My First Pulse Width Modulator Mod

[CraigHB]

Yeah, I wasn't really expounding the "virtues' of linear regs. I just threw that one in as an aside. I give these mods about 3 years before battery technology makes the whole thing moot.

I understand, but that's just me, any reason to flap my gums I think I like to talk about this stuff as much as I like doing it.

What I really want to know is how efficient PWM like this is vs an adjustable switched regulator, end-to-end. Although as stated above, the reg would adjust itself keeping a constant voltage over the battery curve.

Damn near as efficient as a straight wire. You get some loss from the FET, but a good one can keep that under a half percent. There's also some reactive power losses due to parasitic impedance. The higher the frequency, the more you get, but it should be negligible as well. I'd be surprised if it's anywhere near a percent. There's some power used just to drive the electronics. However, smart design should also make that negligible.

Regulators that energize an inductor are not as efficient as straight PWM. I haven't actually measured any of the POL ones, but they claim as high as 96% and that varies depending on load. With the one I'm running, I get 98% at battery voltage with a 3Ω load when the controller is idle. At high loads ~20W, it drops down as low as 92%. Works out to about 95% on average.

 

[AttyPops]

You're way ahead of me. We're also hijacking asnider123's thead a bit. But it's kinda on topic. So you used pwm controller, in combination with an induction coil, to make you own booster? Or did I read it wrong?

+1 on the digital pots. Up/down buttons vs thumb wheel. Like. It may have been breaktru or WillyB (not sure) that was using digital pots. I know of that thread (I think) and it had up/down functionality without I2C (don't remember how/if bounce was handled tho). If they'd integrate two small up/down buttons into a pot with debounce.... gold. I remember that thread, I'll dig around. Seems like I went searching for this.

Not very cost effective to use a controller soley to drive a pot.

well... PWM and the pot. Also output (display or led), and input. If ambitious, atty ohm measurements and v-in measurements. Still, I haven't been motivated enough to break out the PIC programmer for an e-cig. I want to keep em simple. Maybe it's just me.

 

[chrism]

asnider123,

I have read your vv box tut on a different site.
Good stuff.

 

[CraigHB]

Yes, the circuit asnider123 posted is basically part of a DC-DC controller chip. In the most simplest sense, it's just that, except it also incorporates a feedback network to control output voltage. Doing it with a PWM generator would require additional control circuitry. Of course, there would be no reason to do that since there is a wealth of DC-DC controller chips on the market already.

Generally speaking, these things are tricky to design even when using an off-the-shelf controller. Firstly, there's the frequency issue. Most of the POL regulators (mine as well) run around 600kHz. You can get into issues with capacitive loading on the FETs with frequencies that high. You need a fast one with low gate charge. You can also get issues with circuit board layout. Then there's the inductor. If you wanted to run at say 50kHz to mitigate frequency issues, you'd need an impractically large inductor.

That's the great thing about POL regulators, all that esoteric stuff is dealt with for you. Designing these types of converters is hard to do even with a controller. There's all kinds of issues you need to deal with. I spent a couple months working out the design on my current one, bode plots, simulations, frequencies, inductor values, capacitor and ESR values, compensation. All that stuff is pretty hairy. I need to do it in some part again to swap out these ridiculously expensive tantalum polymer caps with cheaper ceramic ones.

Oh, and sorry asnider123 for going all over the place with this thread. I really have a tendency to go off on any tanget. I'll try to watch that.

 

[asnider123]

No problem guys, this is really interesting and on-topic as far as I am concerned. Keep up the excellent conversation.

 

[danman1453]

There is a website where some ppl who aren't e-cig users may be interested in this conversation. Also a very good source for DIY electronics. IE home made reflow stations, DIY digital soldering stations, etc.

hackaday.com

Been browsing that site for years. Some of the articles are simply amazing.

 

[Dalton63841]

There is a website where some ppl who aren't e-cig users may be interested in this conversation. Also a very good source for DIY electronics. IE home made reflow stations, DIY digital soldering stations, etc.

hackaday.com

Been browsing that site for years. Some of the articles are simply amazing.

Seconded. I don't comment over there, but I have been reading hackaday forever. TONS of great stuff over there.

 

[breaktru]

Interesting site

 

[sierra22]

way to go asnider! looks sweet!

 

[CraigHB]

There is a website where some ppl who aren't e-cig users may be interested in this conversation. Also a very good source for DIY electronics. IE home made reflow stations, DIY digital soldering stations, etc.

hackaday.com

Been browsing that site for years. Some of the articles are simply amazing.

Cool, thanks for that. I just read an article on over there on PCB flux removal which always has a been a source of annoyance for me.

Big site though, hard to sift throught the stuff that's interesting to me.

Hehe, just got stuck in the "misc" section for a few hours, some good stuff in there.

 

[clutchjunkie]

So, I finished my first v-pwm mod last night and I have been using it exclusively all day. There is an interesting by-product of pwm on most cartos ans atties - it seems that the pulsing vibrations going through the coil help to get juice in there better. I am getting massive, flavorful hits even on atties that were not that good before. With ce2's especially I can get massive heat and vapor that I couldn't get before because they would just burn on a normal vv mod turned up that high.

My setup is running between 150khz to 200khz if my math is right.

 

[Noodoggy]

let's see some pics and circuitry! awesome that its working great!
that is interesting about the vibrations too. it makes some sense though, because i notice when vaping cartos esp but sometimes attys that if i rotate it i get a better vape. i know that has to do with wicking but the vibrations might affect capillary action in the wick. congrats on the v-pwm mod! may your vaping be long lasting!

 

[CraigHB]

Sounds really cool. That may be a good point on the pulsing heat. It could very well have an effect on vaporization. Pulse frequency could make a difference too. You should try lowering frequency, might enhance the effect. Love to see a pic or two.

 

[clutchjunkie]

Later when I am near a computer I will make a schematic for what I used, as far as pics I put the circuit in my VVii mod after I toasted the ti 08100 that I originally had in there. The whole circuit fits between the faceplate and the back of the battery housing, the ti chip was actually too thick to fit there. There's pics of the original mod in my "seriously thinking about modding A wiimote " thread.

 

[AttyPops]

I think someone said it in another thread.... it's like a flux capacitor. Hit your head, and when you wake up, you have a vision of the flux-atomizer and ....time travel. I think you need a DeLorean to make it work tho.

Seriously, sounds good tho. Remember that it's 6.x volts pulsed, so it is hotter, but only briefly, then shuts off for the remainder of the duty cycle. It nets out to <whatever> volts over time.... I wonder if it's harder on the coils too... like 5v is harder on em than 3.7. Or different sized coils having different reaction times, so frequency matters, since a coil doesn't heat instantly, nor cool instantly. Could be that you just put more effective energy into the juice by turning it up? This whole thing could get into heavy thermodynamics... but better to go by experimentation.

 

[bstedh]

Well, I may just have to try this now.

I have been researching Hackaday and am going to build myself a variable soldering iron with a dimmer and also try the hot plate reflow method to assemble a board. I can just grind down the tip of my existing iron to get that nice pointed cone tip. I just have to figure out how i'm going to make the PCB. I will probably keep the frequency capacitor through hole so that I can experiment with different frequencies.

 

[asnider123]

Been out of town .. just got back and checked the forum. I am glad to hear of your successes, clutch!! Gotta see which design you used for the electronics!! You are a pioneer!

 

[donptal]

Can,t wait to see your finish product asnider. I'm interested in doing this also, based on clutchjunkies self review I believe that this is a totally different vaping experience to us modders.

@ clutch

Will you be so kind to let us make a peek of your design for us to immitate lol.

 

[CraigHB]

I have been researching Hackaday and am going to build myself a variable soldering iron with a dimmer and also try the hot plate reflow method to assemble a board. I can just grind down the tip of my existing iron to get that nice pointed cone tip. I just have to figure out how I'm going to make the PCB. I will probably keep the frequency capacitor through hole so that I can experiment with different frequencies.

I was reading about soldering on Hackaday too, lots of good info there. For your variable temp soldering iron, if you can somehow rig up a temperature indicator, that will help a lot. I know I rely heavily on the one built into mine.

One thing I found interesting was the "drag" method of soldering IC chips with high pin counts. I've actually done that inadvertently with my fine tip iron and it does work. No matter the result, desoldering braid is very good at fixing screw-ups on IC pins.

I've done very little of my own reflow. I know of the toaster oven method and I've used that one on occasion. So, you can use a hot plate? How does that work?

One issue with tips, you really need the nickel plating on them. If you want to grind your own tips, copper is going to give you trouble. You might want to looking into a good material for that.

 

[bstedh]

I was reading about soldering on Hackaday too, lots of good info there. For your variable temp soldering iron, if you can somehow rig up a temperature indicator, that will help a lot. I know I rely heavily on the one built into mine.

One thing I found interesting was the "drag" method of soldering IC chips with high pin counts. I've actually done that inadvertently with my fine tip iron and it does work. No matter the result, desoldering braid is very good at fixing screw-ups on IC pins.

I've done very little of my own reflow. I know of the toaster oven method and I've used that one on occasion. So, you can use a hot plate? How does that work?

One issue with tips, you really need the nickel plating on them. If you want to grind your own tips, copper is going to give you trouble. You might want to looking into a good material for that.

The hotplate method is simple and seems like people have been having better results than the oven. Just lay your one sided board on the hotplate and turn it on. You may need to experiment a little bit to see what your temperature curve will be. Also depending on the heating element spacing people are placing a piece of aluminum in the hotplate as a heat spreader for a more uniform heat. Otherwise it's basically the same as the oven method without the overhead heat to melt components.

I have a temp probe for my multi meter and I also have an IR temp reader somewhere in the garage that I never had a use for so I will have to search for that also.

With the tip, I do agree that a manufactured one would definitely be better. However, You can grind your own but you need to constantly clean and re-tin it and it will work good. The big trick is smoothing it out really good. Even polishing it with a dremel to get the best results. But you definitely have to continuously clean and tin it while you are using it. I use a wet Scotch Brite pad instead of wet sponge to clean the tip as I am using it. It helps to clean the oxidation and burnt flux off so you are not dealing with the heat robing crud as you use it.