A circuit for temperature control of the atomizer coil

[kinabaloo]

Good morning, modders. Found a table at Nichrome 60 (NiCr) Resistance Wire that alleviates some of the math-



These values don't quite match other NiCr TCRs I've seen, but it'll take some playing around, anyway. A place to start.

Thanks mogur - these tally with your earlier figures. So 4% increase - it's detectable

And no changes needed to atomizer with my design; no extra sensor connection needed. The control is all in the 'battery'/power supply.

[mogur]

The following chart only looks simple, but it was a real pain to construct. Anyway, hope it helps, kina. Kanthal 52 and 70 have as large a temperature coefficient as pure tungsten, but the resistance is so low that smaller diameter and/or longer wires would be needed. The thermal expansion of K52 looks low enough to possibly overcome the coil failures due to wire contraction over hardened juice residue. Could be something to look at, at least.

Stainless or NiCr40 might be a good compromise if you need a larger resistance change than NiCr60 affords, and don't want to deal with tiny wires.

Kanthal A looks interesting to me for wiring up an over-clocked atomizer- larger surface area at the same temp. Or maybe a smaller surface area coil would heat quicker/hotter. I think some bench runs are in order.




I'm ordering up a half dozen different sizes/types tomorrow, let me know if you want to try any of these, I could snip off a few feet.

[kinabaloo]

The following chart only looks simple, but it was a real pain to construct. Anyway, hope it helps, kina. Kanthal 52 and 70 have as large a temperature coefficient as pure tungsten, but the resistance is so low that smaller diameter and/or longer wires would be needed. The thermal expansion of K52 looks low enough to possibly overcome the coil failures due to wire contraction over hardened juice residue. Could be something to look at, at least.

Stainless or NiCr40 might be a good compromise if you need a larger resistance change than NiCr60 affords, and don't want to deal with tiny wires.

Kanthal A looks interesting to me for wiring up an over-clocked atomizer- larger surface area at the same temp. Or maybe a smaller surface area coil would heat quicker/hotter. I think some bench runs are in order.

I'm ordering up a half dozen different sizes/types tomorrow, let me know if you want to try any of these, I could snip off a few feet.

You are really looking into this very actively mogur; impressed!

I was trying to test the resistance of the metal foam today but my multimeter battery is too flat

Yes, coefficient of expansion would be an interesting factor. Doubt that wire any thinner than nichrome 60 would be practical though.

Tried heating the coil submerged - nogo. But if submerged then withdrawn, only takes a second or two to start producing fog. Out of curiosity I used 'facial toner' whch is about 60% water and 40% PG and to my surprise the col cleaned up after just a few tests; wasn't expecting that, thoug I did let it go red-hot a couple of times but only briefly.

[kinabaloo]

Now we have mods with far higher capacity batteries, I think it worth consdering the possibility of slightly beefier coils with enhanced performance.

Flattening the coil to get a wider target for the juice droplets might be useful too.

[Kewtsquirrel]

Mogur, whats your plan to attach the wire to the leads to create an atomizer, with the temperatures atomizers are generating won't most solder simply melt?

[mogur]

Mogur, whats your plan to attach the wire to the leads to create an atomizer, with the temperatures atomizers are generating won't most solder simply melt?

Sorry I missed this post until now. I'm waiting on a resistance wire shipment right now, some nichrome, balco, kanthal, nickel, and ribbon, so I will gain a little experience with that soon, and will post. As I understand it, if the coil wire is non-solderable, you just physically 'hook and crimp' the two wires together, and blob the solder around the copper lead, trapping the non-solderable wire within that glob. There are plating and etching options, also, to get the coil wire solderable. I think the temperature at the solder joint will be substantially below the melting point of solder, but I really don't know at this point.

With a thermocouple meter, a variable power supply, and coil wires coming my way, I am just biding my time (and googling my ass off), grin.

[mogur]

I was trying to test the resistance of the metal foam today but my multimeter battery is too flat

I get .1 ohm across 1" x .125" x .015" dry nickel foam, +/-.05 ohm.

[boxhead]

hey i used to make thermocouples when i did cold structual testing ( Hughes aircraft, Space and communcation div. i broke spacecraft, missles and f18 wings) by getting a 120 volt reostate, a carboon core from a d sized battey and by attching one end of the output to the carbon and the other to a alligtor clip, twist the two wires to be welded, pinch in the clip and touch to the carbon, adjusting reostate down till i got a little or big ball of welded metal, the reostate was about ten pounds and whent<?> from o volts to 160 volts.

[kinabaloo]

I get .1 ohm across 1" x .125" x .015" dry nickel foam, +/-.05 ohm.

Thanks mogur. My meter batt. not replaced yet as haven't had chance to go out. Was also wondering about the resistance of the juice (say 5mm gap) and also of the deposit material (if you have a nice chunk to examine).

ps: some interesting results by Exogenesis on the atomiser deconstruction thread.

[mogur]

Damn, I gave up my variac when I retired, and that's probably a good thing- I shouldn't be playing with 160vac in my senility.