What's the difference between the contact and contactless smart cards more technically and physically is there identification to distinguish them ?

EDIT: Some smart cards like debit card will have magnetic strip also if magnetic strip is there then it can be contact/contactless i.e. can be read by any reader ?

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    \$\begingroup\$ Huh? What "cards". There are many many things in electronics that can be referred to as cards. How do you imagine we're supposed to know what you're talking about? \$\endgroup\$ – Olin Lathrop Aug 2 '11 at 11:24
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    \$\begingroup\$ @Olin "Smart Cards" (as detailed in the title) are well-known technology... I would suspect you even have a couple in you wallet. \$\endgroup\$ – Majenko Aug 2 '11 at 11:33
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    \$\begingroup\$ @Matt: First, he only mentioned smart in the title. Second, there are a lot of things that could be construed as "smart cards". Marketing people like to throw the name "smart" in front of lots of things, whether it's relevant or not. I guess by cards he means credit cards, debit cards and the like? If so, he should have made that clear. \$\endgroup\$ – Olin Lathrop Aug 2 '11 at 11:38
  • \$\begingroup\$ @Olin well, no, not specifically credit/debit. A "smart" card is any card which contains digital information. Credit/debit cards are the most common, but they are also used for identification / authentication, etc, and they aren't always 'card' shaped either. 1-wire buttons are also smart cards of a form. \$\endgroup\$ – Majenko Aug 2 '11 at 12:17
  • \$\begingroup\$ This doesn't sound like an electronics design question to me. \$\endgroup\$ – Kellenjb Aug 2 '11 at 13:09

The question almost contains its own answer! OR you need to improve the question.

Contact based cards have physical contacts, as shown by Matt.

Non contact cards use some form of electronic "signal" to transfer data. Current credit cards and similar use a technology termed RFID as Matt noted - although with smart cards this is usually used in such close proximity that it is liable to be near-field communications* using magnetic coupling rather than true RF.

Other coupling options for non contact cards could be capacitive (electric field coupling) and even optical is a possibility although not used in mass market applications so far AFAIK.

To the query "is there identification to distinguish between them", the apparently obvious answer is that because they use physically different interface mechanisms they are automatically distinguished by the very act of reading them. That is, a contact based card can only be accessed by a contact technology reader and a non contact card must use the RFID or capacitive or whatever method that the card is based on - so the system is necessarily aware of what is being interfaced with.

RFID interface coil

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Typical circuit

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EM4095 RFID front end IC overview

EM4095 Read/Write analog front end for 125kHz RFID Basestation - Datasheet

$A6.75/1 in Australia

  • Interest only - the Jodrell Bank radio telescope is used for deep space comminications. At the typical frequencies of use the near field of the antenna extends to outside the atmosphere so it is not possible to do RF testing with sample payloads without sending them into space! RFID readers do not have this problem :-).

"Contact" smart cards use physical contacts to communicate. This is like the SIM card in your phone, or the Chip & Pin on your credit card:

enter image description here

Contactless use a form of RFID to communicate the data.

  • \$\begingroup\$ Nice Pictorial representation. Thanks to this stack community every time if i have some doubt somebody in this community will always help me :) \$\endgroup\$ – Dungeon Hunter Aug 2 '11 at 12:10

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