whats the difference between a .20 coil and a .50? Also, does an rx200 have temp control? Like if it gets overheated or hot will it still let me hit it?
difference in a 0.20 and a 0.50 is the amount of wire (ie: length of wire) in that prebuilt coil
I'm a bit confused on your Temp Control (TC) question.
If you're asking if the mod itself has temperature control function that regulates your coils then yes, but this is only possible under Temperature Control mode. In regular power mode the rx200 will keep on channeling power into your coils with no upper threshold limit (until the fire timer kicks in which is usually 10-12secs).
If you're asking about battery / chip safety where the RX200 will cut power when its internal temperature gets too high then yes, I believe it has that function as a failsafe for battery failure.
[edit] just wanted to add to the ohms question
In a nutshell, resistance measured in ohms depends on really just 2 things
1. Distance - ie: total wire length, which usually means how many wraps - longer the distance, higher the resistance and vice versa.
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2. Wire gauge - ie: thickness of wire for current to pass - thinner the wire higher the resistance and vice versa.