Payment ring help

I’m not sure if this is the correct place to ask a question like this.

I have this EMV chip that came off of my tap to pay credit card. I am trying to put it on a ring I made, but the range is really low.

I heard that you can attach an antenna to it to increase the range but I’m not sure where to attach it. I have the original antenna it came with the credit card.

this is a coupled module… basically these are interesting in that the chip itself has its own antenna (as you can see), but how it works is that this antenna couples with a much larger antenna inside the card to get full performance. this approach is used when the module is designed to be put into cards, mini cards, key fobs, and other form factors… but without needing to manufacture entirely different chips for each product. the module is one design, one product… it gets certified as an EMV OEM product, then the final products just design a dual loop coil and this module gets situated overtop of the “small loop” and the “big loop” is what’s actually used to couple with the payment terminal.

there is no way to increase the performance of the small module antenna without doing something similar.

what card was this?

you can clearly see at least one of the pins to the silicon die as the start of the internal antenna;

the other side (outside) of the antenna ends in a via… but where does that via go to? you’d have to do some testing i think to figure it out… then you could, in theory, cut the traces to the internal antenna and attach your own… as long as it was the correct inductance for the chip being used, it should drastically improve performance.

This was a card from discover. I have the other part of the antenna, how can I attach it to the chip?

I’ll do some testing when I’m off work. Do you have a suggestion for how I should lay the other antenna out? Would I be able to wrap it around the ring?

Also i tried to use just the chip at a tap to pay terminal and got an error and it did not go thru, would adding the other antenna fix this?

You can’t really… it’s… hard to explain. Basically thing if the antenna in the card part like a 1950s paper megaphone… totally passive… the tiny mouth part is the part the module in your photo sits over… the large loud end is the part that talks to the terminal. It’s design doesn’t really allow for the megaphone to be surgically attached human centipede style directly to your vocal cords.

Hard to say without knowing the error. Payment chips must complete the transaction within a very specific amount of time, and if there is not enough power being inducted by the chip because of the small antenna, that timing might extend beyond what the terminal thinks is acceptable. More likely though, the terminal was just not programmed with discover card keys and could not read the chip… A common problem in North America.

So do you have a suggestion what I should do with the extra antenna I have or just keep it as is and try it with different card readers? I’m pretty sure that the one I tested on works with discover. I saw the discover logo, but I have not tested with the card before I took the chip out so I can’t be 100% on that.

Would it be possible to use the antenna some how so it can respond to the terminal in time?

Post a photo of the card antenna

What is the ring made of? Metal’s a no go. I also really can’t see you doing a DIY antenna in a ring form factor and getting substantively better performance than the stock tiny antenna.

Id be interested to see if that could be used as a conversion. Which country did you get it in?

It was not in this shape originally. It had a few winding in a square the size of the chip, and then the extra was around the edge of the credit card it self I believe.

I got the card in the USA. I heard about the payment rings in the UK and wanted to make one my self because it’s not available here in the USA. The ring is made from PLA plastic, I used my 3d printer to make the ring.

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That was the pickup coil for the module / chip. At this point though it’s just a bunch of wire so it’s not worth saving IMO

If it’s any help I was following this Guide

Dang, looks like I should have thought that one through more. If I was able to somehow get back in that shape do you think that would work?

Maybe I can find something online that would sell a wire like that for me, but I’d highly doubt it

Tough night be able to use that wire sure… enamel coated magnet winding wire is all the same basically… but you will need to do some research and math to figure out how many “turns” you’ll need to make and if you have enough wire.

Well dang, it might be easier for me to order another card and try to keep that wire the same way I got it.

I’ll probably play around with it a bit tonight. Should I just place the wire on top of the card and that’s all I need to do to do?

I really appreciate the help with this, I would be so lost with out you!


I might try to find a way to get the one from the UK shipped to me in the US

Im in the UK. Let me know if I can help. Is it a Mclear?
I’m still coming to terms with the fact that we have something before the US!

Why the surprise?

Alexander Graham Bell and John Logie Baird were Scots.

Tim Berners Lee is English.

It might be easier to try and convert a PureWrist bracelet in the US.