Variable Voltage mods and pulse width modulation

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cozzicon

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PWM is a good way to regulate voltage. Filtering the output produces a similarity of straight DC with some ripple that would be visible on a scope, but it will view on a cheap DVM as average voltage.

To an atomizer coil, PWM or straight DC is really a non-issue. What matters is consistent heat on a coil produced by voltage across a resistance. It's aggravating that we can't use our $15 inline DVM to read them, but a regular averaging voltmeter will do it. You just have to have an adapter tube with test points for the probes.

PWM is a good thing. It's an inexpensive, but effective way to regulate voltage in a small package. My Provari output is filtered and reads exactly on my cheapo DVM with the 510 connections on each end. My eGo just flashes the readout because it's not filtered. My Boge carto doesn't care. It just wants to see an average voltage. Each pulse produces some heat on the coil and the next pulse maintains it. A capacitor across the output would make it read on the inline DVM by storing the voltage until the next pulse comes along.

Dave, I'm not arguing that point. Trust me.

It's when they regulate by *length of duty cycle* where PWM fails- or at least has had some bad programming on the vmax and another mod I've been working with.

In those cases, the voltage displayed was not commensurate with the wattage output. That's an issue for low watt vapers who go regulated for *consistency*.
 

DaveP

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Dave, I'm not arguing that point. Trust me.

It's when they regulate by *length of duty cycle* where PWM fails- or at least has had some bad programming on the vmax and another mod I've been working with.

In those cases, the voltage displayed was not commensurate with the wattage output. That's an issue for low watt vapers who go regulated for *consistency*.

I agree that PWM isn't implemented well on some devices and there are others that can't supply the current needed for the load. I don't have access to a scope anymore to test waveforms and vendors don't supply pulse frequency information or scope shots.

Bottom line is the inline voltage test on a 1.5 ohm atty. If it maintains advertised voltage under load throughout its range, it's a good one. ;)

BTW, I value your opinions highly, Cozz!
 

gordong11

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I think its safe to say that most PWM devices out there fall short of being desirable. It's seems like a shortcut to me. My Innokin iTaste does not have PWM and is under $70. If I was a factory and going to use PWM, I'd make sure it was done right, it can't cost much more.

Why waste the money and risk it when there are good devices out there at reasonable prices to do not use PWM, or implement it right? I am not sure I want my $25 1.5ohm HH357 atty being hit with 6.0v pulses, I don't care how quick the PWM is.

Added: Until PWM is figured out, I don't want it no matter how good its done and It's impossible to tell unless purchased. It's one of those things where the theory is sound, but doesn't work in real world usage for whatever many reasons. IF I was a 5v-6v vaper I wouldn't care about PWM, but that that is just another reason why I don't like it, its not good across the board for all vapers.
 
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yzer

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The biggest problem with PWM in APVs is at the lower voltage/wattage levels. That's where there seems to be the largest disparity between PWM and non-PWM performance. Pbusardo points out that 3.7V on a couple of Smoktech devises perform more like 4.2 or 4.5V without PWM. Unfortunately, this means you really can't do LR vaping on these devices.

Voltage regulation does not necessarily mean PWM. My Smoktech E-Power 14650 is voltage regulated at 3.7V. I can read the output voltage on a standard DMM, so it's not PWM.

PWM has been around quite a while in many applications. It's faily new in APVs. The solar charge controller I installed on the boat uses PWM to maximize battery charging efficiency.
 

DaveP

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The biggest problem with PWM in APVs is at the lower voltage/wattage levels. That's where there seems to be the largest disparity between PWM and non-PWM performance. Pbusardo points out that 3.7V on a couple of Smoktech devises perform more like 4.2 or 4.5V without PWM. Unfortunately, this means you really can't do LR vaping on these devices.

Voltage regulation does not necessarily mean PWM. My Smoktech E-Power 14650 is voltage regulated at 3.7V. I can read the output voltage on a standard DMM, so it's not PWM.

PWM has been around quite a while in many applications. It's faily new in APVs. The solar charge controller I installed on the boat uses PWM to maximize battery charging efficiency.

I can read the output of my PWM eGo batteries on my DMM. It's the inline DVM with 510 jacks on each end that flashes 888. It doesn't have averaging circuitry and filtering to handle PWM. Most handheld DMMs are averaging voltmeters.
 
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DaveP

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So the provari doesnt use PWM correct? Whatever it uses I'm extremely happy with it.

What about the kick? It works great in my SB.

Pardon my electronic ignorance.

Provari is a PWM device. It's just done well with filtering added. It reads accurately on my inline DVM module.

From Provape's FAQ. Frequently Asked Questions

Does the ProVari use PWM? (pulse-width modulation)

Yes, the ProVari is using PWM technology

Everything with a switching power supply uses PWM these days. That does away with step down and step up transformers to convert voltages. It makes VV ecigs possible.

Here's a good tutorial on power supply design if anyone is interested.
Basic Switching Power Supply Design Tutorial
 
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SunRam

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The Provari and the newer Young June (V1.5T and V2.0) lavatubes uses PWM - and is generally regarded as the superior switching regulator, over and above buck/boost regulators. This has been extensively discussed somewhere on ECF, just can't remember where. With PWM you will also get better battery life vs buck/boost regulators.
 

yzer

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Interesting answers, especially regarding Provari using PWM. So, it looks like the voltage regulation on my E-Power 14650 probably uses PWM and my DMM has no problem reading the output. I've had no problems with long draws burning out LR devices down to 1.5 ohms on my E-Power, so the regulation must be pretty good.
 

rondasherrill

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I think its safe to say that most PWM devices out there fall short of being desirable. It's seems like a shortcut to me. My Innokin iTaste does not have PWM and is under $70. If I was a factory and going to use PWM, I'd make sure it was done right, it can't cost much more.

The iTaste DOES use PWM...
 

rondasherrill

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Not surprisingly, this conversation got way over my head really quickly.......but if I put gotvapes flux juice in this...... would it be a flux capacitor??? :laugh: :laugh:

Totally different part of the PV where the liquid goes, BUT with the right capacitor(maybe super capacitor), the right voltage, the right liquid, and the right placement of the leads, it could potentially knock you into the future.

***WARNING: Any perceived time jump will be the result of unconsciousness, as unfortunately our modern perception of physics is broken, leaving time travel impossible***
 

gordong11

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I just got my first Reo Grand delivered today, which is a non-vv mod, but also 100% mechanical. No wires or circuit boards, just whatever voltage your battery is throwing. Which produces the cleanest power possible. what a difference; same atty, same juice, same voltage and it tastes 100% better on the Reo than on the cheap PWM VV mod. Can't get better proof than this that PWM does effect the flavor.

BTW Love this Reo
 
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Butters78

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The reo is great, i sold mine and plan on getting another in the future.. you can allways kick it later to keep the vape constant :)

I just got my first Reo Grand delivered today, which is a non-vv mod, but also 100% mechanical. No wires or circuit boards, just whatever voltage your battery is throwing. Which produces the cleanest power possible. what a difference; same atty, same juice, same voltage and it tastes 100% better on the Reo than on the cheap PWM VV mod. Can't get better proof than this that PWM does effect the flavor.

BTW Love this Reo
 

six

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It's a difference in how power regulation is done. It *can* be done well using PWM... but I've not seen an example of it yet.

Joker AV? -- Setting aside the fact the joker av has never been updated to remove the requirement of using a screw driver to set output voltage, it does seem to create vape temps that are close to those created in the same range from non-pwm devices and battery life is very good. - The joker av isn't really my cup of tea, but I think vaperlife is the only one that seems to know how to tune their pwm output.
 

DaveP

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OK, so I bought this cheap VV mod kit from a store where I belong to their test area, paid $20 and a few days later I got the mod. This VV mod was just basic; has a digital display, vape and voltage up/down buttons, and takes 2 18350 batteries. Without the batteries the mod weighs next to nothing, and the battieres that came with the kit didn't work.

I finally add batteries that work and boom I am vapeing!! Dripping my regular vape on a 1.8ohm Boge 306 atty @ 4.1v and wow this vape tastes horrible, so I drop the voltage to 3.5v and boom it still tastes bad but not as bad. So I throw on my threaded voltage meter and no reading shows up..hmmm? I then decided to throw on a Boge LR carto and vape at 3.5v, and wallah now finally decent flavor. A couple days later this this new carto just dies. I wasn't sure if I should blame the device or a bad carto. Next I try a Bottom Coil phoenix clearo, and again the flavor seems a little off, but not bad enough not to use, and boom a few days later the clearo dies, which was fairly old. Anyway at this point I give up this mod because it just seemed like too much trouble to fiddle with.

A couple days later I'm watching a review of the new VV Gripper done by PBusardo and he talks about the gripper having "Pulse width modulation". I heard of "PWM" before, but none of the mods I own had it, so I never paid much attention to it. Well it turns out the PWM mods will cause a threaded voltage meter not to work. So I connect the dots to my VV mod and come to the conclusion that it has PWM as well, then was able to confirm.

Basically if you have a VV mod with PWM set to 3.0v, the mod is going to fire at 6.0v approx 50% of the time, like 50 times a second to achieve the 3.0v. IMO this is like a jimmy rig and no wonder my juices on this mod tasted funny or bad. I'm using LR atties n cartos on a mod that is firing in 6.0v in essence. This also explains why potentially my cartos were dying quickly. I can't say how ...... off I am that these companies can't provide a mod that fires a steady voltage.

I just wanted to warn others that cheaper VV devices, especially from china, may have this Pulse Width Modulation and they want to consider this when making a purchase, especially a newbie who has no other baseline to compare it to. It may also not affect some people as much as it affected me. Also if you are a high voltage vaper PWM mods won't make a big difference because all your cartos, atties, etc are high ohm. Plus, if you are vaping a PWM mod at 6.0v, there will basically be no PWM.

One thing is for sure, I will never buy another PWM mod, no matter what the price is and I hope others can learn from my mistake. I'm generally a low voltage vaper because I'm big on flavor and dont care much about throat hit. My other mods dont have PWM so I noticed a big difference in flavor. I feel bad for all those newb's who bought unknowingly a PWM mod as their first mod.

hope this helps and serve to warn other low voltage vapers on PWM mods

You might want to turn off all the devices in your home that operate on AC power if you are worried about PWM. The 120VAC power in your house goes to about 170vac twice a second. Once for the positive and once for the negative peaks. The rated power at your AC socket is 120vac, but that's the average RMS (root mean square) value. Remind you of what you see on a PWM scope trace? It's the way things work ... all over.

z_ac.gif


3 ways of expressing voltage of a common AC wave form
 
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