EverCool Variable Voltage Mod

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WillyB

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Correct me if i'm wrong but wasn't there some discussion earlier in this thread concerning a mosfet instead of the inline switch?
I would imagine if you search you'll find hundreds of posts concerning mosfets; types, pros and cons, wiring diagrams etc. on these forums. As someone who now sells mods for profit, it may be best to do your own research.
 

Madshock

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i was confused as well.

Correct me if i'm wrong but wasn't there some discussion earlier in this thread concerning a mosfet instead of the inline switch?

Yea, i believe it was me with a problem. haha... Anyways, it is up to you to use a Mosfet for a tact switch. I believe theres a diagram of it somewhere that incorporates a mosfet but i couldnt find it. Add the mosfet before the power input to the chip.
 

givesuhe11

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HUH? What does that mean? The regulator controls the output, how does it "takes the place of the mosfet"?

Hahaha... now THATs one of the funniest things Ive read on this forum!

@woodsmith... here's the circuit with the mosfet that Bigblue put up in an early post... hope this "HELPS"

spdfm8.jpg
 
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rannox

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I'm confused. What's the purpose of the Mosfet? Is that used to limit the current thru the fire switch? Doesn't the evercool use Pin 1 as a Inhibitor control pin?

I believe people are using it so that they can use a tact NO switch instead of a NC, since they are easier to come by (rat shack, etc.).
 

WillyB

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I'm confused. What's the purpose of the Mosfet? Is that used to limit the current thru the fire switch? Doesn't the evercool use Pin 1 as a Inhibitor control pin?
Yes that's correct, but if you notice biggie chose not to go that route. Father knows best?

And FWIW a fire switch on Vin means no current to the regulator till you press it. The same cannot be said for either a mosfet or enable pin fired mod. The reg is always 'live', just resting.
 

breaktru

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Thanks WillyB, I went with Father biggie for my build. I guess if your using 14mm batteries in a "AAA" box that already has an "ON/OFF" built-in, the fire switch circuit would then make sense. Otherwise the circuit from the data spec's for the evercool that bigblue showed in his original post is the way to go. At least for my application.
 

squirrel64

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Sorry if this has been asked before, I did search but I have a couple of issues confusing me. 1) Are all 3 of the legs on the pot a contributing factor on the final voltage ? Or could this just be hooked up with the left and middle leg. 2) Can pot and 220ohm resistor configurations (values ) be changed ?
 
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kjj

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No, one of the legs is floating because of the cut trace on column 2. You don't need to solder it in, and you actually need to be really, really sure there is no chance of connection. Cut the trace on the board, even if you don't solder the pin in, and probably even if you cut the pin off of the pot before assembly. If it does connect, at best you'll waste a bunch of power. Or, you'll melt the pot. The worst case involves making your batteries very angry.

The 220 ohm resistor is there to keep VOAdjust from shorting to ground if you bottom out the pot. The datasheet actually says 240 ohms minimum, but 220 is a standard value in the 10% series. While they are probably being a bit conservative, you don't want to go any lower.

There probably isn't much point messing with the nominal pot value. The output voltage is well under what most of us would consider useful vaping voltage with just a couple hundred ohms (in addition to the safety resistor).

Edit: Just to be clear, by column 2, I mean the one on the right, under pin 2 of the chip. Forgetting to cut the trace as shown in column 4 (which is the 2nd column from the left side (where we normally start counting)) would be bad too, but with slightly less severe consequences, maybe nothing worse than letting the magic smoke out of your expensive regulator. Just be sure to cut them both, as shown.
 
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Java_Az

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I believe the original circuit on this uses 2 of the trimmer legs. left and middle leg are used. The one on the right at f2 is isolated your supposed to clip the copper between f2 and e2.

Values can be changed i would look at the data sheet on the chip it has all the info on it. They do say on the sheet not to go lower then 240ohms but some peeps have been using a 220ohm resistor on it. I dont think anyone reported the voltage they were getting though with a 240ohm it sets the max voltage to 5.5 volts. 220ohm should bring it up a bit higher. If you wanted to set a max of 5 volts you would slap a 268ohm resistor on it. As far as the trimmers they would work you the other way. with the 200ohm trimmer used in this it will give you low end voltage of 3.4 volts. If you wanted it to go down to 1.6 volts you can slap a 1 k trimmer on it. This is all in the data sheet if you want to check it out.
 
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