DIY Electronic Cigarette

This project is currently being updated. Feel free to get your comments and suggestions in so that the feedback can be used in my next build.

There is a problem with the circuit. Please see the comment from Zanderist below. I have updated the schematic in the next step.

So when I wanted to quit smoking I tried an electronic cigarette. They were expensive and didn't produce enough vapor for me. I figured hey it can't be that hard and decided to look into making my own.

Approximate cost not counting batteries is about $12

I took my existing electronic cigarette and hooked it up to a voltmeter and started making notes. I found other electronic cigarette models that had variable voltages so I decided to search through several forums out there to see what range of voltages were being used.

I found that most operate off 5-8vdc with wattage being a little higher than just from the battery alone so battery voltage needs to be higher than what is being used and the amp hours need to be high.

I found that most electronic cigarette mods were using IMR 14500 3.5v Lithium Ion Batteries

Needing to control the voltage I looked at several voltage regulators and came up with the LM317 because it supports the volt range I'm working with. I also wanted to leave room for creating a desktop model.

Nicotine use in the US requires you to be 18 years of age or older but then again this project isn't about nicotine and I didn't use any when I really began to quit smoking.

Feel free to ask questions and/or make suggestions.

Step 1: Application Schematics & Math

Use the first schematic in this step. This update is from working with Zanderist. This was originally designed for the LM317 voltage regulator but after suggestions from Zanderist the design is now using LM338t. Other schematics are from my first design and manufacturer specs.

As far as the math goes I've done it for you so don't worry too much. I calculated the values based upon 7.5vdc but the intended use is around 6.5 to 7vdc. I left in the overhead because as the batteries get drained you can crank it up.

Step 2: Parts

Most parts can be found online. I bought some parts at radio shack but some parts didn't hold up on production models. The only difference here is the voltage regulator has been switched out with the LM338t.

In addition to the list in the image
Altoids tin
510 connector (atomizer screws on here) http://www.madvapes.com/prewired-510-battery-connector-sealed-3682.html
IMR 14500 3.5v Lithium Ion Batteries (red wrapped batteries that look like AA's)

Step 3: Inside, Prototype and Various Views

See image notes for more detail

Comments

[Zanderist]

Don't use the LM317 IC, its rated at 1.5 amps which is too low for this application.

It would be better with the LM338t, if keeping to this design layout.

However if choosing to use the LM317t you will need to use an additional power transistor (which you can also buy at radio shack) to increase the current output.

A quick google images yeilds the following results:

https://www.google.com/search?q=lm317t+increase+current&espv=210&es_sm=122&tbm=isch&imgil=853-qQRm6avh-M%253A%253Bhttps%253A%252F%252Fencrypted-tbn2.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcQpeG2hW_Yimcj4GH0PmIpz30fgfkOMvMd-DGCpgk4ojh9p1DXRUQ%253B400%253B218%253BiEw08L4XO6s4AM%253Bhttp%25253A%25252F%25252Fwww.reuk.co.uk%25252FLM317-High-Current-Voltage-Regulator.htm&source=iu&usg=__0_BJ-c6grb9Z8IisngXh64-Crrg%3D&sa=X&ei=pKLyUvDQL-fNsQT2-4CgDw&ved=0CD0Q9QEwAg&biw=1240&bih=642#facrc=_&imgrc=853-qQRm6avh-M%253A%3BiEw08L4XO6s4AM%3Bhttp%253A%252F%252Fwww.reuk.co.uk%252FOtherImages%252Flm317t-pnp-pass-transistor-voltage-regulator.jpg%3Bhttp%253A%252F%252Fwww.reuk.co.uk%252FLM317-High-Current-Voltage-Regulator.htm%3B400%3B218

[MrRedBeard]

Wow I stand corrected! I completely over looked this when I designed it. Knowing this now I can't believe it still works after a year of heavy use. I will have to build a version 3 with the LM338t. I have already been kicking around the idea of building a variable wattage version using a micro-controller.

7.5 vdc and 2 ohms = 3.75 amps

7.5 vdc and 1.5 ohm = 5 amps

Thanks for the feedback.

[William L.D]

From the LM317 Datasheet

Electrical Characteristics:

VI-VO = 5 V, IO = 0.5 A,

0°C ≤ TJ ≤ +125°C,

IMAX = 1.5 A,

PDMAX = 20 W, unless otherwise specified.

IO(MAX): (Maximum Output Current) :: TA = 25°C

VI - VO ≤ 15 V, PD ≤ PMAX MIN: 1.5A TYP: 2.2A

VI - VO ≤ 40 V, PD ≤ PMAX MIN: 1.5A TYP: 0.3A

Further More:

Description:

This monolithic integrated circuit is an adjustable 3-terminal

positive-voltage regulator designed to supply more

than 1.5 A of load current with an output voltage adjustable

over a 1.2 V to 37 V range. It employs internal current

limiting, thermal shutdown, and safe area

compensation.

Focus on line: "designed to supply more than 1.5 A of load current"

So, if you can keep the LM317 at 25°C (77°F)

You can supply at least 2.2A (maybe more) :: it really depens on the temperature coeffiecent

and the output current is internally limited (again accouring to the datasheet)

-- this is why it has been working for you

[William L.D]

The texas instruments datasheet says the current range is:
MIN: 1.5A TYP: 2.2A MAX: 3.4A
@7.5 vdc
You could use: a 2 ohm - 5 ohm coil
7.5/1.5A = 5 ohms
7.5/2.2A = ~3.41 ohms
7.5/3.4A = ~2.1 ohms
7.5/3.8A = ~2 ohms

[Zanderist]

You probably would only need a mircocontroller if you wanted a display. unless your going to try a PWM style of variable wattage.

I've been trying to reverse engineer the whole variable wattage thing to sorta debunk if its just a marketing gimmick.

Something variable wattage could be done pretty simply I suppose with something called a trans-conductance amplifier .

[MrRedBeard]

Well it's not entirely a gimmick. The wattage is what drives the heat so it gives you a more consistant vape. This is done by calculating the ohm rating of the carto quickly and then delivering the amount of voltage needed to create the amount of wattage desired.

Now I'm curious about doing variable wattage without a micro-controller. I'll take a look and see what I can find too then post my findings here.

[Zanderist]

I've already blazed a trail for you to follow into then, you've cleared up the vary wattage thing then.

What you have in the following image is a noninverting op amp driving a transistor in an emitter bias configuration. Nice thing about this is it takes a very small voltage to drive the opamp. The dc voltage source you see going into the op amp could be sub'd for a potentiometer set up to be a voltage divier. What it comes down to is the gain you choose at the op amp.

[MrRedBeard]

Oh ok cool! I think I may already have the parts. I'll look tomorrow and see.

[frmmm]

not sure what's going on; I made a prototype, connected variable power supply, set it for about 7V and after a while potentiometer burned, also voltage regulator was overheating like crazy... :(

[MrRedBeard]

Man that sucks. Do you have a picture of your setup and/or a list of your components?

[frmmm]

Sure thing. Two loose wires are V out and ground. I connected the power to power rail in right upper corner. Ignore the arduino on the left, as it was not connected to anything. In picture with parts, there should also be 1uF ceramic cap, which is present on picture ( yellowish element).
Thanks for reply.

[MrRedBeard]

Hard to tell from the image.

I just looked up the spec sheet via the site listed on the packaging and the pin out is the same.

Wait where is the 1st wire on the pot?
From left to right
1 should be VCC (I don't see a wire)
2 should be Out (appears to be wired to ground)
3 should be ground (your green wire from the pot should be direct to ground and you have it going to LM338t out)

I think you direct fed output voltage to the pot instead of controlling the amount of ground to the adjustment pin.

[frmmm]

Ah, that would also explain why voltage regulator whas overheating. I feel so stupid :) Thanks mate, Im gonna order new potentiometer and try it again. Thank You for support :)

[MrRedBeard]

No problem and don't feel stupid, I have burned up so many things.

[hansamann]

Hi MrRedBeard, really interesting project. I would like to create an arduino-controlled ecigarette voporizer, your project seems to come very close. What I am currently not quite understanding, probably due to the lack of knowledge about ecigarettes, is how the liquid is going through the tin and is then later somehow vaporized. Did I miss the part for that? Any tips/hints/links would really be appreciated.

thx for sharing!

[MrRedBeard]

Somehow I missed this comment. Did you ever get around to building it? I wouldn't mind taking a stab at an arduino based e-cig.

[whitsona]

Thanks for this, it's the best help I have found so far. My daughter is working in Arduino and wants to make her own version of the Tempesco-- it's a clear box that shows you what the weather outside by making it cloudy or rainy or other inside a closed, clear box. So, I was thinking that getting the atomizer working that you guys use in your vape things would be a good way to go. Since we don't vape, can you tell me-- are these atomizer parts supposed to be disposable?

[MrRedBeard]

Yes but they are fairly cheap to get especially for what you're doing. I've seen people make fog machines with them and its funny because that's where the technology came from in the first place.

[buddy4341]

Hi. I want to learn how to make a variable wattage device which goes up to at least 100 watts, maybe 150 watt, with a display and if possible temperature control like the latest box mods you can buy. If i can build these devices here in the United States and sell them at a competitive cost then i guarantee anyone doing this will get rich real quick.
Im not an electronic genius but im good at selling. Anyone want to help me figure out how to build these? Electronics tech needed

[MrRedBeard]

So a box that goes to 100 - 150 watts and can display possible temp. They are making these currently. It uses nickle wire and the controller reads back the temp. There is something about nickle that makes this possible. Just making a wild guess I imagine they measure the resistance and wattage before then use those values with operational resistance. I could design and build a prototype.