Check My work Nicostick Mod

[Pendarus]

Being the geek I am I put together a schematic for my first nicostick!

I will be using a 2 AA box from mad vapes with a 14500 battery, and a 801 connector. I will also be using a mosfet to switch the atty.

I am still learning eagle so there maybe some dumb mistakes.

Here it is:

 

[caesar]

Looks good, go for it!

 

[Wireguy]

I assume the mosfet is acting like a normally open relay, if so it will work.

What I was wondering is in a box mod you usually can use a switch rated for the job and wouldn't need the extra device with the added possible point of failure.

Of course if you are just doing it for the heck of it that I could understand. Especially since I've been known to do that myself.

 

[Pendarus]

I assume the mosfet is acting like a normally open relay, if so it will work.

What I was wondering is in a box mod you usually can use a switch rated for the job and wouldn't need the extra device with the added possible point of failure.

Of course if you are just doing it for the heck of it that I could understand. Especially since I've been known to do that myself.

Using the mosfet will take the strain off the switch, extending it's lifespan. Also, it is believed but not proven, that the mosfet gives better vapor. Unless someone has debunked that by now.

The mosfet I am using is rated to 50V and 15A, so I am not worried about it being a point of failure.

Plus I like the cool factor. If this goes well I plan to add a booster to my next mod, with a 18650 battery.

 

[Wireguy]

Plus I like the cool factor. If this goes well I plan to add a booster to my next mod, with a 18650 battery.

Yea I can understand that.

As far as point of failure you are right. I just like to minimize my points, unless of course I'm playing. These are really fun to play with. No deadlines, dosn't matter if it works the first time, no rules.

As far as the mosfet creating better vapor I don't buy it. A relay even if its a mosfet doesn't increase voltage. Unless it has a booster function built in. In this case the voltage is limited by the weakest component which is probably the cheesy little on off switch that come in our boxes.

If it were being used when a low amperage switch had to be used that would be something. If that is what you are doing then it probably does work a little better.

Actually what you are doing is kind of cool. If I had room I would steal that to redo one I made.

I'll have to look for that thread. Sounds like fun. If you know where it is how about pointing me at it.

Have fun!

 

[Wireguy]

Actually the next mod I am doing has plenty of room. Just not where I need to put the switch. HHMM. What was that part # again?

 

[Trebor]

Looks good. Do you know the Rds(on) of the FET at Id=1A? What is the number of the MOSFET? That looks like good Eagle work to me.

 

[Pendarus]

Yea I can understand that.



As far as the mosfet creating better vapor I don't buy it. A relay even if its a mosfet doesn't increase voltage. Unless it has a booster function built in. In this case the voltage is limited by the weakest component which is probably the cheesy little on off switch that come in our boxes.

If it were being used when a low amperage switch had to be used that would be something. If that is what you are doing then it probably does work a little better.



Have fun!

Thanks!

I read it some where that one builder "felt" he got better vapor with the mosfet. I can only assume some loss in the momentary switch that does not occur with a fully "on" mosfet. Like I said a feeling....

Looks good. Do you know the Rds(on) of the FET at Id=1A? What is the number of the MOSFET? That looks like good Eagle work to me.

Thanks as well! Just started using eagle a few days ago. I hope to have a PCB when I add the booster to make it all neat and tidy. I will see what mosfet I selected when my digikey order arrives tomorrow. I don't have it written down anywhere.

 

[caesar]

If it's fully on at a Vgs of 3V, has less then 100mOhm resistance and is good for 3A you have a winner there.

Integrated ESD body diode is highly recommended if you plan to touch that component without grounding yourself.

 

[j0ker]

The "mosfet more vapor" theory comes from the idea that the switches being used, most from Radio Shack, are not very efficient and have a loss.

 

[Pendarus]

Looks good. Do you know the Rds(on) of the FET at Id=1A? What is the number of the MOSFET? That looks like good Eagle work to me.

STP40NF03L 30V 40A

Rds 0.022Ω @ 20A

VGS(th) 2.5V Max

I'm not sure about the Rds whats a good range?

 

[Trebor]

That's a good value for Rds. The curves only show the value for a Vds of 10v but it should still be good for 5v. Thanks for the info. BTW, the Rds is the resistance of the FET when it is turned on. So you want it to be very low in comparison to the resistance of the atty. In the case of a 2.5 ohm atty, the resistance of the FET is very small when compared to the atty.
So give it a shot!!

 

[Wagex]

are nicosticks really that awesome? if thats the case i need to make one

 

[Pendarus]

That's a good value for Rds. The curves only show the value for a Vds of 10v but it should still be good for 5v. Thanks for the info. BTW, the Rds is the resistance of the FET when it is turned on. So you want it to be very low in comparison to the resistance of the atty. In the case of a 2.5 ohm atty, the resistance of the FET is very small when compared to the atty.
So give it a shot!!

Well after many delays, I finally got around to building it!

Looks good, makes great vapor! Only problem the Mosfet seems to be stuck "on". I noticed during my first test the flavor got nasty. I pulled the cart and could see the atty glowing and the button was not depressed!

I did some tests and as soon as I switch on the box, the atty starts to heat up. I know it's not the momentary switch because the LED is not lit, and it's powered by the momentary switch.

So I assume the Mosfet is bad. Do they fail "on". I would assume if it failed it would be "off". Any ideas would be appreciated, I would hate to have to replace the Mosfet. It would require a full rebuild of the box.

 

[Kewtsquirrel]

Did you put a high ohm resistor from the gate to ground? If you don't you'll get a floating gate and the mosfet will stay in that on position.

If you did, it's possible for mosfets to get stuck in the on position if you apply the incorrect polarity to them, did you ever put your battery in backwards?

 

[Pendarus]

Did you put a high ohm resistor from the gate to ground? If you don't you'll get a floating gate and the mosfet will stay in that on position.

If you did, it's possible for mosfets to get stuck in the on position if you apply the incorrect polarity to them, did you ever put your battery in backwards?

Nerf to the rescue!

No I did not put a resistor from the gate to the ground. Also I assume that the source would be the "positive" side and the drain is the "negative" side. Battery has never been in backwards.

I have some 470 ohm resistors for the LED. Would that work?


Photos:

 

[Kewtsquirrel]

They might, but you've got the mosfet backwards, and theres a chance it may have fried already. Source is ground, Drain is positive, and the gate is wired directly from the battery with a resistor wired to ground from the leg that is wired to the gate.

I would pull the mosfet to be on the safe side, they're pretty temperamental.

Also, you should wire it so positive goes -through- the atomizer before you attach it to the drain, if you go positive->drain->atomizer, you'll get a noticeable voltage drop that you won't get if you wire it positive->connector outside->connector inside->drain.

One of these days I'll actually make a writeup on the proper installation of em.

Edit: Resistor from gate to ground should ideally be several thousand ohms, 1/8th watt 10k ohms are cheap and plentiful, got a fry's nearby?

 

[Pendarus]

They might, but you've got the mosfet backwards, and theres a chance it may have fried already. Source is ground, Drain is positive, and the gate is wired directly from the battery with a resistor wired to ground from the leg that is wired to the gate.

I would pull the mosfet to be on the safe side, they're pretty temperamental.

Also, you should wire it so positive goes -through- the atomizer before you attach it to the drain, if you go positive->drain->atomizer, you'll get a noticeable voltage drop that you won't get if you wire it positive->connector outside->connector inside->drain.

One of these days I'll actually make a writeup on the proper installation of em.

Edit: Resistor from gate to ground should ideally be several thousand ohms, 1/8th watt 10k ohms are cheap and plentiful, got a fry's nearby?

Well crap! I have a Rat Shack and a Fry's.

I do have the mosfet between the atty and the negative side of the battery, but obviously wired wrong. I assumed "drain" meant "ground". I should read the tutorials better.


Also I have the center as my positive on the atty connector, is this wrong?



Thanks! Your help is much appreciated.

 

[Kewtsquirrel]

It doesn't matter if you have the positive wire to the outside or inside of the connector, just as long as you've got the other wire going to the drain. Don't feel too bad about thinking the drain was negative either, I did the same thing at first.

 

[Pendarus]

It doesn't matter if you have the positive wire to the outside or inside of the connector, just as long as you've got the other wire going to the drain. Don't feel too bad about thinking the drain was negative either, I did the same thing at first.

Thanks! Made the changes and it works! You da man!