Temperature "stabilizer" for transformer soldering iron

yorgus_1978 wrote:

it would have to distinguish 0.1 from 0.2V every 10ms (max voltage).

Are you sure that you will get this 0.1V difference at the tip / ends of the secondary winding as the difference between the cold and hot tip (preferably around 300 * C +/- 20 * C) ????

yorgus_1978 wrote:

As for copper oxides - they are semiconductors,

Sulfides too? Moreover, due to the different thermal expansion (the screws are made of steel), the pressure will not be constant, so the resistance of the contact itself will change.

yorgus_1978 wrote:

the change between cold and warm is like between 125 and 175 mV.

And you are 100% sure that it will be a constant value for e.g. different tips? Different pressure of the tip to the flat bar?
I don't, and hence my posts.

398216 Usunięty wrote:

yorgus_1978 wrote:

it would have to distinguish 0.1 from 0.2V every 10ms (max voltage).

Are you sure that you will get this 0.1V difference at the tip / ends of the secondary winding as the difference between the cold and hot tip (preferably around 300 * C +/- 20 * C) ????

yorgus_1978 wrote:

As for copper oxides - they are semiconductors,

Sulfides too? Moreover, due to the different thermal expansion (the screws are made of steel), the pressure will not be constant, so the resistance of the contact itself will change.

yorgus_1978 wrote:

the change between cold and warm is like between 125 and 175 mV.

And you are 100% sure that it will be a constant value for e.g. different tips? Different pressure of the tip to the flat bar?
I don't, and hence my posts.

You can see from the oscilloscope picture attached above that the difference is 125-175 mV. As for the absolute value - after all I said it was a relative change - in this case 1.4x, which will be almost the same for any arrowhead. Besides, such a stabilizer, even with a nice +/- 20C accuracy, would be fine anyway. I do not have a soldering iron at hand that I could remake, if I had, I would play.
As for sulphides - this is what happened in metalworking with a black coating on copper (sulphate liver). Where are they normally supposed to come from between the tip and the flat bar? H2S is a poison with a strength similar to HCN, so I do not know who has such a concentration that the copper will sulphate.
One more thing - if someone does not want to measure on the screws, he can solder the voltage contacts to the tip. After all, it's half a minute of work. And then what will be wrong?

yorgus_1978 wrote:

Where are they normally supposed to come from between the tip and the flat bar?

From the air. If silver is covered with sulfide, why should copper be free from it?

yorgus_1978 wrote:

the difference is 125-175 mV.

Between room temperature and ... maximum? And I meant the difference between 280 and 300 or 300 and 320 * C.

yorgus_1978 wrote:

it is a relative change - 1.4x in this case, which will be almost the same for any arrowhead.

Relative value - possible. On the other hand, the voltage will be different for the 1.5mm2 tip and 8 for the 1.25mm2 tip (example only - it's about the difference in the diameter of the wire from which the tip is made. the "factory" cable there are slight deviations - it is not a coil wire where the diameter must be strictly monitored down to a hundredth of a millimeter).

yorgus_1978 wrote:

can solder voltage contacts to the tip.

And that's great! And the tin will know where to melt?
I know that you have come up with something and now you will prove at all costs that it is the best (because yours). On the other hand, I look at your idea from the side and having some experience and knowledge, I wonder (just wondering) how it would work in practice.
You have measured the resistance of the mainsail - one mainsail and only once. Replace the tip with another - less burnt because new - and repeat the measurement. After all, the transformer tip "dissolves" during operation (specifically in tin) and the operation of the fuse accelerates this process - after a few hours, the tip of the tip may thin out to such an extent that the resistance of the tip will change dramatically. I do not see the possibility of including this fact in the regulator.

Moderated By tmf:

@ yorgus1978 @ 398216usuniety - Gentlemen, instead of having a sterile discussion for another 100 posts, maybe my colleague @ yorgus1978 will present a prototype of the solution. Not only will it ultimately confirm or falsify the possibility of such a measurement, but it will also be an interesting structure worth describing on the electrode. As all the arguments for or against have already been raised, I do not see any need for further exchange of views on this subject, the more so as it is not related to the structure of the author of the topic presented here. Hence, I am asking for a separate topic if you consider it an important problem, or for presenting empirical data and construction.

yorgus_1978 wrote:

I just checked - the change between cold and hot is like 125 to 175 mV.

This is between cold and hot, and here it must be measured between hotter and less hot, i.e. in a temperature range of, for example, 320. . . 300 C.
By the way. I took the current measurements on the tip with a clamp meter. For my soldering iron (such a Russian in a bakelite housing - it is impossible to drive ) and it fluctuated as it warmed up - cooled within the soldering temperature limits by a few amps (average about 100A). Then I made an experimental current transformer made of a cut M8 washer, on which I wound a few dozen turns of wire, put it on the tip and finished the intersection. The voltage on this winding, rectified with a diode and filtered with a 100nF capacitor, ranged between 0.2 ... 0.3 V (0.6 V was probably taken by the diode).
Unfortunately, I do not have an oscilloscope, maybe someone will repeat my experiment and share the results ..
Maybe the measurement of the current on the primary winding would be easier, but it seems to me that the measurement on the mainsail, or rather on the mainsail rails, may be more reliable. Only now how to insert it into some driver? It is known that the measurement may or even certainly depends on the tip used, but here you could use a potentiometer in the controller to make corrections after replacing the tip, and even during operation, looking at the effects of soldering.