901 atomizer disassembly

[kinabaloo]

mogur - Very interesting info about the Nickel alloy foam - great research

The current to reach 200C will be a lot less than to reach 400C, so if the current is set to only enough to reach 200C it will take longer to reach it - because it takes time for the heat to build up due to the heat capacity of the wire. Ok, it's still pretty quick, but might be noticeable, say 1 second.

Yes, a constant current circuit could be made with an op amp (comparator) and mosfet that looks similar to my circuit. But that would be using the op amp in an analog way. My circuit is intially just on, then behaves like PCM once the oerational temperature is reached; the op-amp is hard-on or hard-off.

[mogur]

Yes, and that is the beauty of your circuit. I wasn't putting it down. And if it can discriminate the resistance change reliably, the circuit is bang on.

But to defend constant current supplies, I have to say that they would not restrict current in any way until the set temperature is reached. Why would it slow anything down? Both circuits would throw full voltage at the element until it reaches equilibrium. Why would it take longer due to the heat capacity of the heater element? Both circuits are obviously limited by that factor. Your circuit throws full battery voltage at it until it reaches temperature, then it cycles on and off to keep the temperature up. Mine would throw full voltage at it until it reaches temperature, also, then reduces voltage to keep the temperature up. The only difference is that your circuit monitors the small changes in resistance of the heater wire as it heats up. Mine only depends on a current determining resistor, located inside the battery compartment. Both need to be calibrated once.

[kinabaloo]

Yes, and that is the beauty of your circuit. I wasn't putting it down. And if it can discriminate the resistance change reliably, the circuit is bang on.

But to defend constant current supplies, I have to say that they would not restrict current in any way until the set temperature is reached. Why would it slow anything down? Both circuits would throw full voltage at the element until it reaches equilibrium. Why would it take longer due to the heat capacity of the heater element? Both circuits are obviously limited by that factor. Your circuit throws full battery voltage at it until it reaches temperature, then it cycles on and off to keep the temperature up. Mine would throw full voltage at it until it reaches temperature, also, then reduces voltage to keep the temperature up. The only difference is that your circuit monitors the small changes in resistance of the heater wire as it heats up. Mine only depends on a current determining resistor, located inside the battery compartment. Both need to be calibrated once.

The current you choose will be lower than normal so the coil will take longer to heat up. Or it will switch from full current to lower current somehow?

[mogur]

The current you choose will be lower than normal so the coil will take longer to heat up. Or it will switch from full current to lower current somehow?

Okay, you win this one, but I'll get you next time, grin.

[kinabaloo]

Okay, you win this one, but I'll get you next time, grin.

A constant voltage supply circuit for the atty is a good idea for simply maintaining atomiser performance for a certain period. But requires a higher voltage battery pack to start with so probably not worthwhile when traded with increased size in devices where smallness is desirable.



Luckily my temp. control circuit also behaves in such a way as to provide the feature of counteracting diminishing battery power. And I might not have explicitly realised that without this discussion

[Tom09]

Will be interested if any tin in this alloy; wrt tin found in deposit.

Oh yes, the source of tin is a very important point! If the mesh material would become confirmed to be Ni, it could more likely be excluded to provide a possible source of tin. State of the art in nickel foam production appears to be the chemical vapor deposition route (lower tech facilities might still be in production, though). This makes use of a chemical transport process that is also known from nickel refinery (Mond process). Therefore, the mesh can be expected to be of very high purity (INCO Foam commercial brand claims 99.9% Ni, for instance).
I took some time to read up the various posts on solder corrosion. I couldn’t find if there has been a definitive answer on the actual solder composition. Maybe Exogenesis could perhaps remind to dedicate an additional analyses on a solder blob to address the discomforting problem of metal mobilization. Not that I would really worry about tin (not hazardous), but reserve concerns about what unknowns do occur in the tin-bearing alloy that could become dissolved with it.

[kinabaloo]

Oh yes, the source of tin is a very important point! If the mesh material would become confirmed to be Ni, it could more likely be excluded to provide a possible source of tin. State of the art in nickel foam production appears to be the chemical vapor deposition route (lower tech facilities might still be in production, though). This makes use of a chemical transport process that is also known from nickel refinery (Mond process). Therefore, the mesh can be expected to be of very high purity (INCO Foam commercial brand claims 99.9% Ni, for instance).
I took some time to read up the various posts on solder corrosion. I couldn’t find if there has been a definitive answer on the actual solder composition. Maybe Exogenesis could perhaps remind to dedicate an additional analyses on a solder blob to address the discomforting problem of metal mobilization. Not that I would really worry about tin (not hazardous), but reserve concerns about what unknowns do occur in the tin-bearing alloy that could become dissolved with it.

Tin has no role in our biochemistry (and metal form would probably be unmetabolizable anyway; it might work as an oxidising catalyst. And as we are talking about possible particles in nano size, some of whch might become inhaled into the lung where they might stay for a considerable time, it is of some concern I think. Tin is a common contact allergen.

The juice is greater contact with the metal foam. But at the point of contact the solder joint alloy will get pretty hot; either could be the source (it is unlikely to have originated in the juice). Common 'lead-free' solder: 96% Tin 4% Silver.

[exogenesis]

Didn't see your last post Tom09

I'll add the solder blobs to the analysis list, also will compare
some silver solder, ordinary solder & lead-free solder.

[kinabaloo]

Didn't see your last post Tom09

I'll add the solder blobs to the analysis list, also will compare
some silver solder, ordinary solder & lead-free solder.

That will tell us which solder is used; my money is on lead-free r.t. silver.

The main interest ten is whether the metal foam contains any tin. Some say the mayerial is steel but I think it will be nickel, possibly alloyed with tin.

Of course, both might be the source.

Some time ago smeone mentioned the phenomena of spontaneous growths of fine threads from metals and it might be these, having broken free, that is the mechabism for the tin getting into the deposit. An alternative I think is some electrolysis (or at least electochemical action). Or simply the juice chemically acting on the allot of either the solder of foam (in the case of the solder, possibly via the flux).

Look forward to the results Exo ...

[exogenesis]

Fairly sure the solder will have no lead in it, certainly tin tho.

Also bear in mind that the XPS analysis of carbon-gunk that showed high tin levels
was 'surface only' analysis.
Meaning that it's possible the tin is only at the surface, rather than in the bulk.

I'd guess that it is probably uniform-ish through the mass though,
at some point I'll etch into a carbon mass to see the formulation changes with depth.

And for perspective : tin was 'only' 2.3% of the total gunk mass of about 20 mg,
(the total mass was only about 1000th of the mass of e-liquid 'vaped')

So that equals 0.5mg tin, & each of the 2 solder blobs must be around 4 mg,
so roughly 10% of the solder blob's tin mass ends up in a really gunked coil.
(20+ ml vaped, without cleaning).

-actually now I work it out, it still sounds quite a high proportion of the tin available.

But I'm thinking that you lose more of the solder than that to burn-clean cycles.
(judging from close examination of a multiply-heated test-coil)