The one that is smoking is a to220 size, but just no heatsink.
How did you work out that the bulb has a resistance of 3ohm when fully lit?
What is that 15x15x8mohm calculation called, so I can look it up and study it a bit.
I am aware you can also calculate how much temperaure a heatsink will suck off the mosfet. But what size do I get 1" x 1" size?
Ahh, just had a look at it in a catalog and it says a degreeCelcius/W
example there is one here that is for a to-220, that is 19degree celcius/W (watt I assume)
How does this work then? It will suck away 19 degrees for every watt of power?
Then if I look at the much larger heatsinks they are rated at like 1.4degrees celcius/W, I know they will take the heat away better than the smaller ones but they have a lower temp/watt value???