Electronics > Beginners
Using a small resistor in some water instead of a power resistor?
help_me_pick_username:
I don't have any large power resistors, I was wondering whether I could, instead of a power resistor, use a 1/4w resistor dunked in some water to dissipate some power? If this was even remotely possible, how much power would I be able to dissipate?
Siwastaja:
You need to try it out, and it will heavily depend on the construction of the particular resistor you have, but I'd expect anything between just 1W and maybe even 5-10W.
If the voltage is very low (say < 1V) and the operation is short, electrolysis and corrosion isn't a problem. For higher voltages or permanent solutions, you need to properly coat it, and any coating will cause significant penalty in heat transfer; all epoxies and plastic-based materials have poor thermal conductivity. If the internal temperature rises too much, the coating material may be damaged slowly, finally letting water into contact with the leads.
For a properly epoxy coated solution, the end result may not be too stunning. It may be good for only, say, 0.5W, in the end, due to the excess thermal resistance added by the coating.
AVGresponding:
You'd be better off using either auto coolant or mineral oil, but unless you have a flow it'll not help much, and ultimately the surface area of the resistor will still limit the maximum dissipation quite badly.
Even with good flow, to a radiator, you probably aren't going to get better than 5x rated power.
Unless you're happy to see the coolant boil ofc... :-DD
Edit: This sounds like a fun experiment!
mikeselectricstuff:
RoGeorge:
OK, but careful not to kick the bucket! :)
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