Magnetic LEDs

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Re: Magnetic LEDs

Post by Admin on Mon Dec 24, 2012 11:25 pm

Hi Runem
I like your style. It sounds as though you have an old RR of the washing machine world. Keep it going as long as you can.

Yes, "Sequencer" is indeed the correct word to use.

As a matter of interest I have a bit of a reputation with two shops here in Sweden. The one in Rotebro is where I bought the present washing machine and when I bought it I asked if they would take of the cover so I could see the engine. Like I said, if you buy a car you get to see the engine, so why not a washing machines engine? The young lady, new to the job, had to call the manager.

I have done this same trick several times over and it usually ends up with a polite refusal, but on this occasion they had a workshop guy take of the top cover and show me the motor. I never reacted that the sequencer was an exposed PCB with a single SMD LSI chip.

If it is of any interest, today we live in a society that is getting used to appliences rusting in peace after just a couple of years. A lot of that is the "Northern Housewife" syndrom. I can give you a real example from my ex:

I bought a brand-new front-loader automatic washing machine for her about a year before the divorce. During that year I lost my job and went to Saudi Arabia. I came home to find that she had thrown a kitchen-knife at my son, but it missed and the metal handle hit the glass dome, which shattered. Did she call in the repairman? Naaaa - she spent £15 on an old, used, smelly twin-tub machine with mangle. The £15 included transport to the house. There was a bit of garden hose to replace the original that had split.

In 16 years of marriage she "disposed of" four machines and this was the fifth. At least once a year, often more, I had to carry a machine out of the house before I could open the door to let out all the water. The usual cause was a blocked filter that was never, ever cleaned out by her, so the machines always stopped when full - unable to empty.

I have a theory - Hotpoint, Xanussi, etc., all calculate the IQ required to operate the various knobs and "pushy-things" on their machines, and aim for an IQ that is about 5-points higher than the average English housewife. This is good business sence since they then always go wrong and are replaced more often.

As a matter of interest, Maj-Lis has had this washing machine for over 10 years. We had to leave the old one in the house when we sold it - Swedish tradition! Other than removing debris from the soap drawer and replacing the rubber seal round the front I have never had to repair anything until now. She has not even splashed any water on the exposed PCB Very Happy

I wonder if ICs have ferrous legs? I know they are flat and "stamped", just like LED legs. Perhaps I could try a few, including some of those from China.

BR Harry - SM0VPO

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Re: Magnetic LEDs

Post by Runem on Sun Dec 23, 2012 8:59 pm

Speaking of washing machines. I still have my old trusty ZANUSSI front loader from the mid eighties, and I wouldn't change it for any of the stuff that is sold to the typical consumer today. Almost everything on the new ones are made to just last few years and even the drums are paper thin. Over the years I have repaired the bum off my front loader. The door lock has been replaced with a metal clasp from the hardware store (from the days they actually had something like that in their shelves). It has been repainted too. But, now I'm thinking of making a new microcontroller "sequencer" (is that the correct english term?) since the old one is getting a bit flaky. I will keep this one running until it is so rusty and crusty that I'll have to sweep it off the floor.
Anyway:
Merry Christmas everyone!

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Re: Magnetic LEDs

Post by Admin on Sun Dec 23, 2012 12:25 pm

Yes Ivan,

I know EXACTLY what you mean. Only 30 years ago you could buy a washing machine with replaceable components that could be repaired. The local outdoor market sold new components. But our present washing machine is "going on the blink" so I opened up the control area.

The PCB is not even in a box!! In a water-sloshing-around-the-place washing machine! Even then there is ine large UNMARKED SMD chip in the middle, and the rotary switch has very fine plastic bits that are perhaps only just good enough for the job.

I feel that Maj-Lis will end up with a "Manual-Automatic washing machine. If I take out all the gubbins and fit a new front panel, I can put a row of toggle switches marked with:

PUMP WATER-IN WASH SPIN

At least the LEDs are not rusty (yet).



BR Harry

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Re: Magnetic LEDs

Post by Ivan on Sun Dec 23, 2012 10:12 am

Hi Harry,
I always go nearly mad when I see advertisemnts like:"You can save up to ... (CZK, EUR, USD) with our brand new ... (dishwaher, washing machine, boiler etc.)" Yes, I can save energy and water, if someone gives the device to me for free. As soon as I calculate the price to buy it, to install it and to keep it running for a reasonable number of years, the total loss is often infernal. Twisted Evil Twisted Evil Twisted Evil
And ecology ? Maybe with LEDs, the arsene will probably get out of the platic case after hundreds of years. But in the case of fluorescent lamps, the mercury vapours and strange luminophors get out usually just in the "electro recycling bin"! They are really green.

Very best regards and Christmas greeting to you and Maj-Lis
from Ivan

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Re: Magnetic LEDs

Post by Admin on Sun Dec 23, 2012 8:36 am

Just my litle twopenneth,

I thought it was common knowledge that LEDs and many other components used cheap iron wire for the terminals "stamped" out of sheet metal.

This year I have not got more than about 1200 lamps outside the house todecorate it. If you want I can supply photgraphs rusty LEDs in so-called "outdoor" Christmas light strings. Many of the LEDs have the leads totally rusted away after only 3 years use outside. It seems the little plastic thingy they are mounted in is not so waterproof.

Here in Sweden they are slowly banning all tungsten fillament lamps in favour of flourescent, ecconomy and LED lamps. The reason is that they take too much power.

I did some working out just before Christmas: if I use old fillament 2.5V lamps (80 lamps, 10W, 24V AC)) and leave them switched ON 24/7 then they last the whole season and cost SEK2 per week to run. If I switch ON/OFF using a daily timer then I can save SEK but the odd broken lamp costs SEK3 to replace. I have here lamps that are over 20 years old and still running.

A string of 10W 80-LED costs SEK200 to buy, SEK2 per week to run but costs SEK10 per week to own due to the reduced life expectancy of rusting leads.


Tungsten:
(Based on a 6-week season)
Running cost - SEK2.00 per week
Cost of ownership - SEK1.50 per week
Annual lamp recovery for spares = >90%

LED:
(Based on a 6-week season:)
Running cost - SEK2.00 per week
Cost of ownership - SEK7.50 per week
Annual lamp recover for spares = <50%

So if I am so wrong with ecconomy by favouring tungsten lamps then can someone please give me a lesson in ecconomy?

BUT perhaps LEDs may be better indoors, and I can always use magnets to mount them :-)

Seasons greetings from Harry - SM0VPO

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Re: Magnetic LEDs

Post by DragonForce on Fri Dec 21, 2012 2:17 pm

And there was me thinking you were building a time machine Razz

Seriously though, I would imagine the problem would be getting a DeLorian car that could reach 80mph rather than building a flux capacitor.....

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Re: Magnetic LEDs

Post by electrosys on Fri Dec 21, 2012 1:00 pm

Well, sounds like you guys are operating in the modern world Very Happy, whereas I'm still using my stock of components from the 1980's.

I've just pulled some of the few modern TO92 and DIL devices I have (from Maxim and Microchip) - nothing magnetic there - so presumably it's just the unbranded stuff which is 'iron-based' ?

'Fluxgate Magnetometer' ?
It's a device for measuring and transmitting information about orientation and strength of magnetic fields. I attempted to make my first one back in the early 1970's, but it never worked - not a sniff - and that's always bugged me. So - that's one of the many projects on the back burner to be sorted out 'one day' (hence the 'round-tuit' reference).

The principle is to magnetically saturate either a rod or toroid of permalloy, then reverse the direction of saturation, and measure the difference in either the time taken to saturate, or the current required to do so. The difference between the reversals is then equal to the ambient magnetic field within which the device has been placed.

Although this technique has been largely replaced by magneto-resistive and similar technologies, fluxgate magnetometry remains one of the most sensitive methods available (consistent with operating in a hostile environment) so you'll still find 'em on satellites, spacecraft, and towed behind ships looking for wrecks.

But for me, it's just a case of putting an unresolved ghost to rest ...

Colin

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Re: Magnetic LEDs

Post by Jalex2 on Fri Dec 21, 2012 12:39 am

Yep anyone that has dropped a magnet into his/her parts bin sees a real mess.
What is a fluxgate magnetomater? Sounds interesting.

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Re: Magnetic LEDs

Post by Runem on Thu Dec 20, 2012 8:09 pm

To my knowledge they have used plated steel wire for component leads, for many years now. Transistors, resistors, diodes, you name them. Even components made in the "western" world uses (or should I say USED) steel wire.

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Magnetic LEDs

Post by electrosys on Thu Dec 20, 2012 7:09 pm

Just thought I'd pass this little snippet of info along, in case it might be relevant to anyone's project ...

I was doing a little work this evening, and placed a high intensity LED on the workbench - you know, one of those you can buy in bulk on Ebay: a couple of hundred for the price of a pencil - and blow me if it didn't jump across the bench and clamp itself firmly against a magnet.

So that's how they're making 'em so cheaply - by using plated steel.

Ok, so not much of an issue with a few mA at DC - but do they still adopt the same manufacturing practices with high current devices, or RF stuff ?

One of my 'round-tuit' projects is a fluxgate magnetometer - imagine if I'd built the sensor head using junk similar to that ?

'Caveat emptor' indeed.

Colin

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Re: Magnetic LEDs

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