Variable Voltage mods and pulse width modulation

Status
Not open for further replies.

gordong11

Super Member
ECF Veteran
May 24, 2012
387
145
54
Delray Beach, FL (SE FL)
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
 
Last edited:

JakeTheV&pe

Senior Member
ECF Veteran
Nov 5, 2011
145
42
Winchester UK
See I wounder if my Torpedo VVV has PWM, anyone have any thoughts on this?.

It is obviously a chine made one that has been rebranded by Totally Wicked. Not as cheap as $20 as it cost me £57.00 reduced from £75.00.

I am hoping so much there will be a provari for sale at the UK vapefest this year, I have the money waiting and cant wait to finaly get my mitts on one! :D
 

rondasherrill

Ultra Member
ECF Veteran
May 19, 2012
2,247
1,941
Valhalla
For the record, almost all boosted APV's or APV's with a switching regulator are using PWM. I think the difference is whether or not the output is "filtered" or not. If the output is filtered, that means that it goes through an inductor or capacitor to smooth out the waveform, instead of going to the atomizer in a "all then nothing" form...

Unfortunately, most APV's don't say whether or not the PWM is filtered or not.
 

Debadoo

ECF Guru
ECF Veteran
Verified Member
May 18, 2012
18,052
133,968
Texas, near Fort Hood
sounds like you may have gotten an ovale v6, possibly v8. Most reviews on v6's were bad that I saw. v8's were better. I just got the vv gripper, knowing full well that it was pwm and that's what I wanted to try. I love this thing! It's a definitely learning curve to setting my volts on it, from what I used on my vtube, but this thing is a little powerhouse!

We're all different, and like different things, so I'm not saying you're wrong at all, but there are a lot of folks who really like the pwm technology. I am fairly new to vv's, and have never tried some of the much higher end ones, but I've heard several provari owners say they like the gripper better than the provari even. Just tossing out a different view point.
 

cozzicon

Ultra Member
ECF Veteran
Verified Member
Jun 19, 2010
2,564
900
Chicago IL
I'd have to chime in on this as well. I'm not really a fan of controlling energy output (wattage) through a PWM cycle.

I've got a unreleased chinese VV mod I've been asked to test, which I cannot get the wattage low enough for me to enjoy the vape. It seems to completely leave the larger part of the market (big capacity, regulated, low to medium wattage) totally out of the loop.

PWM on a regulated VV mod doesn't hit the mark for me.
 

AttyPops

Vaping Master
ECF Veteran
Jul 8, 2010
8,708
134,059
Hc Svnt Dracones - USA EST
Betting it depends a lot on the algorithm and the pulse frequency. Fast enough, and you wouldn't know the difference. (guessing).

Also I'd calculate effective wattage, not voltage if I was setting a duty cycle. I understand some e-cigs use a lookup table for the calc, rather than just say "3.0 v is 1/2 of 6 v". Also, input voltage must be measured to set the duty cycle properly. So... bet there's a lot of kinks to be ironed out.

Bottom line that I'm trying to ramble about here is that there are other PWM modulated e-cigs on the market that are very successful. For example, I believe the eGo series (at least some of them) are PWM modulated to around 3.4 volts.

So to say PWM=bad.... IDK. Not sure it's that simple. You could say "Modulation for <make>/<model> is not very well done."
 

AttyPops

Vaping Master
ECF Veteran
Jul 8, 2010
8,708
134,059
Hc Svnt Dracones - USA EST
Yeah, and like rondash.. said above.....

Voltage regulators ARE pulsed. Even the simple linear regulators are pulsed...they just use comparitors or whatever (logical diagram idea here) to switch between output and ?resistance/ground? very fast. Over simplification to be sure, but there's a frequency to all these things...not all are perfect square waves though.

linreg-block-diagram-1.png


I'm sure the EE's can pop in and beat me up on this... but you get the idea.

It's implementation specific as to how well the PWM concept works in an e-cig.
 

cozzicon

Ultra Member
ECF Veteran
Verified Member
Jun 19, 2010
2,564
900
Chicago IL
Yeah, and like rondash.. said above.....

Voltage regulators ARE pulsed. Even the simple linear regulators are pulsed...they just use comparitors or whatever (logical diagram idea here) to switch between output and ?resistance/ground? very fast. Over simplification to be sure, but there's a frequency to all these things...not all are perfect square waves though.

linreg-block-diagram-1.png


I'm sure the EE's can pop in and beat me up on this... but you get the idea.

It's implementation specific as to how well the PWM concept works in an e-cig.

You're referring to filter capacitors. Usually used on the output of a rectifier used to convert AC to DC or circuits that create pulsed DC like a buck/boost. It doesn't matter if the wave produced is sinusoidal or not. Capacitors create the DC.
 

AttyPops

Vaping Master
ECF Veteran
Jul 8, 2010
8,708
134,059
Hc Svnt Dracones - USA EST
??? Um... I wasn't talking about the output filtering or capacitors at all. Not that output filtering isn't relevant. Just that everything is pulsed even for simple linear regulators.

That diagram is a logical internal diagram for a simple linear regulator.... they often use caps on the input/output... but it's not part of that post.
 

cozzicon

Ultra Member
ECF Veteran
Verified Member
Jun 19, 2010
2,564
900
Chicago IL
??? Um... I wasn't talking about the output filtering or capacitors at all. Not that output filtering isn't relevant. Just that everything is pulsed even for simple linear regulators.

That diagram is a logical internal diagram for a simple linear regulator.... they often use caps on the input/output... but it's not part of that post.

Ok.. You win.
 

AttyPops

Vaping Master
ECF Veteran
Jul 8, 2010
8,708
134,059
Hc Svnt Dracones - USA EST
Win? lol. Not an argument, but I just didn't know where that came from.??????? FYI - I did a google image search to find the diagram, it was buried in a long tutorial/discussion about PSUs...but it was the diagram I was after not the context. :) Could have been on a "how to power UFO's" site for all I cared. ;)

I just think that a lot of people liked the eGo units. And they were PWM. So I think the OP, and others reading this, may want to know that results/design vary a lot. And the linear vv reg I'm using right now has no output caps. Works fine for me anyway.
 
Last edited:

cozzicon

Ultra Member
ECF Veteran
Verified Member
Jun 19, 2010
2,564
900
Chicago IL
Win? lol. Not an argument, but I just didn't know where that came from.??????? FYI - I did a google image search to find the diagram, it was buried in a long tutorial/discussion about PSUs...but it was the diagram I was after not the context. :) Could have been on a "how to power UFO's" site for all I cared. ;)

I just think that a lot of people liked the eGo units. And they were PWM. So I think the OP, and others reading this, may want to know that results/design vary a lot. And the linear vv reg I'm using right now has no output caps. Works fine for me anyway.

PWM as a battery saving strategy (eGo) is not PWM as a VV strategy. They are completely different animals. PWM has many ways of being implemented and for different reasons.

If you're not smoking I'm happy.
 

gordong11

Super Member
ECF Veteran
May 24, 2012
387
145
54
Delray Beach, FL (SE FL)
Wow, My point was well received, thanks. The taste of juices when dripping in an LR306 is noticeably poor in comparison to my other mods. No matter the frequency of the PWM, I don't think it can fix this. It just seems like such a cheap way to make a mod, and you can't even use a threaded voltage meter to test the voltage. The mod I bought cost $20 because I'm a tester, if it was on the regular shelf I'm guessing the price would be $50-$60.

I don't think vendors post whether or not a mod uses PWM, but they should. In fairness to vendor, I don't think a China supplier would tell them a mod they are selling has PWM. They can't be proud of the fact.

Keep on vap'ing.
 

cozzicon

Ultra Member
ECF Veteran
Verified Member
Jun 19, 2010
2,564
900
Chicago IL
Wow, My point was well received, thanks. The taste of juices when dripping in an LR306 is noticeably poor in comparison to my other mods. No matter the frequency of the PWM, I don't think it can fix this. It just seems like such a cheap way to make a mod, and you can't even use a threaded voltage meter to test the voltage. The mod I bought cost $20 because I'm a tester, if it was on the regular shelf I'm guessing the price would be $50-$60.

I don't think vendors post whether or not a mod uses PWM, but they should. In fairness to vendor, I don't think a China supplier would tell them a mod they are selling has PWM. They can't be proud of the fact.

Keep on vap'ing.

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.

On e-cigs that use a buck/boost regulator filtered to provide DC, the output is generally accurate against the displayed voltage if you run the formulas for wattage. And it's simpler to pull off. With PWM you have to calibrate the length of the pulse based on what wattage you want.

I'm still befuddled why anyone would use PWM for regulation, when the same result can be had with a consistent DC voltage.
 

DaveP

PV Master & Musician
ECF Veteran
May 22, 2010
16,733
42,645
Central GA
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. An RC network or just an inline capacitor across the output would make it read on the inline DVM by storing the voltage until the next pulse comes along.
 
Last edited:
Status
Not open for further replies.

Users who are viewing this thread