (given that resistor is hotter than background). You will mostly measure background, not actual resistor.
magic:
Measuring small things with cheap IR guns is bonkers, the measurement area is easily 1cm across or more even up close.
I haven't verified but I suspect that those things don't even focus at all and the sensor is placed closer than one focal length behind the lens for an infinitely diverging "field of view". Anyone knows?
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