This will be a long post. But, if you want to learn something by the end I promise you it will be worth it. So sit back and
I've seen a few post talking about how lights and coils react to PWM, most of it is wrong. A light bulb and a heating coil are essentialy the same thing. They both operate under the principal of converting energy to heat, this then causes the coil to glow giving off light. The only real difference between the two is intended use. PWM has been used to control the brightness of a light bulb for a longtime now, and probably has been known about even longer.
However, watching a light bulb controlled by PWM and how it is behaving to the PWM are two different things. If you take two of the same buld/coils, one has a constant feed of 60w, the other has a 50% duty cycle feeding it 120w they will appear to give off the same amount of light. In fact, the total measurement of lumens produced will be the same. Whats happening is that both bulbs produce the same measured amount of light/heat and use the same amount of total power. The 120w bulb is producing twice the amount of light/heat during it's on cycle and measured amounts average out at 60w. 120w on 50% / 0w off 50% vs just plain 60w.
The reason this is invalid is because it is missing one variable in this argument... Human perception.
Constant vision allows us to average out our visiual input. Our brains can even fill in the blanks when necessary. You do not see a bulb flickering on and off twice as bright as another. Our brain averages out the visual input by filling in the darkness with 50% of the on cycles total light output. The other 50% of the total light is seen as the bulbs on cycle. The end result is they look the same to us. However, the 120w bulb is producing twice the amount of heat/light during its on cycle.
If this is done too slow we can see the light turn off and back on. All of this must happen fast enough for our brains to be able to do this at a certain number of hz, or times per second. Here is the real kicker to this, that number is... approximately 30hz. That 33.3hz number did not come out of the blue during design, it is there for a reason. It is just on the other side of 30hz so we can not see the heating coil visibly flicker.
So now the real problem is... The PWM coil is heating up hotter in the same amount of given time because it is being pushed harder. The problem is not averaging out heat it is the transfer of heat to the eliquid and that this process happens so fast the eliquid never gets a chance to coil to ambient temperature. Over a measured amount of time the juice with end up hotter then with a flat signal output. During this time the tempt of the juice is also going to fluctuate as the heating coil changes between the on and off state..... THIS LADIES AND GENTLEMEN IS THE REASON THAT THE PROVARI AND MECH MODS VAPE BETTER THEN THE 33.3hz DEVICES!