The HumVV Variable Voltage Box Mod

[warbdan]

This is my 2nd variable voltage mod. It's similar to the one BigBlue made using the UCC383-ADJ regulator and a 200k .5 watt variable resistor. The main differences are that I used no caps or resistors and no PCB. Everyting is soldered directly to the regulator like yzrmbsg from VF did. It was pretty simple to build and vapes just like my Evercool. It actually doesn't get hot because the regulator is raised up off of the case so there is plenty of air space on all sides of it. I'm loving it at 4.5v with cartos and 4.2v with 510 atties. Sorry the pics are fuzzy, but my camera doesn't like close-up pictures

Inside:

Here you can see why I call it the HumVV. It's Army green!
Front:

Thanks to BigBlue, WillyB, yzrmbsg, and everyone else who has posted info for mods and helped me with my many, many questions

 

[Para]

I think it looks cool !

 

[breaktru]

Me too. Cool mod. Have you thought about squeezing in a voltmeter? Paralex2 is good with the meter thingeeys.

 

[warbdan]

Thanks Parallex2, That means a lot, because all your mods look so awesome!

Yeah, breaktru, I've been looking around the web for some voltmeters, but all I can find would be too big. If I could find a tiny one, I'd put one in every one of my mods, lol. Where do you find yours, Parallex2?

 

[asdaq]

I like the spartan build with this. Nice job! And I'm much more impressed here than with the toilet paper holder

 

[yello266]

That looks nice. I only wish I understood the tech aspect. I'm hoping to build a mod soon.

come and join me on elixirtv as well as other great hosts.

the mellow yello medley. tuesdays at 8pm est

YouTube reviews at http://m.youtube.com/index?desktop_uri=/&gl=CA#/results?q=canasianada

 

[warbdan]

I like the spartan build with this. Nice job! And I'm much more impressed here than with the toilet paper holder

LOL! Thanks, asdaq. The toilet paper holder with a LR306 is still a helluva vape!

 

[sgtdisturbed47]

I have so far only used caps in my mods while using boost converters. Other than that, I don't see how they are necessary besides theoretically protecting the regulator from the batteries, prolonging the life of the regulator.

I also havent used circuit boards yet, and I've managed to keep my builds safe and very space-efficient.

 

[warbdan]

I may redo this one with a cap on the input. For some reason I'm having the back(negative lead) battery stop producing voltage. Maybe when I hit the button it's drawing too much current and a cap might help. I don't know for sure yet what the issue is. It could just be a bad cell.

 

[AttyPops]

Cool mod. How's it going with the issue(s)? The input cap?

The cap thing has me thinking too. Decoupling it a bit on the input would take it easy on the IC and reduce extreme highs/lows/transients (particularly from switch bounce) I would think. The output cap, on the other hand, only buffers the atty....so who cares? Unless there is some form of back-EMF or capacitance... neither should be a problem with an atty, which I understand to be just a resistor. Or so I would think. Wonder what the pros think about the caps.....


EDIT: from the UCC383-ADJ datasheet with added italics/bold/underline:
VIN: Input voltage, This pin must be bypassed with a low ESL/ESR 1-µF or larger capacitor to GND. VIN can range from (VOUT + VDROPOUT) to 9 V. If VIN is reduced to zero while VOUT is held high, the reverse leakage from VOUT to VIN is less than 75µA.

VOUT: Regulated output voltage. A bypass capacitor is not required at VOUT, but may be desired for good transient response. The bypass capacitor must not exceed a maximum value in order to insure the regulator can start.

I would at least put one on the input....... the typical application shows a 10uf, this says at least 1uf low ESR/ESL...

In fact, I see so many mods that have no capacitor (and have made some too) on the input, and I'm wondering how much havoc the switches are creating for the mosfet's control pins, or Vin, depending on the type. I know what a typical switch bounce looks like on an oscilloscope......ugly. Very ugly.

 

[warbdan]

No, AttyPops. The back battery will still show 0.00 volts when it's ready for a charge (3.2v). My guess is that when these batts get to 3.2v it's easier for the amp draw to hit the protection limits in the battery. I'm still guessing here. Anyhow, charging the batts makes them show voltage again. It's a weird thing, but my Evercool is doing it too. Has no one else run into this?

 

[AttyPops]

I was asking about the input cap....

IDK about your battery issues.......

 

[breaktru]

Hey WarbDan, Do you think that maybe it's a bad Cell? Maybe you should put a marking on the battery and switch positions and see if it happens to the same battery or the one always in your back position.

 

[warbdan]

No, I don't think it's a bad cell. It's happening on both my VV mods and always on whichever cell is in the back. I have 8 batteries and it doesn't matter which one is in the back when it gets to about 3.2v it will suddenly read 0.00v after the mod stops firing. It has to have something to do with the protection circuit in the batteries. I will just have to get some high drain batteries and see if it makes a difference. These trustfires aren't as powerful as I hoped they be.

 

[warbdan]

I've been charging my batteries every night and haven't had this problem since. I think I was just using them too long.

 

[breaktru]

Did you notice a drop off in performance before charging? I do with my V.V. set at 4.8v. Even though the combined output measures 4.8v, performance declines. The individual cells measure 3.4v, and on the charger they go.

 

[breaktru]

Okay warbdan, might have to disregard my last post. I was vaping like a champ and them nada. No reduction in Vapor prior. Pulled the bats and the first bat was 3.25v (bottom neg.) and the top bat. was 3.02v. Put in new bats and checked voltage. It was set at 3.75v. Maybe the dialed setting has something to do with the out come?
I'm using the PTR08100W regulator.

 

[warbdan]

Hmmm, 3.2v on the back battery is where it stops vaping. The front one might still be at 3.4 or even 3.5v, but as soon as the back one hits 3.2v, the vaping stops. This is well over a day of vaping though, so I just started charging them every night and I haven't hit 3.2v again. Usually they are still at 3.4 or 3.5v by the time I put them on the charger.