coil sensing

[george]

I'm a little bit of a newb at this so bear with my simpleness. I'm wanting to make a coil system similar to those used for shoplifting alarms. I'm just wanting to detect when a 'device' is inside the loop of a single sensor coil. I was thinking about using a PIC to do any figuring out of stuff that needs figuring out, but not sure how to exactly go about it - preferably it wouldn't be triggered when in the presence of metal objects - just the slave coil. - What's the best - easiest/reliable method of doing this? Do I pulse a frequency and look for a return? Do I look for a frequency shift when a similar tuned coil moves into range? Any suggestions would be greatly appreciated.

[TheWizard]

You need info about RFID....

Texas Instruments - HF Antenna Cookbook 11-08-26-001 Jan 2004 Radio Frequency Identification Systems
http://www.ti.com/rfid/shtml/rfid.sh...+home_p_tirfid
Microchip - AN710 Antenna Circuit Design for RFID Applications
http://www.microchip.com/stellent/id...UserText=an710

...

http://www.media.mit.edu/physics/pub...9.fletcher.pdf

[Nihil Roma Maius]

Coil sensing schematic and website (LOOK ALL THE LINK) and GREAT INFO!!! in pdf:

http://www.abelsim.co.uk/doc/help/tbellex2.htm

http://1.1.1.1/311080236/248733792T0...9.fletcher.pdf

[george]

Hey, that's perfect info - just what I was after thanks - tho I can't seem to find the CS209A anywhere does anyone know of any suitable replacements?

Cheers

[george]

I've found a TCA355 manufactured by Siemens which might do the trick, how do I figure out the frequency that the coil/capacitor resonator will resonate at? Thanks

[Sean_Goddard]

CS209 Used to be made by Cherry Semi (Yes the same people who made the keyboards) but now it's an OnSemi (Motorola) device.

This device is still used in countless probes like the Sherlock, and many others. Not very sensitive though.

[Max]

CS209 Used to be made by Cherry Semi (Yes the same people who made the keyboards) but now it's an OnSemi (Motorola) device.

This device is still used in countless probes like the Sherlock, and many others. Not very sensitive though.

Hi,
OnSemi is a Motorola company, but the strange is that there are same products by OnSemi and by Motorola (stamped) that differs one from another! Looking at datasheet of 2N2222 of both I've found interesting differences (e.g. if you think of using them in rf applications) but why ?

I think that old branded motorola parts (that I find sometimes also in stores too, maybe old stock parts) follow old specs. and then newer follow new specs. due to better manifacture process variations (and maybe new agreements between manifacturers ?).

Anyway, it's just another components mistery!

Best regards,
Max

[Nihil Roma Maius]

You can buy the CS209A in the net via credit card.

Here the same style.
http://www.ringing.info/abel/notes.html

[chemelec]

You can buy the CS209A in the net via credit card.

Here the same style.
http://www.ringing.info/abel/notes.html

The CS209 was Discontinued years ago
But I Also have the CS209.

But be aware that its maximum detection distance is LESS than one Inch.

There is a Simular, Newer device, part number "TDA0161".
I have it also, but its also a Poor detection distance, like the CS209.

Gary

[Max]

The CS209 was Discontinued years ago
But I Also have the CS209.

But be aware that its maximum detection distance is LESS than one Inch.

There is a Simular, Newer device, part number "TDA0161".
I have it also, but its also a Poor detection distance, like the CS209.

Gary

Hi Gary,
yes, if I remember well they were intented as proximity detector for e.g. older RFID-badges detection some years ago. You have to creep the rfid/mixed badge on the top surface of detector column... then followed RFID handshakes.

Not like actual RFID tags, where no proximity detector is needed.

I remember that the damn thing many times missed the detection of the smart badge... have to try 3 or also 4 four attempt sometimes. Due to the few range detection of metals on the badge surface.

Kind regards,
Max