Rick's b.log - entry 2021/04/25

I got up late... (cat food)

Still... lots of guilt for not going and feeding the furballs at 7am when it was a much cooler 8°C.

Gourmet cat food.

When I went down, they were both yowling and howling because they wanted fed and sex and couldn't decide which one first.

Seeing the plate presented in front of them, the noise was replaced by a loud purring that reminded me of the cooling fan on my old PC.
Anna dived right in.

Anna appreciating the food.

Wawa appreciating the food.

I left both doors open, to see what would happen. I don't let them out much at the moment. In full heat, they both have a tendency to wander off. Often in opposite directions. Thankfully their calls of "I want babies! Screw me now! Anybody!" make them fairly easy to locate, but you have to go and get them as they have only one thought rattling around their tiny minds.
Plus... me being a convenient source of male hormones, I don't get any peace. The fact that I'm many times larger and a different species never seems to occur to them. "Me female, you male, good, let's ****" is about as far as it goes.

So it was a surprise to see that Wawa was the one who abandoned her food and came to find me.

"You and me, right?"

I walked her around the house. Twice. No sign of Anna. I went back down to the stables half expecting to see Anna tucking in to Wawa's food.
But, no, Anna understood that reindeer and wild boar food was special. She was eating it carefully and slowly.
Well, I'm glad somebody appreciates it.

Battery soldering iron

Battery soldering iron.

Well, ever wondered what's inside? My guess is a lithium battery, possibly one of those ones about the same sort of size as an AA cell (16000, 18000, or something, I forget the exact number) along with a controller that will handle battery charging and tip temperature. I know there's some sort of controller inside (rather than just a set of resistors and a comparator or two) because it's long hold on the button to turn it on, and short press to turn it off. There comes a point where a little microcontroller is cheaper than a pile of discrete logic.

The first surprise was that it used a weird screw to hold it together. No biggie, just means I need to break out the bigger kit.

Weird screws? Bring it on!

The second surprise was the tip itself is a screw in thing, akin to a little 3V lamp (if you ever played with those in your Tandy Electronics kit when you were younger?).

Replaceable tip.

I was not able to open the device fully because the tip end has a collar that is crimped in place. However, I could open it enough to peek inside.

First up, the battery.

Battery soldering iron.

Looking further down, we can see the little motherboard inside the body of the iron.

The main board, battery end.

The main board, tip end.

As for controlling things, I can't say about the battery charging. There doesn't appear to be any specific charger (either in the MCU or something like a TP4056) so it might be a simple current limiter/MOSFET - which would tie in with the A7sHB MOSFET connected between the DC +V and the battery +V.
As for the tip temperature (and, yes, it heats up in about twenty five seconds), it is possible that the resistance changes with temperature, so the MCU may be able to measure that by briefly switching the power off and routing a voltage through the ADC, or something. There are only two connections to the tip, so there's no thermistor to report the temperature.

Stupid prices on Amazon

How much for postage.

The price is for five packs, so the price of €26,39 is actually marginally more expensive than ordering five packs directly from tassimo.com. which will charge €24,95 for the same thing, along with a much less ridiculous €4,99 for postage. But, did you read the small print at the top of the page? Pop in a Cadbury Hot Chocolate and the total comes to €34,43. Add another Cadbury, and the total is now €33,94. How is this possible? Well, because with an order over €30, postage is free. So why not benefit and essentially get one pack of drinks free (plus it's a tiny bit cheaper).

Seven packs of drinks for your Tassimo and still a lot cheaper than that Amazon seller wanted for postage alone.
Oh, and it would get here this week, not next. Tassimo reckons 2-5 days.

Amazon... don't waste my time. Please, please include postage in "order by price".

PS: What's with this "NEW! EASIER TO MAKE" rubbish? It's a Tassimo capsule. You literally pop it into the machine and poke the button. Short of having somebody else pop it into the machine and poke the button, I fail to see how it could be made easier.

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David Pilling, 26th April 2021, 01:37

Soldering iron... looks like you're right about all that. Common to have no separate temp sensor, but to have built in thermocouple. You could measure the voltage. I will take away that I should try Bing when Google does not know, that surprised me. As to translation, Google docs can load PDFs and then there is a translate option.

Mick, 28th April 2021, 01:48

I don't like the fact the soldering iron has no proper on off switch. I wouldn't trust it not to come on by itself. Saving feature is the tip unscrews.

Rick, 28th April 2021, 17:26

That's a good observation, however I doubt that this thing is liable to turn itself on by accident, else we'd have warehouses and shops burning down (the tip gets to ~409°C in under half a minute, and it is packaged in plastic and cardboard).    That said, there's no "pull tab" or interlock, it's a surprise some idiot hasn't tried to turn one on in a shop. Just need to hold the button for three seconds, and within a few blinks of an eye, it's ready.    (I wonder how long the battery lasts?)

Rick, 28th April 2021, 17:33

David, looking online it seems that temperature controllable tips have three pin connections (power, ground, temp sense).    If this iron starts to wear out and gets replaced (don't hold your breath!), I'll strip it down and try to monitor what's actually happening. Is it sensing something somehow? Or maybe the tip is designed to "heat to this and then cut out"?    A very brief look inside suggests that the tip's positive is directly connected to the battery (P+ and B+). I didn't look for P-, at a guess it's perhaps routed via some sort of FET?

David Pilling, 29th April 2021, 12:54

Rick, see the circuit diagram of the Hakko T12 bit:    https://hackaday.io/project/94905-hakko-revenge/log/144548-h akko-t12-thermocouple-is-not-type-k    Two pins for power *and* temp sense, another pin for earthing the metal of the bit.    All variations exist, 5 wires (power +/-, temp sense +/-, earth) down to just 2 wires (power and temp sense +/-).    With combined power and temp sense they turn the power off and then measure the thermocouple output.    You should be able to measure the thermo voltage output. Stick the bit in a flame.    There's a whole world of worry about earthing the bit, if you do there's no possibility of static charge being passed on, but if you do there is the possibility of discharging what you solder to.    Then you get the cheap clones, which support the earth connection but then leave it disconnected inside the controller - along with supplying illegal UK plugs (no fuse).

David Pilling, 29th April 2021, 15:58

The earth connection on my soldering iron has a capacitor in it - presumably stopping me shorting anything to earth - DC that is, but allowing static discharge.  I've got quite a few soldering iron pages on my wiki.

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