14-07-2014, 04:52 PM
(This post was last modified: 14-07-2014, 05:07 PM by Radio Fixer.)
Well Proximity Cards are a sub set of this : http://en.wikipedia.org/wiki/Proximity_card
This is the first card I have taken apart not having ever bought an Oyster (London underground card for overseas readers). Been in Selva, Val Gardena, at the top of Italy, with the good lady. Beautiful place, more Austrian which it was before WW1 but that's off topic.
So here's the card:
As Wiki says a coil and capacitor and I reckon we can all identify those. Finding the IC has alluded me. On one card I have sliced away with the scalpel but not found it. On the other, I put it face down on Formica; its sticky, but couldn't feel a chip and these are sensitive finger nails from searching for cracks in Bakelite radio cabinets. Maybe I'm so out of touch I don't know how thin and tiny they are ?
Needs an IC to store days left on the card, time out and back (they know where you are all the time these days !). I did think that this data could be in the receive equipment but a card ID still needs to be stored.
Arthur C Clark said, roughly, an advanced civilisation will have technology that's indistinguishable from magic. To me this fits the bill and yet everyone in the walking group just took it for granted, smacked the card and passed on by.
Travel broadens the mind they say and this is a small example. I have some good antenna pics and to me what look like passive reflectors on the hillside that I will post for chat later.
Gary
This is the first card I have taken apart not having ever bought an Oyster (London underground card for overseas readers). Been in Selva, Val Gardena, at the top of Italy, with the good lady. Beautiful place, more Austrian which it was before WW1 but that's off topic.
So here's the card:
As Wiki says a coil and capacitor and I reckon we can all identify those. Finding the IC has alluded me. On one card I have sliced away with the scalpel but not found it. On the other, I put it face down on Formica; its sticky, but couldn't feel a chip and these are sensitive finger nails from searching for cracks in Bakelite radio cabinets. Maybe I'm so out of touch I don't know how thin and tiny they are ?
Needs an IC to store days left on the card, time out and back (they know where you are all the time these days !). I did think that this data could be in the receive equipment but a card ID still needs to be stored.
Arthur C Clark said, roughly, an advanced civilisation will have technology that's indistinguishable from magic. To me this fits the bill and yet everyone in the walking group just took it for granted, smacked the card and passed on by.
Travel broadens the mind they say and this is a small example. I have some good antenna pics and to me what look like passive reflectors on the hillside that I will post for chat later.
Gary
