Off the top of my head, mostly Modder's mods that use quality regulators like the OKR-T/6, PTR8100W, or PTN04050. The Lavatube v1.0 uses a filter, but it is horrible at maintaining the set voltage.
TBH, since China started calibrating for VRMS, there isn't much difference when you're talking about voltage (before ProVari fans get in an uproar...I'm only talking about the voltage, 4vRMS is the same as 4vDC no matter how you slice it).The new mods like the ZMax, Vamo, Volcano Lavatube 2.0, etc, etc, do a fine job of regulating accurate voltage. But if you are a high power vaper you'll need to stack 18350's to hold >11w over the entire battery life.
icould have sworn i read the chip they use was patented but i do know accuset is the trademark.
but from provapes website:
Our built-in dynamic self-calibration algorithm keeps the output voltage accurate to 1% or better over the life of the product. The ProVari will constantly monitor and adjust itself to ensure you always get accurate voltage settings. Every device will auto-tune itself so its always precise!
from an interview in spinfuell magazine: The AccuSet technology (created by ProVape) will constantly monitor voltage output, with accuracy to 1% or better over the life of the product.
Each ProVari will autotune itself so that your settings will always be accurate and worry-free.
while i agree to a point , fimd me another mod that is within 1% or less and will stay there for the whole charge.
This probably will get the Provari fans in an uproar....Creative Marketing.
Provape was certainly not the first to create an electronic device that delivers accurate voltage. This is the 21st century, every high tech device from cell phones to laptops, televisions, stereos, and even electric razors has a voltage converters. Many of them REQUIRE far more accuracy than a Provari; ripple currents less than 20mV. All of them need to constantly monitor the output and it is easily done with a feedback circuit to a comparator. Algorithms and auto-tune is just programming the processor to give the desired result. The Chinese mods use algorithms too, they're just not as refined.
Dont take this, or my post above, as a slight at the Provari. It does a great job of doing what it is designed to do. But in the end, it is a nothing more than a very expensive voltage converter. If you had an adapter you could screw an LED into it and have a mighty fine flashlight, or set it to 5v and use it to charge your cell phone, or to drive a small fan for hot summer days. Those that own a Provari paid a premium because it is a very well designed and well built voltage converter that does a wonderful job of providing voltage to a heating element.