Maker Pro
Maker Pro

Expanded Electronic Cigarette circuit design

mathphobe

Sep 3, 2017
23
Joined
Sep 3, 2017
Messages
23
New to the forum and still finding the lay of the land here. Been enjoying some of the topics, especially the free energy ones lol.

So.. Vaping.. also always the focus of much debate. I fear some may steer clear of this discussion in leu of this though I do hope not.
In my view its the best smoking cessation device ever conceived and is capible of saving millions of lives world wide so I'll handle any criticism/questions that might arise.

I've been a vaper for some time, I'm also a fabricator and keen tinkerer. Of course that meant I had to make my own. I've completed a few projects now, some using mosfet switch, various pwm, naos raptor and oklt20 chips, alone and in parallel.
Making these opened up various other possible applications, the first was pyrography. While making a wooden box to house the circuit I decided to decorate it using various branding and carving techniques. Shortly after I added a motor, torch, soldering iron application etc etc. It soon became a handheld power bank with multiple attachments.

I now have several unfinished projects floating around. Seems once I have an idea I soon find a better way of doing it. Most annoying!

I'm here to ask the help of forum in deciding a 'best solution' circuit that will fit all my projects.
Ideally I need an smps system, though I've found some of my applications have very low resistance, this means massive current drains, in some cases they've been over 200A! Way beyond the capibilities of any available smps chip I've seen. Luckily by that point I'd surpassed using Li-ion cells and I'm now using very capible 1s and 2s lipo li-hv batteries. Pwm works quite well, especially 10-25khz, but it's not suited to every application unless I can make it an analogue output, but a 200A rc filter??. Linear regulation works very well indeed, but I cannot use big enough heatsinks in my boxes and the losses hence have a huge impact on battery life, so in retrospect it doesn't work at all.

If any of you have very high current, pretty low voltage (4.2 & 8.4v) variable voltage/current circuit ideas I'd be very open to seeing and considering using them. Or maybr you know of a system containing something I can use? The criteria is for them to be as small as possible, handle massive current, generate least heat and be as efficient as possible..

So basically, all I need is the holy grail, nothing much. lol

Looking forward to the discussions.

Mick.
 
Last edited:

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
Core saturation is the usual limitation on SMPS designs - given I haven't seen any 'massive' ferrite cores (you could stack them though) but there's nothing stopping you paralleling multiple (smaller - but still high current) modules and developing a system that brings extra modules into operation as the current draw increases.
 

mathphobe

Sep 3, 2017
23
Joined
Sep 3, 2017
Messages
23
You might have noticed from my title, math isn't my strongest subject. Designing a circuit isn't something I'm apt at doing. Copying a schematic however..

The highest current smps I've found suitable was the oklt20. I did parallel it for 40a once, copying a schematic I found online. Though it worked well I found the voltage control a little unruly. A digital pot would have sorted that out but again, I'm not a math guy. I couldn't work out how it would be done, the chips were easy to find but I struggled selecting the right passives.
There are other issues to considder, multiple 1/8th brick sized smps circuits and a lipo battery end up too large for a hand held pocketable device and the overall cost of such would be significant.

I found this circuit online that I'm sure assembled correctly could handle very high current Pm91R.jpg I've researched at all the components and once built it should be small enough. The controller in that schematic is programmed, I'm not able to do that however I'm sure there are chips I could use that are passively controlled. As you mentioned it, the 78uh inductor there is the only component I cannot find a suitable one of.
 

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
Well you could go 'brutal' and adapt such devices as Lidl's inverter welder (good for 80A so purchase three!) indeed there may well be other welders that would adapt or you could search for hacking mods of standard PC power supplies.

Given PC power supplies vary from 300W and upwards, they contain all the parts and control circuitry to develop 12V at the full rated output (an 800W PSU could be easily rewound to remove the 3.3V and 5V windings and a new 12V winding - heavier wire basically - put in its place) and.... ta dah.... 12V at 70-ish amps. Could be done relatively cheaply if you know a local PC repair shop that chucks out older PSU's????
 
Top