PWM..... What is the attraction?

[The_Professor_2019]

So I have been reading a lot of posts that end up talking about PWM.

I got wondering what the attraction is?

And also wondering what control a PWM mod has?

Not that it is something that attracts me, but I deal with PWM at work, and so I have a professional interest.

What frequency do the PWM mods run at?

Do you have any adjustment on frequency?

What about the duty cycle? Do you have any adjustment on duty cycle?

The machine I am currently building uses a modified PWM waveform. And by changing frequency and duty cycle, the overall effect is huge.

Currently my testing is based on 25/75 duty cycle at 100Hz. However my calculations show I will get a better quality of machining if I use 415Hz on the current process.

In fact, on the next generation of equipment, I will have the ability to run up to 500MHz then I can use a wavelength factor with the minimum order of harmonics....

Also I admit that my interest is not really vaping based, but (as is my tendancy) I do find it very interesting. Do you have to take into account Skein effect?
Do you have to ensure the wavelength of your mod is related to the length of the coil in your atty?

Do you shape pulses not to be a true square wave, but a peak, average and a drop off?

Tell me more
(By the way, just to put my machine in context)
Am running 14.3v
Gap impedance (imagine is a coil resistance) 0.03 ohm
Wattage? This peaks at just over 94000 watts

 

[r77r7r]

There is a utube reviewer that showed test results while testing our older equipment. P. Busardo.

 

[The_Professor_2019]

thank you...

 

[Katya]

No attraction.

Search Results for Query: pwm | E-Cigarette Forum

 

[Katya]

There is a utube reviewer that showed test results while testing our older equipment. P. Busardo.

 

[SupplyDaddy]

I can't get into the specs like you want, but the attraction for many is that PWM can be made cheaply by just about anyone that can handle a soldering iron.

Even fancy controlled PWM mods can be made for about $9. Ive gotten pre-maded and populated boards for about $20. Drill a few holes in the case you want to use, throw in a series battery holder and off you go.

 

[Rossum]

It's just a down and dirty way of doing variable voltage.

 

[Doffy]

i think i read in another thread that you are a long term vaper?

do you remember the vamo v3? was about the first mod to let us pick between this or root mean square

some preferred RMS because it was a smoother draw with no tut-tut-tut effect. Others preferred the mean/pwm because it felt like higher than the max 15 watts (for reasons i don't understand)

 

[RayofLight62]

Once upon a time, vape mods using a syncronous rectifier were a rarity. A Schottky diode was mostly used, but with a great toll on efficiency.
Therefore, variable voltage eGo batteries and the first waves of vape mods, did use PWM into the coil to achieve regulation without a diode penalty. FYI the frequency used was 20 Hz, voltage 5.5 V, 10 - 100% duty cycle.

Thankfully, low channel resistance (RDSon) MOSFETs become later commonplace, and it was how the pain of PWM regulation was delivered to the dustbin.

As mechanical mods "technology" and few other bits of old vape devices, PWM has been made a "legend" by some, so you can still find some mods driving infrasound Square waves into the coil.
They are an anachronism IMO, but some vapers do like them. Pulsing coils improves wicking (which is true).

Dicodes mods have a special mode, they call it "heat protection", which pulses the coil at various rate, a mode I use with RTAs with too much wicking on purpose (to avoid leaks).

 

[The_Professor_2019]

After having a read, it seems to be more sales than anything...

Certainly at the moment. As far as batteries can tell it is just being used for power control......

I wondered if it went further, and opened up more possibilities.

Also (as long as I can remember, RMS is not applicable here!)

RMS or Root Mean Squared is a way of measuring AC.

Now people may say that a PWM waveform is AC, because it turns on and off. No, it is just pulsed DC.

AC swaps polarity from positive to negative. Therefore the average over a waveform is zero. RMS is a way of calculating this without the negating effect of the negative polarity side of the wave....

The interesting effect is the rise in peak current.
For a 50/50 waveform, the part of the wave that is on, draws twice the current, and then it drops off.

Imagine if you will, a 10v 1amp DC supply to a 1 ohm atty, 10 watts....

If you use a 50/50 PWM, 10v, 1ohm atty..

Still 10 watts. Average current still 1amp, but peak current is now 2 amps for half the time....

I must admit, that my mind was working on the expectations that there was more control than just at duty cycle. I even wondered if the frequency was adjustable to cause resonant fracturing of molecules to release more flavour.....

But no, it is just a basic system....

 

[The_Professor_2019]

i think i read in another thread that you are a long term vaper?

do you remember the vamo v3? was about the first mod to let us pick between this or root mean square

some preferred RMS because it was a smoother draw with no tut-tut-tut effect. Others preferred the mean/pwm because it felt like higher than the max 15 watts (for reasons i don't understand)

And yes, I am a long time vaper....
And somewhat of an electronics wizz....

I used to design welding equipment.... Pulsed waveforms completely change the characteristics of a weld.... Simple electromagnetic distribution tests show that well.

I now design EDM and ECM machines, and again, waveforms are vital. Both in the amount of material removed and also the definition compared to drawing.

Hence my interest in the PWM aspect.

But for vaping, straight DC, mech mods are the way I like it.

 

[Baditude]

The Rattlesnake Effect- Why the Cheapo VV [Exception Itaste MVP ...

I the early days of variable voltage, the frequency of the output signal varied from 33 Hz (the Vamo) to up to 800 Hz (the Provari). Vapers who used the Provari, iTaste MVP, or a DNA mod claimed that their vape was "smoother" than the cheapo mods which had a 33 Hz chip. The lower frequency was said to make a rattling sound, hence the term "The Rattlesnake Effect".

 

[r77r7r]

No attraction.

Search Results for Query: pwm | E-Cigarette Forum

Lol, my old avi.

 

[The_Professor_2019]

In my list of devices in another post, I had missed out my Vamo.... I had one for a while, when I spent time and re-machined the body of my sonic....

I had bought a sonic screwdriver (official Dr. Who licenced product) for my son many moons ago, and so it gave me chance to take it to my machine shop and more accurately copy the design into my Sonic Screwdriver Mod

 

[jandrew]

The Rattlesnake Effect- Why the Cheapo VV [Exception Itaste MVP ...

I the early days of variable voltage, the frequency of the output signal varied from 33 Hz (the Vamo) to up to 800 Hz (the Provari). Vapers who used the Provari, iTaste MVP, or a DNA mod claimed that their vape was "smoother" than the cheapo mods which had a 33 Hz chip. The lower frequency was said to make a rattling sound, hence the term "The Rattlesnake Effect".

I still have a rattlesnake Zmax mini from 2013 ... didn't like it for vaping much so it was relegated to use as an ohms reader (more convenient than the DMM I was using at the time).

 

[TrollDragon]

No rattlesnake on my DIY PWM, Big Al's boards run at a dead silent 25kHz.

 

[TrollDragon]

It's just a down and dirty way of doing variable voltage.

How so? The board puts out the current voltage level of the batteries, there is no buck or boost.

 

[Rossum]

How so? The board puts out the current voltage level of the batteries, there is no buck or boost.

PWM can be thought of as a crude form of "buck".

 

[Rossum]

The interesting effect is the rise in peak current.
For a 50/50 waveform, the part of the wave that is on, draws twice the current, and then it drops off.

Imagine if you will, a 10v 1amp DC supply to a 1 ohm atty, 10 watts....

If you use a 50/50 PWM, 10v, 1ohm atty..

Still 10 watts. Average current still 1amp, but peak current is now 2 amps for half the time....

Huh? How does a does the same resistive load draw twice the current from the same voltage supply?

 

[zoiDman]

So I have been reading a lot of posts that end up talking about PWM.

I got wondering what the attraction is?

And also wondering what control a PWM mod has?

Not that it is something that attracts me, but I deal with PWM at work, and so I have a professional interest.

What frequency do the PWM mods run at?

Do you have any adjustment on frequency?

What about the duty cycle? Do you have any adjustment on duty cycle?

The machine I am currently building uses a modified PWM waveform. And by changing frequency and duty cycle, the overall effect is huge.

Currently my testing is based on 25/75 duty cycle at 100Hz. However my calculations show I will get a better quality of machining if I use 415Hz on the current process.

In fact, on the next generation of equipment, I will have the ability to run up to 500MHz then I can use a wavelength factor with the minimum order of harmonics....

Also I admit that my interest is not really vaping based, but (as is my tendancy) I do find it very interesting. Do you have to take into account Skein effect?
Do you have to ensure the wavelength of your mod is related to the length of the coil in your atty?

Do you shape pulses not to be a true square wave, but a peak, average and a drop off?

Tell me more
(By the way, just to put my machine in context)
Am running 14.3v
Gap impedance (imagine is a coil resistance) 0.03 ohm
Wattage? This peaks at just over 94000 watts

Two Questions...

What Era were those posts from that talked about PWM in Vaping Mods?

What is the "Skein Effect" as it relates to e-Cigarettes?