The permeability of the core material goes all to hell at both high and low temperatures. Also, insulation melts at high temperature (RoHS was a RPITA for a while). Lower inductance can cause switching regulators to get really pissed (current goes to infinity as inductance goes to zero).
Inductance doesn't go to zero. Air-cored coils still have some inductance.
Core materials do have a Curie point temperature (Marie Curie's husband) and if they get hotter than that they stop being ferromagnetic.
Cooling has less dramatic effect.
Now is that 40 C or F ! Be specific ! (LOL)
Actually whatever you need to work at 50C is probably more extreme than wha t would need to be looked at here. A regular food freezer can do 0F, we ar e at what, about -18C ? That makes me want to just stick a cap in an ice cu be tray and measure it right when it comes out. Once the ice starts to melt I know it is at 0C. I think I have a freezer thermometer around here somew here.
What would be nice, though I am not sure about how useful, would be to isol ate the ESR component from the capacitive drop component at the lower tempe ratures. they would affect the circuit, especially a regulation loop a bit differently.
Sounds like an interesting thing to so just for the hell of it.
Actually with your freezer at work you can do it with an ice cube anyway, t hough it may have to be big for a bigger cap. It would hold its temperatur e long enough to get a reading because of the thermal mass of the H2O. How long does it take to measure ESR and capacitance ? Then if you want, with a thermometer you could plot it as it slowly comes up to ambient. You would have plenty of time.
I don't know how much lower I could go than 0F. My freezers are set COLD, b ut they are newer ones and won't do -25F like some of the old overpowered m onstrosities of the past. Plus they are full so it would take forever to ge t them to change.
AHA, I just notice me old thermometer, goes down to -60F. I just stuck it i n a freezer to see what it reads. Tomorrow I should know.
Wrong.
Wrong.
AlwaysWrong.
We had a regular chest freezer we used for a while. Disabling the thermostat and adding dry ice too it would go to ALMOST -40 ! About
-37C. Right in that it doesn't really need to be measured to less than -40 per usual specifications BUT we have had a customer in Alaska that would prefer the units to run down to -50C I think he said. Fairbanks area.
Just for the hell of it would be correct
Have something to add? Share your thoughts — no account required.
Ask the community — no account required