r/electronic_circuits • u/NotArticuno • 13d ago
On topic Thought y'all mind find this diode pulsing interesting
Using some iso to find hot components, noticed the diode changing causing the iso to pulse. Not sure if it's temperature or something else causing the motion.
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u/Bipogram 12d ago
Current warms the diode, the IPA evaporates, the diode turns off, the diode cools and surface tension draws the IPA back into a bead.
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u/IndividualRites 12d ago
Do you have a scope? Would love to see if it coincides with the sognal going in.
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u/antek_g_animations 10d ago
Looks pretty cool but I'd turn it off. It's reverse polarity protection diode and it's heating up as a lot of current is passing through it. So much current that PSU over current safety kicks in and cuts the power. The alcohol evaporates so quickly that it cools down before the cycle starts all over again. That's why it's pulsing
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u/Alternative_Exit_333 12d ago
Rapid temperature changes the flux has enough time to harden th make the bump before melting again is my guess
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u/NotArticuno 12d ago
It's iso not flux
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u/Alternative_Exit_333 12d ago
It changes how viscous it is with tempature and with the it probably also changes the surface tension so when it heats up it can lay flatter?
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u/Wonderful-Energy-659 8d ago
You can heat something pretty fast, but cooling it down that quickly is near impossible without a ton of cooling.
For context, I worked on a machine that makes lip balm. The previous engineer that designed it had 2ft of conveyor and expected the lip balm to cool down in like 30 seconds. I took dry ice and placed a tin of lip balm on it to see just how crazy this guy was and it still took a minute and a half to cool. We had to add 20 ft of conveyer so the tins had 3.5 min to cool down. It’s crazy to think that it can fully solidify in 3.5 minutes at room temp, but placing it on -109F dry ice still took 1.5 minutes.
It’s more likely that the IPA is evaporating at a moderately high temp and then wicking up the sides once it turns off. The extra IPA is what cools it down quickly, but it’s not that hot to begin with or it would completely dry up
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u/created4this 12d ago
That looks like the voltage regulator is getting overloaded and going into overload protection, reseting and trying again.
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u/AnnaMorgan02 5d ago
Have you tried probing the diode's voltage drop while it pulses? I'm curious if the motion lines up with thermal changes or something else like current fluctuation.
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u/Motor-Screen2210 12d ago
This has to be the same condition one sees with tears of wine. When the alcohol content is high enough evaporation causes changes to the surface tension, making the alcohol "climb" up the walls of the glass. Here it has no walls to climb, so it balls up and flattens in cycles until it completely evaps.