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What type of security tag is this? Answered

Could anyone tell me what type of security tag this is?
I have Googled and Wickipediad en.wikipedia.org/wiki/Security_tag 
around the subject looking for,  'induction coil security tag',  but I mainly find information about the flat strip type.

I'm new to electrickery so I am guessing it is an induction type of device?
Also, is the green component a capacitor?

Thank you.

5 Replies

steveastroukBest Answer (author)2010-02-24

Its not an ACTIVE tag, its a PASSIVE tag. Its designed to cause a detector to get upset when the tag is near it.

The detector is a tuned circuit, oscillating at a fairly high frequency. When the tag nears the detector, it increases the losses in the detector and triggers an alarm.

Really simple.


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guymark (author)2010-10-04

Hi, an old question now but just in case you are still wondering....

This certainly appears to be a tag - but an incredibly heavy duty one and also one which appears to have been made to operate at a very low frequency (hence many turns of wire over what looks like a ferrite rod).

Usually re-usable tags consist of about 7 turns of copper wire roughly 40mm in diameter and with a 100pf capacitor going from one end of the coil to the other.

Make that up and walk through most shops gates and they will go beep at you :)

The ones above are normally running at a few Mhz - IIRC - but your device looks FAR more likely that it has been designed to operate in the KHZ range.

I would guess it makes it much more capable of operating over a longer range (outdoor sales area at a fair??). Certainly it is an expensive component (compared the the usual couple of foot of wire and a 1p capacitor.

The green thing is indeed a capacitor - and not only that the value is 1n2

(101 = 100pf 102 = 1n 103 = 10n 121 = 120pf 122 = 1n2 123 - 12n)

Kind Regards


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RavingMadStudios (author)2010-02-24

Are you sure it's a security tag? Did you remove it from a plastic housing or something that was attached to store merchandise? Possibly a description of what you found it in would be helpful in identifying it. As is, to me it looks more like part of an electric motor or a guitar pickup than a security tag.

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Thank you both from RavingMadStudios for replying.

I seem to recall opening up a light grey security tag ,( that had been left on something from a shop), and all that was inside was this ... my recollection is not always the best but it seems like a clear memory... it is possible  that I'm wrong, in which case I apologize for wasting your time.  

Best Wishes

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NachoMahma (author)2010-02-24

.  My guess is that it's an inductor or part of a solenoid. Also guessing that the green thing is a capacitor to absorb spikes when you turn the coil off.
.  I'm with RavingMadStudios - need more info and it sure doesn't look like a security tag.

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