Norman Potting
Well-known member
Our local Tesco has a sign saying "trolleys will stop if taken beyond this point".
I tried it with one once, and it did. How?
I tried it with one once, and it did. How?
Found this which seems to solve the mystery
As a Tesco trolley collector (just part-time while at uni I hasten to add)
I preferred it when I didn't know the answer and could marvel that it just happened due to some unknown factor.
The real reason relegates this particular wonder to the 'boredom' pile.
Found this which seems to solve the mystery
As a Tesco trolley collector (just part-time while at uni I hasten to add) I can confirm that these merely refer to the wheel locks on the trolleys. They operate when they pass over the buried magnetic surface at the car park boundary. This drops what is basically a small rubber chock in front of the wheel, stopping it almost immediately. They do not need to be sent away to be unlocked, all of us carry "keys" which reset the mechanism[/Q
This is how- clever stuff.
I preferred it when I didn't know the answer and could marvel that it just happened due to some unknown factor.
The real reason relegates this particular wonder to the 'boredom' pile.
No it doesn't. The next time I go to Tesco's I shall take a magnet with me. Hours of endless fun magnetising trolley wheels and causing mayhem when people can't push their trolleys around cos I have fixed their wheels.
I still wonder at how the 'touch-screen' on devices such as iPhones works.
I'm sure somebody tried to explain it to me once but it went over my head.
There are three basic systems that are used -
Resistive
The resistive system consists of a normal glass panel that is covered with a conductive and a resistive metallic layer. These two layers are held apart by spacers, and a scratch-resistant layer is placed on top of the whole setup. An electrical current runs through the two layers while the monitor is operational. When a user touches the screen, the two layers make contact in that exact spot. The change in the electrical field is noted and the coordinates of the point of contact are calculated by the computer. Once the coordinates are known, a special driver translates the touch into something that the operating system can understand, much as a computer mouse driver translates a mouse's movements into a click or a drag.
Had 'em for ages but I still find it pretty mind-boggling how planes stay in the air.