Building a Homemade Atomizer
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It looks like this topic has died, but I think it has enough merit to breath some life back into it.
When I started looking into this, I was thinking a ptc (positive temperature coefficient) ceramic element was the answer. Now I think that's overkill.
Here's where I'm at now, and I welcome any advice or feedback:
A small nichrome wire loop (30-35 gauge) could be heated with a standard 9v battery. Temperatures well in excess of 300F could easily be achieved depending on the current/resistance tuning, a small nichrome loop could reach that temperature using less than 15mA draw from the battery. The 9v should have enough juice (~500mAh) to power the thing for 30 hours or more.
As loosely specced above, the nichrome loop would probably be underpowered for heating a cartridge (and wouldn't survive being jammed up against a cartridge anyway) but would be ideal for heating 2-4 drops of liquid quickly and efficiently.
If done with any competence at all, this should give us an "atomizer" that's suitable for dripping and can be replaced in about 5 minutes at a cost of less than 10 cents.
Anyone interested in contributing thoughts/ideas?
Something I could use some help with is thinking up an appropriate housing for this homemade atomizer.
When I started looking into this, I was thinking a ptc (positive temperature coefficient) ceramic element was the answer. Now I think that's overkill.
Here's where I'm at now, and I welcome any advice or feedback:
A small nichrome wire loop (30-35 gauge) could be heated with a standard 9v battery. Temperatures well in excess of 300F could easily be achieved depending on the current/resistance tuning, a small nichrome loop could reach that temperature using less than 15mA draw from the battery. The 9v should have enough juice (~500mAh) to power the thing for 30 hours or more.
As loosely specced above, the nichrome loop would probably be underpowered for heating a cartridge (and wouldn't survive being jammed up against a cartridge anyway) but would be ideal for heating 2-4 drops of liquid quickly and efficiently.
If done with any competence at all, this should give us an "atomizer" that's suitable for dripping and can be replaced in about 5 minutes at a cost of less than 10 cents.
Anyone interested in contributing thoughts/ideas?
Something I could use some help with is thinking up an appropriate housing for this homemade atomizer.
I am very interested in this, please don't drop it.
soon, I foresee, e-cigs will be banned in most of the countries, or/until the tobacco/farma companies will get a monopoly on it. Then it won't be as easy as now to buy it or the costs will be even higher than for smoking.
now back on topic
ptcs are great but I doubt they are available/affordable in small quantities. leave them for the next gen of e-cig producers
soon, I foresee, e-cigs will be banned in most of the countries, or/until the tobacco/farma companies will get a monopoly on it. Then it won't be as easy as now to buy it or the costs will be even higher than for smoking.
now back on topic
ptcs are great but I doubt they are available/affordable in small quantities. leave them for the next gen of e-cig producers
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Interesting ideas, but...
I wonder if the math holds up. What you're trying to acheive here, is not very different to dripping in a conventional e-cig, i.e. putting a couple of drops on the atomizer and then smoking till it dries out.
Your wire loop is drawing about 140mW of power. I found some data on a dutch forum indicating that a mini e-cig will draw about 0.9 Amps from the standard 3.6V Lithium battery. That would give a ballpark figure of 3 Watts.
The mini may be wasting a lot of power when used in dripping mode, but i would think that 140mW is a bit on the low side to boil/evaporate any meaningful amount of fluid.
Thoughts/sentiments/ideas and criticism is welcomed
yes, the power needed should be calculated on the basis of the quantity of the liquid to be vaporised.
The current loops have about 3.5 W to get to 290 deg C
Making the wire loop to heat just enough to vaporize the liquid would be great - it will draw less power, so more life for your batt - and it won't burn the liquid.
The current loops have about 3.5 W to get to 290 deg C
Making the wire loop to heat just enough to vaporize the liquid would be great - it will draw less power, so more life for your batt - and it won't burn the liquid.
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I started in on the math, trying to figure out how many joules it takes to boil a drop of e-liquid, guesstimating at the boiling temp and volume then realized it would be tons more fun just to give it a whack. I'll order some nichrome off of ebay and see if I can't fry up some nicotine.
Heading off for vacation next week so I probably won't have anything to report for a bit.
I did some watt calculations on two types of atomizers.
View attachment atomizer.zip
Type 1 has lots of problems so I'm dropping that plan. Resistance is really low and wires joining on both sides would make such a big pile that the whole thing would shortcircuit. Type 2 looks good at least on paper.
With 1 cm diameter, 3.6 volts, 33 ohm/m 0.274mm diameter wire and 32 side turns, it would spouf around 3 watts. Assuming my calculations are correct of course There are some errors in calculations but probably not very significant.
Quick calculation suggests that 46% of surface area would be covered in wire.
0.8mm atomizer would fill 58% and produce ~3.6 watts.
Finding suitable material where to assemble this is the main problem I think.
0.3-0.4 mm CNC drill bits should do.
Octave/matlab code follows:
View attachment atomizer.zip
Type 1 has lots of problems so I'm dropping that plan. Resistance is really low and wires joining on both sides would make such a big pile that the whole thing would shortcircuit. Type 2 looks good at least on paper.
With 1 cm diameter, 3.6 volts, 33 ohm/m 0.274mm diameter wire and 32 side turns, it would spouf around 3 watts. Assuming my calculations are correct of course
There are some errors in calculations but probably not very significant. Quick calculation suggests that 46% of surface area would be covered in wire.
0.8mm atomizer would fill 58% and produce ~3.6 watts.
Finding suitable material where to assemble this is the main problem I think.
0.3-0.4 mm CNC drill bits should do.
Octave/matlab code follows:
Code:
# d = diameter(as cm)
# wire_resistance_per_meter (ohms)
# type 1
# parameters
volts = 1.5
#volts = 3.2
wire_resistance_per_meter = 50
#wire_resistance_per_meter = 33
#wire_resistance_per_meter = 4.4
side_turns = 16
d = 1.2
wire_resistance = 1/( (side_turns) * (1/(wire_resistance_per_meter/100*d)))
wire_current = volts / wire_resistance
wire_watts = volts * wire_current
wire_len = d * side_turns
# type 2
# parameters
#volts = 1.5
volts = 3.6
#wire_resistance_per_meter = 50
wire_resistance_per_meter = 33
#wire_resistance_per_meter = 4.4
side_turns = 32
d = 0.8
#d = 1.0
wire_diameter = 0.274 / 10
wire_len = 0;
r = d/2;
increment_as_mm = r/(side_turns/4)*10
# let i go from r to 0 in -r/(side_turns/4) increments
# FIXME: distances between side turn points aren't really fixed since they lie on a circle
for i = r:-r/(side_turns/4):0
# using pythagorean theorem
# FIXME: this doesn't apply to every second wire
wire_len += sqrt(r^2 - i^2) * 2;
end
#only calculated half
wire_len *= 2;
wire_len
wire_resistance = wire_resistance_per_meter/100*wire_len
wire_current = volts / wire_resistance
wire_watts = volts * wire_current
surface_cover = (wire_len*wire_diameter) / (pi*r^2)freepatentsonline.com/y2006/0196518.html for your amusement. Register and login to see figures. Guess you don't have to pay these guys if you want to make an e-cig...
Have you considered kevlar as a wick material?
It has high fire-, mechanical- and electrical resistance, it does not react with chemicals, and is relatively cheap in sports shops (in such a small quantity). It is even used as a wick is some applications...
The idea would be this:
The shaft of a long (but thin) metal screw projecting into the cartridge could be fully covered by a kevlar string. The heating wire could then be wound over a part of the shaft (that is covered by kevlar). The whole thing might also get a "collar" (made of kevlar?), that guides surplus e-liquid to the shaft, rather than letting it flow through the atomiser.
As for heating wires: when I could not buy resistance wire with the required ohm/m value, I used to unwound some turns from wirewound resistors. I know it is a dirty workaround, but it may work...
I plan to revive some dead atomisers using these materials in my hollidays. I wish I succeed. Atomisers are expensive here, and die one after the other.
It has high fire-, mechanical- and electrical resistance, it does not react with chemicals, and is relatively cheap in sports shops (in such a small quantity). It is even used as a wick is some applications...
The idea would be this:
The shaft of a long (but thin) metal screw projecting into the cartridge could be fully covered by a kevlar string. The heating wire could then be wound over a part of the shaft (that is covered by kevlar). The whole thing might also get a "collar" (made of kevlar?), that guides surplus e-liquid to the shaft, rather than letting it flow through the atomiser.
As for heating wires: when I could not buy resistance wire with the required ohm/m value, I used to unwound some turns from wirewound resistors. I know it is a dirty workaround, but it may work...
I plan to revive some dead atomisers using these materials in my hollidays. I wish I succeed. Atomisers are expensive here, and die one after the other
.
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I have figured out a more simple "sandwich" design with kevlar, that I will try soon:
heating coil | <1cm kevlar disc | metal wires | cartridge filling material
- heating coil: is located inside the kevlar disc (i.e. the kevlar disc is pushed onto it)
- kevlar disc: is just made by cutting off less than a length of 10 mm from the end of a kevlar rope that can be bought in shops
- metal wires: these project into and "interconnect" the kevlar disc and the cartridge filling material, and hopefully convey the e-liquid between them
Here the kevlar disc would function as a wick that surrounds the heating coil. An atomiser of such a construction could probably be simple and easy to disassemble for cleaning, when necessary. It will hopefully work...
heating coil | <1cm kevlar disc | metal wires | cartridge filling material
- heating coil: is located inside the kevlar disc (i.e. the kevlar disc is pushed onto it)
- kevlar disc: is just made by cutting off less than a length of 10 mm from the end of a kevlar rope that can be bought in shops
- metal wires: these project into and "interconnect" the kevlar disc and the cartridge filling material, and hopefully convey the e-liquid between them
Here the kevlar disc would function as a wick that surrounds the heating coil. An atomiser of such a construction could probably be simple and easy to disassemble for cleaning, when necessary. It will hopefully work...
There is some discussion here about suitable materials for wicks for fire dancing equipment - Home of Poi lessons - How to make your own gear> Fire Poi> What to use as wick?
They seem to think that Kevlar degrades but glass fibre is more durable. I wouldn't like to try breathing fumes from degrading Kevlar.
Here's another discussion about wicks that you might be interested in - http://www.e-cigarette-forum.com/fo...anufacturers-suppliers-whats-my-atomizer.html
They seem to think that Kevlar degrades but glass fibre is more durable. I wouldn't like to try breathing fumes from degrading Kevlar.
Here's another discussion about wicks that you might be interested in - http://www.e-cigarette-forum.com/fo...anufacturers-suppliers-whats-my-atomizer.html
Thanks Kate, those are great links. I will read them through to find out at what temperature kevlar degrades.
Anyway, that degradation would not be a problem if it happened only over the working temperature of the heating coil or if it happened only on a long run (in which case the kevlar disk could be regularly replaced.)
I hope I will have time to do some experimentation at my workplace, since we are engaged in electrical safety testing, and have adequate equipment for temperature measurements and such.
Anyway, I think glass fibres should be avoided, as those are liable to break, and their small particles may be extremely dangerous when inhaled.
Edit:
Your first link provides this information: "KEVLAR ® begins to evaporate at 427degree Celsius (800 degree Fahrenheit). turns into a gas. "
So, kevlar may be OK, if the heating coil operates well below 400 degree Celsius. Experimentation can show if enough vapour can be produced under this temperature. I suppose the answer will be positive.
Edit2:
Propilene-glicol boiling point is 300 degree Celsius. Quite narrow working range for the heating coil: 300...400 degree Celsius. Besides, kevlar possibly emits gases in this temperature range, too
Edit3:
Other sources mention a boiling point between 170...190 degree celsius. That is much better. Kevlar may be more stable at that temperature.
Anyway, that degradation would not be a problem if it happened only over the working temperature of the heating coil or if it happened only on a long run (in which case the kevlar disk could be regularly replaced.)
I hope I will have time to do some experimentation at my workplace, since we are engaged in electrical safety testing, and have adequate equipment for temperature measurements and such.
Anyway, I think glass fibres should be avoided, as those are liable to break, and their small particles may be extremely dangerous when inhaled.
Edit:
Your first link provides this information: "KEVLAR ® begins to evaporate at 427degree Celsius (800 degree Fahrenheit). turns into a gas. "
So, kevlar may be OK, if the heating coil operates well below 400 degree Celsius. Experimentation can show if enough vapour can be produced under this temperature. I suppose the answer will be positive.
Edit2:
Propilene-glicol boiling point is 300 degree Celsius. Quite narrow working range for the heating coil: 300...400 degree Celsius. Besides, kevlar possibly emits gases in this temperature range, too
Edit3:
Other sources mention a boiling point between 170...190 degree celsius. That is much better. Kevlar may be more stable at that temperature.
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http://www.e-cigarette-forum.com/fo...rs-forum/2602-janty-thread-q-5.html#post43065
It might be Kevlar, it might not.
The main goal would be to make the heating coil more robust, so as to result in longer endurance.
I found that it is hardly achievable without increasing the heating current, if a common resistance wire is used for the heating coil. Those wires all have too high conductivity. Increasing the diameter of the wire to be more robust -> the length should be increased, too, to result in the same resistance -> consequently, the heated volume is also increased -> the current should be also increased to heat up the higher volume to the same temperature.
Because of this, common resistance wires might not be suitable for a more robust design, without increasing the heating current.
I found, however, that graphite heating foils have 300 times as high resistivity as metal alloys. So, a heating element made of graphite foil could be 300 times as robust (i.e. its cross-sectional area could be 12mm2 instead of the 0.04mm2 that is used presently.)
The problem is, that such graphite foils cannot be bought in shops. They can be ordered by appliance manufacturers, instead. So, it is up to the e-cig manufacturers to use them.
I found that it is hardly achievable without increasing the heating current, if a common resistance wire is used for the heating coil. Those wires all have too high conductivity. Increasing the diameter of the wire to be more robust -> the length should be increased, too, to result in the same resistance -> consequently, the heated volume is also increased -> the current should be also increased to heat up the higher volume to the same temperature.
Because of this, common resistance wires might not be suitable for a more robust design, without increasing the heating current.
I found, however, that graphite heating foils have 300 times as high resistivity as metal alloys. So, a heating element made of graphite foil could be 300 times as robust (i.e. its cross-sectional area could be 12mm2 instead of the 0.04mm2 that is used presently.)
The problem is, that such graphite foils cannot be bought in shops. They can be ordered by appliance manufacturers, instead. So, it is up to the e-cig manufacturers to use them.
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aaa - how about getting some graphite foil out of an old device?
Or how about experimenting with the graphite found in pencils?
Or how about experimenting with the graphite found in pencils?
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