Different types of motor
In an AC motor, the alternating current is dumped into the windings and the force of the current when it reaches its peak causes a magnetic field which... would cause the motor to hum, to vibrate gently. This is why single phase (as in most domestic household supplies) motors need two windings and a capacitor. The second winding is offset slightly from the first, and the capacitor stores the current as it reaches its peak and releases it as the current fades away. What this does is it effectively fakes a second phase that is slightly out of time compared to the first. This is enough to kick the motor into rotating.
AC motors can only rotate in one direction, which is determined by the way the primary and secondary windings are arranged. Motors that can run in both directions do so by effectively switching which set of windings is connected to the capacitor, in essence switching which is primary and which is secondary. This can only happen at lower speeds, as faster speeds require the secondary winding to be disconnected when it is up to speed. In this case, the secondary winding is only to get the motor started.
AC motor diagram.
Brushed DC motors, typically low voltage DC motors, work by having the windings on the rotor (the part that turns) and carbon brushes resting against the metal contacts on the spindle to transfer power to the windings. Only one set of windings is energised at a time, and this causes the rotor to turn which switches to the other set of windings. The main problem with these sorts of motors is lower torque, due in part to lesser efficiency because of the brushes. Additionally because the brushes are in constant contact with the rotor, they wear. Sparking and overheating are potential problems, which is why brushed DC motors are rarely used in higher power/higher current applications. These motors are self-starting and don't need any additional windings to get going.
(Brushed) DC motor diagram.
BLDC, on the other hands, just needs to have three sets of windings - one for each phase - though note that internally they're probably quite a bit more complex, there won't be just three poles. Instead the windings may be split up and distributed through the motor body. Twelve poles, for example, treated as three groups of four. In order to make the motor turn, two of the windings are energised, and which two changes rapidly in order to create the necessary magnetic fields.
The control method is a lot more complex, however by being able to adjust the timing of when current is dumped into the windings, and which windings are energised at any given moment, and by how much power, it is possible to run the motor in either direction and at practically any speed supported by the motor.
Brushless DC motor diagram.
The final type of motor is a synchronous AC motor that runs on three-phase. This is very similar in design to the BLDC motor, however all three windings are energised. They are self-starting as the power on each phase is 120° out of phase (that means each phase reaches its peak at a different time compared to the others). They can only turn in one direction. Directionality is controlled by switching which windings are connected to which phases, and speed is controlled by clipping how much power is actually put into the windings.
Making a washing machine smarter
The above bit about motors was because knowing the different types helps to explain why modern machines use BLDC motors. As it turns out, there are many more benefits to having a BLDC motor in a washing machine. The acronym means BrushLess Direct Current, which is like a three-phase motor that runs on DC.
The benefits of having this type of motor, as opposed to a regular AC motor, are that they're more powerful for their size (which means a BLDC motor can be smaller than a comparable AC one), more efficient, and obviously a lot less mechanically complicated.
By way of example, my old washing machine had four sets of windings. The primary fast spin winding, the secondary fast spin winding to get it started (along with a centrifugal switch to disconnect the secondary winding when up to speed), along the primary and secondary slow spin windings. Due to the slow speed and torque, not only was the secondary winding never disconnected, but by switching which was the primary and secondary could control which way the motor turned.
The broken washing machine in the shed, that came over from the UK way back when, has a chunky motor with nine wires going into it, as it supports not only bi-directional slow speed rotation, but two 'fast' speeds. And, really, that's about all you're likely to find on a washing machine using AC motors.
A three speed AC washing machine motor.
Now, as it turns out, there is an unexpected benefit to using a BLDC motor. Since it only uses two windings at any given moment, this means there is an unused winding.
Since it is a DC motor, there will be some amount of current induced in the unused winding, in much the same way that spinning a brushed DC motor will generate power.
While the control method is complex as the windings switch around very rapidly, you can determine a number of things just by analysing the current induced in the non-powered winding and using this information alongside the motor's tachometer.
Determining the weight of the load - spin up the motor to a known low speed. Use the tachometer to monitor how long it takes to reach its speed. This will tell you how long it took, which relates to how heavy the drum is, which tells you the weight of the load. A sensing machine will do a number of short slow spins prior to filling the machine with water in order to weigh the load.
This can be used to control how much water goes into the machine. There's no need to fill to a full 6kg load amount when there's only 1.5kg of stuff to be washed.
Determining the fabric type and when there's enough water - typically such a washing machine will rotate continuously during the filling phase. The fin inside the drum will agitate the clothing, and as the fabric tumbles down from the fin to the bottom of the drum it will make a mechanical shock which will shake the drum. This action can be detected by the motor as the shock briefly alters the load on the motor.
Now, in the beginning there won't be much in the way of shocks because the drum will be tossing dry clothing around. As the water fills, the clothing will start to get wet and the shocks will increase as you're now tossing damp, then wet, clothes around. After a while, the shocks will start to decrease with means the clothes are now not only fully waterlogged but are now being dropped into water rather than on to a mostly bare drum. This is the point when filling can stop, and the relationship between the timing of all of these events can be used to work out what sort of fabric is in the machine. No, it can't tell it's a polyester skirt and a cotton blouse, but it can tell if it is mostly synthetics (which don't absorb much) or natural fibres (which do). I would imagine a fair number of people are like me and just put everything in together, so maybe it is best to think of this less as a "fabric" test and more as an "absorbency" test.
Note, in the absence of any clothing at all, the paddles will have an effect on the water in the drum that can be detected, and this may well be a special mode that the machine uses if it doesn't detect any weight. In this way, the machine can still behave in a reasonably sensible manner in the absence of clothing. Why would this occur? Well, my machine says you should run it empty on a 90°C cycle once in a while to keep the insides clean.
Performing the most effective wash - you might have noticed that newer smarter washing machines are noisy things. This is not only because of the plastic drum, but also because the most effective wash is one that really agitates the clothing. In the old days, the slow-spin just worked at a fixed rate with the drum a little under half full and stuff would just be rotated in the water.
As it turns out, that's not actually particularly effective. Better than hand washing, sure, but we can do better.
Better is only having a couple of inches of water in the drum, and altering the speed of the drum to cause the maximum amount of agitation of the clothing. This can be detected as how much the clothing 'slaps' into the water as it is flipped off of the paddle, hence the noise.
Chunky paddles to toss the clothes around.
Determining load balancing - something that plagued older washing machines, and may have been a factor in the demise of my previous one, is that when it comes to doing the fast spin, the machine would typically begin with a slow spin and then kick up to fast. If the load was not balanced, which is actually quite normal, the machine would vibrate. I don't think any of you realise how much a machine could vibrate because the machines use huge blocks of concrete as dampers, suffice to say that spinning a drum with maybe eight to ten kilograms (a 4kg load of sopping clothes) at six to eight rotations per second can be quite violent. We all know of the trope of the washing machine that walks itself across the floor, but I bet if you took a side panel off so you can see what's actually happening inside, you'd scream and run. There's a reason for the concrete and massive springs.
A smarter washing machine will spin the load at a rate just slightly faster than the wash spin (say, maybe 60 rpm or so) which isn't enough to cause mechanical damage but is enough to ensure the clothing stays stuck to the sides of the drum rather than being tumbled around. If the washing is out of balance, then this can be detected in the load on the drum as it won't be spinning evenly. If the machine thinks that the load is unbalanced, then it will stop and toss the clothes back and forth for a while before trying again. If the load is balanced, it'll go up to an intermediate spin, maybe 400rpm or so. If the load is out of balance at higher speeds, this can be quickly detected so the spin can be aborted and the load rebalanced.
But, why might a load that seems balanced at 60rpm become unbalanced at 400? Well, the slow speed balancing is full of water. As you go up in speed, a lot of water will be flung out and the material weights will start to come into play. If it's still good, then it'll go a little faster. It will eventually reach its maximum speed (typically 1,000 or 1,200rpm) but it will not just try to kick a sodden load directly up to high speed, it'll work up to maximum, such as that by the time you get there the clothes will probably be about as dry as they're going to get and the burst of top speed is to push out the very last drops that it can.
Suffice to say, modern washing machines can be given a lot of smarts without needing all sorts of sensors. Sensors, I should add, that would need to tolerate wide temperature variations, mechanical vibration, and being wet.
As such, my new machine really only needs a water level pressure sensor as a backup, the motor, and the temperature sensor. Unlike the older washing machines that had a temperature sensor to click off at a given temperature (usually as a safety to prevent boiling), and would instead heat by running the heater for specific time durations, the modern machine uses a thermistor so the target temperature can be targetted within a degree or two. I want my clothes washed at 40°C, it comes out at 38°C (which would be forty plus a few minutes of agitation without any more heating).
Temperature sensor (by the heating element).
One final thing to consider, you've probably heard that there are machines that can tell how dirty your clothes are. If your machine does this, it's likely performed optically by having an infra-red light shining across a gap to a sensor. How much of that light makes it across can be used to judge how many particles are in the water, as the dirt particles will diffuse the light. How it works isn't that different to the way they check car exhaust pollution levels. Mine doesn't do this as every feature, even if it's a €5 part, adds a fair bit to the price and my machine is the basic model. Basic enough that it has a lamp on top for ACP (Arrête Cuve Plein) but no actual way of getting the machine to pause before going into spin mode (this is typically used to remove delicates in a mixed load prior to doing the spin with everything else).
Mowing
Amazingly I managed to get the mowing done yesterday.
Why amazingly? Because this is what I saw on the way home. I don't live under that scary cloud, but I live in that direction...
Well, this doesn't look good.
Once I had the mower going, my first job was to get the driveway cut. If nothing else, that needed done. I put on a raincoat just in case (mostly to protect my noise cancelling headphones).
This is what I saw.
Yikes!
When I got back, I cleared everything out of the shed by the door (where I'd parked the buggy-thing that had the battery and jump leads) so if the heavens opened I could disengage the cutting deck, shift up to fourth, and leg it into the shed. I also unplugged the Livebox.
The Northern passageway got cut. This was followed by the Western Wilderness. I was keeping a careful eye on things as there was a lot of lightning by now. It was about half six in the evening and I didn't need sunglasses. In fact, at times I could see things being lit by the LED bar on the front of the mower. I expected to get wet at any moment.
After the Western Wilderness, I dropped the engine speed to low and then topped up the tank with the engine still running. Luckily it was quite windy by now so no worries about fuel vapour combusting. It was that sharp wind you get prior to thunderstorms. I glanced up. Black sky. Yup, check.
I cut the buttercups and daisies that I left last time as it was a spindly mess by now, then I headed to do the Southern patch (by the potatoes), then the Potager. The Potager, due to its layout, was a bit of a faff.
Finally, deciding I had enough petrol, and 25 minutes until the 8pm silence time, I went and did the Picnic Lawn that was also a mess of buttercups (I didn't mean to leave it last time but I stalled the mower on a big clump and decided "sod it, this is good enough, I'm done").
Five to eight, the grass had been cut and astonishingly while there were a few scattered raindrops, all that nasty black went and dumped itself on somebody else.
Ants
Last Saturday I was strimming and I noticed that there was a worryingly large chain of ants rising up the back of the kitchen and up into the loft. It's not a place I look for ants as they don't normally come up that way.
No worries, I have some ant gel in a little syringe. A few drops of that and they'll soon be gone.
Gel bait for ants.
On Sunday I went and looked and... they were walking around it. So I noted their paths and put down some new drops. They walked into it, poked around, then made a line around it. What?.
Sunday evening, still ants. So I sprayed the wall (except for the bait) with white vinegar. They weren't happy, but they walked through the vinegar. What the hell?
That Monday I had a dentist appointment at quarter past six. So I stopped at my local supermarket and... nothing. Empty cartons. There must be a big ant problem this year. All that remained was one pack of powder and an aerosol spray. I got those as better than nothing.
When I got to where my dentist is, I noted that I had made good time so I swung by the supermarket in that town. A small one, but it had a different sort of gel and a bait trap, so I got those.
Shit just got real.
I probably spent a good twenty euros on stuff to deal with the ants. When I got home I stopped the car beside that bit of wall, grabbed my shopping bag and got out.
"Okay you six-legged bastards, this is war!"
...
"Uh, hello? Hello?"
Not an ant to be seen.
Well, okay, I now have plenty of products to deal with ants, when they try coming back. While the spray and powder are mostly polite suggestions to get lost, the gel and trap are designed to destroy the nest by poisoning the queen. Better yet, they're not based on the same chemicals which mean the ants shouldn't be able to build immunity.
The syringe gel is based upon Imidaclopride, S-Methoprene, and a bit of Bitrex in case children try eating it.
The other gel is based upon Chrysanthemum cinerariaefolium extract. I suspect the EU rules on biocides have made this change, as it was the product that I used to use and I think it was based upon Fipronil.
The bait trap is based upon Fipronil.
If those compounds sound familiar, it's because it's the same stuff as in flea drops for cats. Fipronil and S-Methoprene are the compounds in Frontline Combo (that I used to use but it doesn't seem to work any more) and Imidaclopride with some Butylhydroxytoluene are the active ingredients in Advantage (which does work).
Frontline Combo is available from pet shops. Advantage is more restricted and only supposed to be available from vets. Amazon sell both because they don't give a crap.
We won't talk about the various products available from supermarkets. They're ultimately about as effective as getting your cat to roll in a patch of geraniums.
Oh, and while I understand the EU wishing to cut down on the widescale use of biocides, they have done so without having any sort of useful replacement. For example glyphosate has been banned (it being carcinogenic and definitely not dissipating in 48 hours or whatever might have also been a factor) but there are now no useful weedkillers. Nothing attacks the root system. The stuff that replaces glyphosate and carries the name Roundup (and similar) along with a similar price is either based upon vinegar (it'll call itself acetic acid) or some sort of preparation based upon geraniums.
(note, when I say vinegar I mean the stuff used in household cleaning, not the stuff you put on chips!)
Unfortunately these products, along with heat guns, are really good at destroying the visible leaves. Weeds did not get to be the menace that they are by curling up and dying at the first sign of adversity. For many weeds, using a prong to rip them out out of the ground is about the only way to get rid of them... and in some cases (brambles and bindweed), ripping the plants out and taking a rotovator to smash up anything that's left is not enough. Ask me how I know. ☺
Of course, this tends to mean things look less tidy. Out front there is moss and grass all around. Earlier in the year I cut back the grassy patch over the driveway, but now since the tarmac is old and damaged and there are grass roots, the grass is starting to come back. In the past I'd have applied a targetted pass of weedkiller, but I don't see much point as it'll just get rid of the visible leaves rather than dealing with the problem.
Likewise, you can't buy anti-mite gel or the sort of bug sprays that actually kill the things. They are being replaced by "safe" alternatives (I think one is a mixture of geranium and cayenne pepper). By "safe" in scare quotes, I mean "effectively useless".
I can't help but think that there will soon be problems as the weeds and bugs come to understand that the nasty chemicals that we used to use to keep them in check are no longer being used. Moreso as climatic change means a whole different set of nastier bugs might soon move in and set up home.
Oreo cheesecake fail
I decided to try an Oreo cheesecake, supplied in a glass ramekin in much the same style as Gü cheesecakes.
What a mess.
The taste was quite nice, but what a mess. Look at how it looks like the crumble base has just been thrown in there, it's heaped up on one side and barely present on the other side. The one still in the fridge is similar.
The place where I work, that would be a quality control failure.
And then there were two
So, then, I'm subscribed to Que Choisir for a year. At €3,90 an issue, that's a little under €50 (but may be more if they send additional special editions). And, well...
Now I have two.
Nothing to say, it's exactly the same model as the warranty version they just sent me. And, as every time, I'm going to say that I don't understand how they make money on this. Even for those who don't unsubscribe at the end of a year, the magazines are cheaper than in the newsstands. Que Choisir's cover price is €4,80 or is it €5 now?
Do you recall that I pointed out that while it is possible to swipe the screen up to enter a password or swipe a pattern, it is extremely difficult to do it correctly with a touchpad and that I could imagine there would be a number of returns due to people never being able to access their device once the password (which you're prompted to do as a part of setting up Android)?
Well, this little slip of paper was inside, and so you absolutely wouldn't miss it, it was tucked into the machine lying on top of the keyboard.
A strong hint to forget the password.
They aren't directly telling you to forget the password, but it's a strong hint to not set one.
During the initial setup, you will be invited to enter a password.
You have the option to enter one or to ignore this step.
Follow our advice:
- Don't confuse your password to your WiFi router and the access password of your portable.
- Don't enter a password on your device if you feel it is not indispensable to do so.
Click on IGNORE and then on CONTINUE ANYWAY.
Note: Every forgotten password will require the device to be sent back for correction.
Along with a diagram showing the "Ignore screen lock?" dialogue, and the pointer over the "Shut up and go away" option.
Fresh air cows?
Cows that get to wander around a field. Who'dathunkit?
A fresh air burger.
Shopping RUINED FOREVER!!!!!111!!!ONE!
Exhibit A:
Bounty biscuits.
Exhibit B:
Bounty creamy biscuit things.
Side note: They're both written in English...?
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| David Pilling, 19th May 2024, 18:45 |
Interesting to read the Wikipedia page on Roundup - it says it is glyphosphate. Bayer bought Roundup from Monsanto, despite experts saying there is little danger, Bayer is now subject to existential fines from US courts as a result of actions from home users.
I can believe that the brand name will continue but the active ingredients will change, as has happened with other chemicals.
Vinegar is like the 'if all you have is a hammer, every problem looks like a nail' saying, vinegar is all that is left for amateurs. Hence those books 1001 uses for vinegar.
A few years back Imidaclopride was the thing, made by Bayer, sold to gardeners as Provado, and of course now banned as the worst thing ever, a neonicotinide dangerous to bees.
Alan Tictmarsh used to appear on telly and say "I don't use chemicals because one day they will all be banned" - how we laughed, and how it has come to pass.
I get the feeling things are a bit more relaxed in the USA.
I saw something this week with the tag line "cut out the cow", milk substitute.
A neighbour used to ignore ants, live and let live...
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| David Pilling, 19th May 2024, 18:48 |
Lets hear it for slip rings - another type of AC motor. |
| jgh, 20th May 2024, 17:23 |
I used to avoid the products that were labelled "does not contain glyphosate". But now, none of the products have that label. So.... how do I know which one *does* have glyphosate? I can't!
It's quite calming pulling up weeds by hand, but there are always those few that you just cannot get out - only the leaves are visible, you can't get a grip on the stems, so you need to kill them in place. One particularly stubborn weed in the tarmac I carefully dribbled some creosote into it - but even creosote has been banned for over-the-counter sales!
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| Rick, 20th May 2024, 17:41 |
jgh - Look at the tiny print on the label. It has to tell you what the active ingredients are. This is usually going to be Acetic acid or Pelargonic acid. Glyphosate is usually called that, but sneaky labels might try to call it N-(phosphonomethyl) glycine.
I believe it is now banned in the EU. In the UK it can still be sold and used until 2025 (for the moment) because of the apparent difficulties in doing things "post Brexit" (like there wasn't enough advance notice).
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