@DirkBongo (don't know how to reply with a quote)
You said it all...a fast car with no brakes!!! I wish I'd have thought of that.
You said it all...a fast car with no brakes!!! I wish I'd have thought of that.
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actually its not the case at all, a provari is a switch mode.
go and look at pwm and switch modes on wiki, the only similarity is that both use a duty cycle, a switch mode converts electrical energy into a magnetic field then back to electrical again. pwm has no magnetics and can not boost at all.
Why people use LR stuff on a powerful device like the VMax is beyond me. Get some 3.0 ohm single coil or 2.0-2.5 ohm dual coils for it so you can actually use the PV for what it was made for and quit complaining "oh this thing hit's way too hard and burns everything". K thanks 
Never thought I would hear people complaining about a PV hitting too hard. Looks like it would be the other way around lol.
BTW the "too" high PWM voltage spikes have been tuned down in the newest versions and vapes like a champ.
Never thought I would hear people complaining about a PV hitting too hard. Looks like it would be the other way around lol.
BTW the "too" high PWM voltage spikes have been tuned down in the newest versions and vapes like a champ.
Why people use LR stuff on a powerful device like the VMax is beyond me. Get some 3.0 ohm single coil or 2.0-2.5 ohm dual coils for it so you can actually use the PV for what it was made for and quit complaining "oh this thing hit's way too hard and burns everything". K thanks
Why have a 5amp limit?
The amp limit does nothing other than allowing you to vape lower ohm carts or atty's and it was actually a selling point of the device. Generally, if you want your device to "hit hard" then you use a higher voltage - the user should be the one that decides this, not the device.
3 volts is still 3.7 volts on the newer versions.
I think Phil's point is not that it's what PWM devices do, but rather what badly calibrated PWM devices do.
Yes that was his point. But, he was reviewing the V1 Vmax, and, I don't care how much people love him, he is not an electrical engineer or a brilliant mathematician as far as I know.
There is a formula to figure out average voltage output on a PWM device. It is not something as simple as hooking it up to a basic scope and reading the numbers. Now I guess someone has gone through the hard math to come up with the 3.0=3.7 that Dirk posted, I would love to see the numbers BTW, and if the calculations are correct, then it is way off.
One of the problems is the implementation of PWM on this, and other devices as well, is not like the way it is used other devices, such as the Provari. So you have a large group of Provari fans who, even though the output method is quite different, assume that their (or any other) device is right and dead on, without taking into account the design differences.
I am not saying the Vmax is right, or even close, but I am saying until someone shows the hard, properly calculated, numbers to me, then I will chalk it all up to differences of opinion and/or output method. And yes Optimo, I never thought I would see it either. I loved my Vmax(s), until they failed. And I am upset that I will probably never own another.
Salky
Well. I've had a Provari on a scope and it puts out pretty clean DC with a very gentle ripple.
The average voltage of a non-sinusoidal wave doesn't necessarily equate to accurate wattage calculation against a load. Some non-sinusoidal waves might calculate correctly, assuming a particular waveform and duty cycle. But there's also physics involved in how heat energy bleeds off the nichrome coil.
Here's some of my research....
Example:
Wattage Formula with DC numbers as an example:
W = (V*V) / R
Let's assume 3.0 ohms at 4.1 volts:
(4.1 * 4.1) / 3.0 = 5.60
Wattage: 5.60
Wattage formula with PWM as an example with "D" being the duty cycle:
W = ((V*V) / R) * D (Duty cycle)
Let's assume 3.0 ohms at 8.2 volts with a duty cycle of 100%.
((8.2 * 8.2) / 3) * 1 = 22.41
Wattage: 22.41
So let's say the duty cycle (D) is 50%. That is to say that the average voltage will be 4.1 volts.
(8.2v + 0v) * .50 = 4.1 right? I should be getting 5.60 watts right? Nope:
((8.2 * 8.2) / 3) * .50 = 11.20
Wattage: 11.20
But wait... the average voltage is 4.1 right? Right. But the wattage isn't 5.6. Right.
So that is the first problem in concept with PWM mods. The second is the duty cycle. This also illustrates *why* Evolv calibrates in watts rather than volts... it's a much *finer* adjustment in regard to the real power applied.
So lets say just for fun that the length of the duty cycle needs to be shortened to get down to our 5.6 watt goal.
40 percent duty cycle (power active 40% of the time):
((8.2 * 8.2) / 3) * .40 = 8.96 watts
((8.2 * 8.2) / 3) * .30 = 6.7 watts
((8.2 * 8.2) / 3) * .25 = 5.6 watts
So there's an example of power regulation based on duty cycle.
But... it's not really correct. And this has to do with physics.... and tell us why a vmax "hits harder".....
Let's assume the circuit in our regulated ecig is running these current values:
((8.2 * 8.2) / 3) * .25 = 5.6 watts
Why does it hit like .5v to 1.v DC higher against a 3 ohm load?
Answer: because for 25% of the time that circuit is active at 22.41 watts. That is huge energy compared to 5.6 watts continuously. The coil on the atomizer is essentially vaping at 22.41 watts for the duration of the powered cycle. That means you are getting a mouth full of 22.41 watt vape, followed by a decreasing vape, followed by a 22.41 watt vape...
See what I mean? The coil doesn't bleed off energy (in the form of heat) as fast as the energy is applied (even at 5.6 watts DC). But, because the energy is so great at 22.41 watts- you perceive a harder hit.
As near as I can tell- this is why 3.0 volts on a vmax hits so hard. I'm happy to accept corrections where appropriate.
20W for a quarter of the time will feel EXACTLY the same as 5W continuous.
pwm figures are not hard to work out at all.
any wattage is v^2 /R where v is rms, with a pwm mod you use the peak voltage and multiply by the duty cycle.
Pout = ( Vpeak^2 / R ) * duty
having a mod that hits too hard is stupid unless you want to use HV attys, i want to use ego C attys. they are fine up to 4v .. vmax minimum is about 4.5v rms.
not sure how readable the picture is yet, my home made meter does RMS .. thats 4.5v. when the vmax is set to 3.0, the multimeter is reading the average 2.8v
ah, i will photobucket the pic, then you can read the figures on the CRO as well.
pwm figures are not hard to work out at all.
any wattage is v^2 /R where v is rms, with a pwm mod you use the peak voltage and multiply by the duty cycle.
Pout = ( Vpeak^2 / R ) * duty
having a mod that hits too hard is stupid unless you want to use HV attys, i want to use ego C attys. they are fine up to 4v .. vmax minimum is about 4.5v rms.
not sure how readable the picture is yet, my home made meter does RMS .. thats 4.5v. when the vmax is set to 3.0, the multimeter is reading the average 2.8v
ah, i will photobucket the pic, then you can read the figures on the CRO as well.
Attachments
*shrug*
I tried. But I think your missing the point of the physics at the end. The coil has to get rid of that energy. And given the issues with wicking, it;s going to get rid of that energy a lot slower than it's being applied.
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not sure how readable the picture is yet, my home made meter does RMS .. thats 4.5v. when the vmax is set to 3.0, the multimeter is reading the average 2.8v
You're the one making those meters.
They look fantastic, I'll have to buy one from you at some point.
Hi,
First of all great accurate explanations of the "mystery".
I have a Vmax V2 (SS, "smart display") and one thing i tried out was releasing the button for the last third part of my vape. This cools down the coil and reduces the excessive heat, so no dry burn or odd taste. This works for the most of the time but if i forget the next vape is just horrible. Other thing i noticed that when the batteries are starting to deplete the vape is much smoother, not so hard hitting. Maybe there is a way to increase the resistance before the current hits the resistence???
I think the problem is in a too high start voltage if we can reduce this then it would be perfect. I know that the V1 was worse and as it seems the V2 is used in the V3 and V4, so nothing new there.
Using at this moment 2 VIVI Novas with 2,6-3,0 Ohms (no accurate reading due to temperatures) and "learned" from all you guys.
Hope this gives you some ideas.
First of all great accurate explanations of the "mystery".
I have a Vmax V2 (SS, "smart display") and one thing i tried out was releasing the button for the last third part of my vape. This cools down the coil and reduces the excessive heat, so no dry burn or odd taste. This works for the most of the time but if i forget the next vape is just horrible. Other thing i noticed that when the batteries are starting to deplete the vape is much smoother, not so hard hitting. Maybe there is a way to increase the resistance before the current hits the resistence???
I think the problem is in a too high start voltage if we can reduce this then it would be perfect. I know that the V1 was worse and as it seems the V2 is used in the V3 and V4, so nothing new there.
Using at this moment 2 VIVI Novas with 2,6-3,0 Ohms (no accurate reading due to temperatures) and "learned" from all you guys.
Hope this gives you some ideas.
I have a pretty good grasp on physics actually.
heat is energy, energy is joules ..
ok, the amount the coil will heat up to is based on how many joules per second are fed into it and how many joules per second it can lose. the temperature at which these match is the temperature it will maintain.
now .. not coincidentally, 1 joule per second is one watt.
so 4 times the power for 1/4 the time is the same amount of energy, themal mass ensures that the temperature fluctuations are not too extreme, a vmax works at close to 1khz so there is very little time for the temperature to change much.
cheers, 3 left in this batch then a 3 week wait for parts, i have a thread on vapor wall currently.
Yeah, saw it on Vaporwall yesterday (and on Ebay) but as usual the only thing I have in my pocket is lint.
Glad you'll be making more because I'll get one from you when my finances improve.
I'd say that's all firmware based and not something anyone could doing anything about except the manufacturer.
To vape duals or tripples, maybe even quads lol. If I want my VMax to hit harder I do raise the voltage...dunno what you're talking about tbh. On the R4 3 volts feels like 3 volts to me 4 volts feels like 4 volts and so on. You musta just used the ones with that 8.4 PWM spike issue.
Anyways, I take short 3-4 sec hits and love anything over 10 watts...I guess the VMax isn't for people that like cold 10 sec drags at low voltage.
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Optimo,
You know I've had six Vmax's - 1 V1 and the rest were V2's which as far as I know, had the same PWM as the V3 and V4.
Sounds like you've "vaporized" your taste buds with all that V1 Vmax action.
Sometimes I take "cold 10 second drags at low voltage" but not a lot.
At least I have a choice in the matter
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Optimo,
You know I've had six Vmax's - 1 V1 and the rest were V2's which as far as I know, had the same PWM as the V3 and V4.
Sounds like you've "vaporized" your taste buds with all that V1 Vmax action.
Sometimes I take "cold 10 second drags at low voltage" but not a lot.
At least I have a choice in the matter
I guess it's where I never vape cartos or anything of the sorts...I dripped with standard attys for years and now all I use is 3 different Phoenix RBA's. Right now I have a single 2.4 ohm coil running at 5.4 volts and it vapes like none other. With a SS mesh wick it tastes like pure heaven. I just find that with standard or HR stuff you have more play in the voltage settings/wattage. If you use LR it pretty much defeats the purpose of the VMax.
Optimo,
You know I've had six Vmax's - 1 V1 and the rest were V2's which as far as I know, had the same PWM as the V3 and V4.
Sounds like you've "vaporized" your taste buds with all that V1 Vmax action.
Sometimes I take "cold 10 second drags at low voltage" but not a lot.
At least I have a choice in the matter
Wow 6? Sounds like people should stop worrying about how hard it hits and try to figure out why they are such junk!
BTW, the only point I feel the VMax may have been off was at lower voltages with LR equipment. When running anything around 3ohms I tended to set the Vmax at the same spot I set the Provari, give or take a hair. And I felt the Vmax, right or wrong, did a better job on 4-5ohm devices altogether.
But my Provari is still alive, and that is the only advantage, give it a HUGE one, I give it over the Vmax.
Maybe Smok should just eliminate the number system and come up with a pretty color scheme to determine output level. I'm guessing most people could really care less about the number and would just be happy when they find their sweet spot. Plus it would drive all the internet electrical experts out of their minds! (Not referring to anyone in particular with that comment, you know what I am talking about)
I don't use LR.
As evidenced by some of the earlier posts in this thread, folks are having issues with SR on the Vmax too.
The duty cycle on lower settings is putting out fairly high voltage long enough to effect the temperature of the vape, it's not a "perceived" effect either - it's a physical effect.
If I set my device at 3 volts then I like it to feel like 3 volts and the same for 5 or 6 volts.
I think that's a fair and reasonable requirement.
My biggest issue with the Vmax was reliability and having three units go south on me - I'm just trying to stay off the smokes and I don't need the hassle.
As evidenced by some of the earlier posts in this thread, folks are having issues with SR on the Vmax too.
The duty cycle on lower settings is putting out fairly high voltage long enough to effect the temperature of the vape, it's not a "perceived" effect either - it's a physical effect.
If I set my device at 3 volts then I like it to feel like 3 volts and the same for 5 or 6 volts.
I think that's a fair and reasonable requirement.
My biggest issue with the Vmax was reliability and having three units go south on me - I'm just trying to stay off the smokes and I don't need the hassle.
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