Electrical Waste, signs of change perhaps?

[TonyDuell]

Originally Posted by electronicskip

The best keyboard I've ever had was on the Texas TI99/4a computer.
Solid action, heavy duty.

The same keyswitch (leaf contacts that normally spring together but are held apart by the plunger when the key is 'up') is also used in early versions of the TRS-80 Model 1, HP85 series machines, DEC VT52 and VT100 (and related terminals), etc.

I've used contacts from a dead VT52 keyboard to repair some of the other machines.

[TonyDuell]

Originally Posted by G6Tanuki

The old IBM 3270 display-terminal keyboards used a 'buckling spring' mechanism to give the snap-action. They were _incredibly_ noisy compared with modern keyboards - something like the payment-processing department of a large utility (with 100 or so operators sitting in front of screens keying-in transactions was rattle.rattle.rattle all day long. The first IBM-PC keyboards were no quieter.

They rarely failed mechanically: usual cause-of-death was tea/coffee/coke being spilled, which mixed with the inevitable accretions of skin flakes, hair, bits of biscuits and cigarette ash to cause tracking on the under-keyboard PCB.

There were 2 distinct designs of IBM 'clicky' keyboards. The original ones (used on the PC, PC/XT and probably on the mainframe terminals, etc) were capacitive. Pressing the key moved a plastic flap, changing the capacitance between traces on the PCB.

The later one on the PC/AT was actually a membrane switch keyboard. The 2 layers of membrane were pressed together by the plastic flap that was part of the buckling spring mechanism. This type is a lot less reliable than the capacitive one.

One of the nicest key'switches' I ever saw was magnetic. Insider were 2 wire loops coupled by a ferrite bead. There was a magnet on the keystem that was normally next to the bead. The magnet was strong enough to saturate said bead. You sent a current pulse through one of the loops and looked for an induced voltage in the other one. With the key 'up', the magnet saturated the bead so the current pulse couldn't increase the magnetic flux in the bead. So no output in the sense loop. Press the key, the magnet was moved away, the 2 loop were now effectively magnetically coupled by the non-saturated bead. Used on the HP9845 (and other machines...)

Then there's the keyboard using transformers made of spiral PCB tracks used on the HP9810 and HP9820 machines. Oh and the electromagnetically encoded ones used on the Termiprinters. But those can wait for another day/thread!

[kalee20]

See the attached page from Electronics Weekly, August 15th.

I tried to find an online link without success. I then looked for any copyright claim in the printed issue - couldn't find one! So I feel hopeful that posting the photo won't cause any trouble.

[music-centre]

They are discussing on Radio 2 at present a proposed change in the law by Michael Gove to allow people to go through council tips and remove items to re-use - hope it goes through!
Steve.

[John10b]

Yes I agree, but I did read one member was against this on H&S grounds, I’ll be interested to follow this debate.
Cheers
John

[chriswood1900]

Well done Michael Gove if it goes through, I never cease to be amazed at the amount of perfectly good stuff thrown out or just needing minor repair at our local dump but you're not allowed to have it on some spurious H&S grounds.
There was also some interesting reading on the culture in Finland where they have much less of a throwaway culture.
see here https://www.bbc.co.uk/news/science-environment-46099418
Chris

[Guineafowl]

Originally Posted by John10b

Yes I agree, but I did read one member was against this on H&S grounds, I’ll be interested to follow this debate.

When anyone cites H&S grounds, I always want to hear exactly what grounds. H&S is so often (mis-)used to prevent perfectly sensible adults from going about their business, ignoring its real origin as a 1974 framework for worker safety, and nothing to do with stopping kids from playing conkers. Idiocy stops conker games, not the HaSAW act.

“What about the cowboys?” you cry. Almost by definition, cowboys ignore the rules. So an H&S crackdown will only crack down on the majority (important word) of responsible people, who either have the nous to repair stuff, or have the nous to know they can’t.

We can’t womble at the tip. But we’ve been able to womble on ebay (spares/repair) for many years. How many shocks and fires can we directly attribute to a wombled appliance in these days of RCDs and double-insulated devices? At the same time, how many thousands of appliances have been condemned to landfill for one cracked solder joint, or a loose ribbon cable?

Instead of a ‘stick’ approach, why not a carrot? Yes, you can scavenge at the tip, but produce a PAT tester cert., or cut the appliance cord off so the thing requires some level of knowledge to repair, and can’t just be flipped on again in an unknown state?

[richard.cs]

Interestingly most microwaves I have disassembled do seem to be designed with repair in mind. For example on the turntable motor is on the underside and inaccessible without a lot of disassembly, but there's usually a pop-out section on the base. It's just part of the pressing and not used in production but you can snap the sheet metal, change the motor through the resulting hole, and then it's designed so you turn it around, slide the tabs in and secure it with a single screw. I'd say more than half the microwaves I've seen have that feature.

[Refugee]

I wonder how many microwaves are floating around with only one screw on the motor?