EverCool Variable Voltage Mod

[rannox]

Just a question I've never found an answer to.

Do POT's have a baseline resistance? i.e. If its a 2k ohm, is it 2k its lowest setting? Or is that how much each full turn is worth? And if that is correct, is that the same for single turn POT's?

I wanna use a single turn dial style for mine, and was looking to clarify before getting one.

Thanks btw.

 

[Rocketman]

In addition to single turn you may want to decide if you want a linear taper or logarithmic taper "potentiometer".





Potentiometer - Wikipedia, the free encyclopedia

 

[rannox]

Thanks for the response. But I think I figured out my question already, haha. I have a bad habit of asking a question and then finding out the answer before people give me an answer.

A POT supposedly should be at 0Ω +/- %tolerance at its lowest setting.

So if I get a 500Ω pot with the PTR08100W it should vary between 5.5v and 3.0v. According to the resistance list in the pdf of about chip.

Im going for a Linear. Linear is a gradual even change, and Logarithmic is a exponentially increasing change in ohms. I prefer gradual.

Was also thinking a slide pot would be nifty. But most of those are log style.

 

[Rocketman]

Plot the voltage versus the resistance and see if the line is linear.

You may even want to plot the resulting wattage (through your normal atty resistance) versus resistance.
It is possible to tailor the resistance curve of a pot to meet you needs.

 

[rannox]

The voltage and resistance in the table on the pdf?

I dont really see how it would matter if their table is based on logarithmic or linear. Considering resistance is resistance no matter how you get it, correct?

 

[rannox]

ah, you have to go and edit your post while im replying, haha.

I see what you mean, Ill probably grab a few different pots to play with since I got a few new modding toys waiting for me under the tree, I might as well use em as much as possible, haha.

Too bad the only pots rat shack has are 10K plus, so I gotta order and wait...

 

[Rocketman]

A 1 turn 500 ohm linear pot is zero ohm (close) to 500 ohms over a 270 degree motion. A ten degree movement of the pot is 18.5 ohms. Each ten degrees is another 18.5 ohms.


Sorry about editing, but my posts are thoughts in motion

 

[rannox]

Lol, no worries, thanks for the math btw.

 

[Rocketman]

One thing to watch with this chip is the maximum and minimum resistances. I don't think this chip likes less than 240 ohms and any thing over 500 is pretty worthless for vaping.
A range of 240 to 482 ohms using a 500 ohm pot and a 470 ohm and a 240 ohm resistor give a reasonable voltage range and easy to set voltages that are useful like the sketch below might work.
This would give you a range from about 5.5 volts to 3.0 volts. and using an audio/logarithmic reverse taper might even be easier to adjust than a linear. But 500 ohm log pots might be hard to find.

 

[tlocke]

OOops, guys, sorry about the missed decimal there. I do understand about switches and their foibles, however, I like the feel of a nice small light switch and am willing to replace it, (2 solder points) I have also left an area for the larger 5 or 6 amp switches that I have laying around. Those are what I am using in all of my current mods, but thought this might be a nice change. For me, half of quitting smoking with ecigs is being able to play with my soldering irons, magnifying glasses, punch boards, etc....

Everyone have a very Merry Christmas and hope the mod fairies turn out in style.

 

[Minus1724]

Sorry, I was just answering your explicit question of "has any one made there MOD with a mini usb female, for charging the 2 18650 batteries, so you don`t have to take them out"...

thats okay.

I`m just a bit frustrated, I really really want one

 

[CapeCAD]

I looked at that one but this turned me off.
Not much room there for 5V vaping.

WillyB, this OKR-T/10-W12 converter is no different than the evercool, all buck converters have a drop off, probably in the mid 80% range. The PTR is running at 300kHz and the OKR is running at 600kHz, so there is a slight advantage to the OKR.

I have been using this model myself and it is no where near 2 volts, closer to .5-1 Volt at full load (10 Amps), so minimum input is between 5.5-6V for 5V vaping at full load (10 Amps) with continuous usage. Since we are only using these in burst mode for a few seconds at a time and only running at 1/4-1/2 load, I don't believe you are going to see a difference.

Now that I have a scope, load, and supply set up I can give you exact specs on it.

This ptr08100 spec is:
The minimum input voltage is 4.5 V or (VO/0.83) V, whichever is greater. That's 6.02 volts minimum for 5V vaping at full load.

My Sepic design will deliver 5v vaping until your batteries are dead, but efficiency suffers slightly (~10%) compared to a Buck converter.

 

[rannox]

One thing to watch with this chip is the maximum and minimum resistances. I don't think this chip likes less than 240 ohms and any thing over 500 is pretty worthless for vaping.
A range of 240 to 482 ohms using a 500 ohm pot and a 470 ohm and a 240 ohm resistor give a reasonable voltage range and easy to set voltages that are useful like the sketch below might work.
This would give you a range from about 5.5 volts to 3.0 volts. and using an audio/logarithmic reverse taper might even be easier to adjust than a linear. But 500 ohm log pots might be hard to find.

Nice, ya I was thinking about putting a resistor in along with the pot. That would be perfect I think. If I cant find a 500 ohm log pot to test ill probably grab a 1k or similar.

Now all i need is for the TI samples to come in and to grab some pots and resistors... Might even try to fit one of those ebay rc li-po voltage readers in there.

 

[CapeCAD]

WillyB

I tested the OKR-T/3 because I did not have any OKR-T/10 outside of a mod, but the results are typical for a buck converter. I suggest you try one for yourself.

When I measured 5 volt 2.05 Amp output, the input requirement was 5.67 volts, 1.99 Amps. (VO/0.88) V

View attachment OKR-T3DropOff.pdf

 

[WillyB]

WillyB

I tested the OKR-T/3 because I did not have any OKR-T/10 outside of a mod, but the results are typical for a buck converter. I suggest you try one for yourself.

When I measured 5 volt 2.05 Amp output, the input requirement was 5.67 volts, 1.99 Amps. (VO/0.88) V

I'll take your word for it. It's nice to have someone respond with some real world numbers.

Using linear regulators, low drop out was important and it just carried over as I read various datasheets. They did flat out say 2V, was there another more detailed explanation I missed? Where with TI's formula at 5V the drop is 1.02V. That does seem significant when it comes to vape times. But now since seeing bigblue's real word efficiency tests comparing the two types I see where drop out volts have less meaning and the other good part is the ability to use smaller batteries and still get very long vape times.

Was that PDF all your results?

I hope you start chiming in more often.


Now I remember you, I think I was probably driving you nuts with all my comments/questions.

 

[CapeCAD]

I'll take your word for it. It's nice to have someone respond with some real world numbers.

Using linear regulators, low drop out was important and it just carried over as I read various datasheets. They did flat out say 2V, was there another more detailed explanation I missed? Where with TI's formula at 5V the drop is 1.02V. That does seem significant when it comes to vape times. But now since seeing bigblue's real word efficiency tests comparing the two types I see where drop out volts have less meaning and the other good part is the ability to use smaller batteries and still get very long vape times.

Was that PDF all your results?

I hope you start chiming in more often.


Now I remember you, I think I was probably driving you nuts with all my comments/questions.

Yes, the pdf was all my results. Thanks to you and your comments I've spent the past few months of all my waking moments researching, simulating, and building a switching converter that will work across all voltage/load requirements.

To do this I had to build a source supply, build test equipment, and borrow a Scope from a relative. This has had the added benefit of keeping my mind off smoking.

I did send a thank you in my SEPIC mod thread

 

[warbdan]

I finally got all the parts in and got it done. I gotta take my hat off to you, BB. This thing is awesome! My box is from digikey and it's Army Green, which I like. It looks a little different. Sorry, these pics are fuzzy, but you can get the idea:
Inside:
http://i172.photobucket.com/albums/w7/warren1977/IMAG0058.jpg

Front:
http://i172.photobucket.com/albums/w7/warren1977/IMAG0056.jpg

Next to my nicostick:
http://i172.photobucket.com/albums/w7/warren1977/IMAG0057.jpg

Thanks again, BB. Your instructions made this build super simple and this mod has made me like cartomizers again

 

[bobrez]

Thanks to all who have posted in thread that made it possible to put this together. I used a 2c modbox from madvapes for my first try, and able to squeeze it all in with room to spare. This lasted for a week before started to bug-out and work intermittent. Thinkin might be the mosfet or cheap tact switch. So having the size needed nailed down came #2. I made a woodie using the horn switch that I like, to eliminate the mosfet an tact, sos all is well.
It holds the volts I set it too for days with no dropout, Nice. I have found my sweet spot tobe between 4.1-4.2 which is hard to get without a regulator. Its like using 18650s fresh off the charger, and it last for days (like 5 days without charging) WOW

 

[WillyB]

It holds the volts I set it too for days with no dropout, Nice. I have found my sweet spot tobe between 4.1-4.2 which is hard to get without a regulator. Its like using 18650s fresh off the charger, and it last for days (like 5 days without charging) WOW

Looks quite nice.

have found my sweet spot tobe between 4.1-4.2

If those are loaded volts (vaping), that's much higher than a freshly charged 18650, and should provide almost 30% more watts.

 

[bobrez]

Looks quite nice.


If those are loaded volts (vaping), that's much higher than a freshly charged 18650, and should provide almost 30% more watts.

Yepper loaded 4.1 is my spot. While using a mod without a regulator and a freshly charged 18650 bat could only manage 2 or 3 hits before it would drop below 4. Thats why im lovin the evercool so much.