Heatsinking through hole resistors?

[tszaboo]

Heres a variable high wattage resistor with built in heat sink. Caution it gets really hot.

It is also a PTC, with very interesting characteristics.
It gets open circuit when it reaches a certain temperature.

[Simon]

They are often used as heaters with their intentional self limiting characteristics for safety

[bd139]

Incidentally on this as I cocked up recently when I built a dummy load, watch out for TH resistors - they can actually desolder themselves if you overload them a little bit. Make sure there is a rigid mechanical mount as well as the solder one. I opened my dummy load to find that the entire thing had disintegrated

[Karlo_Moharic]

There are this things called POWER RESISTOR , they look something like this: https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xpower+resistor.TRS0&_nkw=power+resistor&_sacat=0

[KL27x]

Some power resistors have a heatsink on them. But in general, you don't often find a scenario where you want to put a heatsink on a resistor. 

As opposed to a semiconductor, a resistor
1. Has an increasing resistance with temperature, so it is somewhat self-limiting. There is no point of thermal runaway.
2. Can operate at a much higher temperature. The higher the temp differential to ambient, the greater the heat transfer to surrounding air. This means you don't get as much benefit out of a heatsink. If semiconductors could operate at 150C with no decrease in performance, you would rarely need to use heatsink for IC, either. (A resistor changes resistance, which is a change in spec but not a decrease in performance, per se... I.e., you could use a different resistor to get the resistance you need at 150C )

Bottom line, it is usually more efficient (space and $$) to just use more and/or larger resistors than to add heatsinking to a resistor.

[T3sl4co1l]

You must have shitty resistors if they're going out of tolerance at 150C.   (At a glance, NiCr is up by 5% at around 800C?)

Speaking of semiconductors, it's too bad that we have SiC and GaN power transistors nowadays, yet we still don't have anything that can do better than 175C in commercial product lines.  Semis are limited by packaging more than by material.   (200-300C parts are available, but they're ceramic and gold military packages, $100 and up sort of thing.)

Tim

[GigaJoe]

Had I rush to make some load:
It dissipated almost 7W; Realize if wire will be longer, more surface, can pump more

[KL27x]

^ When I need higher wattage and don't want a burn/fire hazard, I use a piece of copper clad and cut some lines in it and solder w/e value of resistors I have that will give me the right resistance and power rating in parallel... or mix of series/parallel as needed.

Nichrome wire and a pair of alligator clips will up the fun factor for quick testing.

[Zero999]

Heres a variable high wattage resistor with built in heat sink. Caution it gets really hot.

It is also a PTC, with very interesting characteristics.
It gets open circuit when it reaches a certain temperature.

Yes, it's not really a variable resistor either. Adjusting the dial doesn't vary the resistance. All it does it change the temperature, when the thermostat disconnects the power.