Trying to find a way to keep people from driving off with the movie speakers at our drive-in. The speakers are made of a cast metal.
Would the metal interfere with the reader?
If the metal is not an issue, what about the fact that it would have to pick up the rfid inside a moving vehicle?
I have my doubts, but it does sounds fun to play with anyway. What are my odds?
Metal and RDIF are going to be a problem. An easier and less expensive solution would be to use a metal cable that connects the speaker to a pole or something so that it can’t be taken away. At least not without taking a car door with it anyway. :lol:
Even with RFID, that’s not going to stop someone from driving off, you will just know when it happens.
Do you think people are intentionally stealing the speakers or are they simply forgetting to return them?
YellowDog:
Metal and RDIF are going to be a problem. An easier and less expensive solution would be to use a metal cable that connects the speaker to a pole or something so that it can’t be taken away. At least not without taking a car door with it anyway. :lol:Even with RFID, that’s not going to stop someone from driving off, you will just know when it happens.
Does the metal give the RFID a much harder time at finding the signal? Odds of success?
Yeah, that is a good point about the cable and the car door 
I’m trying to do away with all cables. Right now, they have a regular cable, but I planned to make them wireless so that:
people could use it with them on their picnic blanket
they could use it at our picnic tables
or
they could use it in the privacy of their own home… once they steal it…
I’m not really a fan of that last one.
If I had an RFID on the speaker and they got out with it, I could activate the land mines that I have disengaged on the exit lane.
Not really worried about the speakers surviving the explosion… Have you seen their speakers? They would likely withstand a nuclear blast…
brow:
Do you think people are intentionally stealing the speakers or are they simply forgetting to return them?
Some are. Some aren’t and bring the speakers back once it’s daylight, and they realize what they have done…
I wonder if you could do something like make them sound an annoying tone every minute or something after the film. That would make them less attractive for theft and unlikely to go unreturned.
So RFID works over radio waves, and radio is blocked or bounced off of metal so a tag inside a metal enclosure can’t ‘hear’ the RFID reader and the reader can’t ‘hear’ the tag.
Putting a tag on the outside of the enclosure can cause issues too although they do make tags specially designed to work on metal. (Railroad freight cars for example) I don’t see any tags on the sparkfun website that would work very well on a metal enclosure but a company like Atlas RFID would probably have some.
https://www.atlasrfidstore.com/
Other than nostalgia, is there any reason to use a speaker at all? It might be easier to just broadcast your audio on an unused FM radio frequency and then people could just tune their car radio to that channel. If your speakers already work on FM and you still want to use them, maybe require a deposit to check one out and the customer gets their deposit back when they return?
RFID seems overly complicated and expensive to implement and it’s still not going to stop someone from stealing, you will just know when it happens.