I would go for a flat 2-3cm wide circle. You are going to have to know the properties of your wire to determine the number of turns based on the diameter and then try maych that with an appropriate capacitor.
Okay so using this and an inductance calculator, since I have 22pf capacitors, and 0.0034" diameter wire, I’m gonna be looking at around 283.7cm of wire or close to ten feet, if I get a larger diameter wire I could do a smaller length but I don’t have that on hand so we’ll see how clunky it actually gets 
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Yes, that sound about right. As long as it fits in a phone case 
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I figured it out. The flux must flow!
Ordered the final revision. Even if it’s a tiny bit off I’m going with it. Can’t endlessly stress over perfection or you’ll never get anything done. I’ll report back once Amal encapsulates mine and I’m ready to get it installed. Then I will probably open up these as an option for conversion.
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Worked out okay. Gonna go test it with a couple transactions on verifone readers. I’ll post video. Then I’ll be sending it to Amal for encapsulation so I can implant.
Apex for comparison
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Got it working very well on most readers.
Unfortunately @Eriequiet couldn’t get it working on the big Verifone readers. Haven’t tried the smaller MX915 but after I implant I’ll let you know if it works on those. It’s better than the Purewrist conversion but only 20-40% better because I didn’t nail the tuning (unfortunately this is self funded so that’s the best it’s going to get for now)
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Speaking of the veriphone,
Came across a new reader at one of the gas stations near my work that get to act as a bit of a test location for terminals and pumps for they chain
This new thing looks to have a nice compact and potent field near the top…
You’re frequency master, all I can do is stick a xFD on it, but looks promising 
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The problem we’ve seen with these terminals, specifically from verifone, is that they tend to overpower the field. It’s like every aspect of their design was meant to communicate with active devices like phones for payment. This means they work great for Apple pay and Google wallet, even if the terminal is shrouded by a metal mount, or wedged between some other point of sale equipment and effectively does not have very good “clear air” around the antenna. The downside of course is that these terminals are pretty shit at actually communicating with passive transponders. They might power the transponder at pretty good distances, but the quality of the connection is so bad that data cannot flow across the shared magnetic field. At least, this has been my experience.
This one seems better, there is a very strong and concentrated sweet spot on the top left, the teller Has been advising customers to put their credit cards there for a better read, teller says it seems to perform better than the previous bastard
I only had a minute or 2 to poke at it, lest the teller loose amusement with implant shenanigans
But it seems like the antenna is smaller, starts in top left and only travels half to 3/4 the length and depth… screen feels much thinner and body feels like there’s more plastic and less metal Inside it, along with no metal clamp
I was stupid and forgot there’s a chance it could have picked it a x series… should have tried
I’ll dig out my show and tell rfid bag, and take that failed encapsulated flexnt2 you let me have back and see how it responds next week
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Still waiting on the encapsulation from Amal, but here’s some data on another CoM module I tested. Unfortunately it was much bigger and had a slightly lower peak, but neither of those are deal breakers. Maybe if I get mine back and it works okay I can see how many people are interested and make one more pass at the design to account for these inconsistencies.
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Is funding still an issue for this project?
Hey Jirvin
Yup, you want to help out?
Hey Satur9,
Happy to help out.
What stage are you at with this project and how much additional funding would be need to complete/advance it?
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Depending on the project goals. One more revision should cost ~180-250USD and that would let me fix the tuning of the existing board. To properly accommodate larger modules like the one I pictured I might want to make the antenna larger, and if I did that it would need two revisions, one for characterization and one for tuning. So either 250 or 500USD depending on people’s interest in the larger modules.
Somebody reached out because of your message and offered to donate a bit. I’m definitely not interested in any kind of “pre-order” and I’m leery about donations, but at this point I really don’t have a choice because I’ve already put so much money in.
It would really help if people who are interested in this type of conversion could post pictures of the contact interface of their suspected CoM cards with rough dimensions of the module itself (no need to melt the card down, and don’t post card numbers)
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I think what you are doing is noble and I understand the “not a pre order” etc.
People should be aware that is simply a donation to " help a brother out"
- Do you have some preferred payment methods that you can prodide?
A variety of options would be good
Bank Transfer, Paypal:
(or equivalent), crypto
(or equivalent), cryptoAlso, Even people that dont want a CoM conversion, they may still want to donate…
By the way, Did you want to start a new thread for just CoM?
, This one is intertwined with Repeater stickers(I know they are related) and it would take a while to seperate them all out.
But if you left this one for the stickers/repeaters and a a new specific CoM thread, you could link back to relevant posts in this thread…Just a thought
OTY
Nah. This is still an active development thread. I think I’ll start a new one that’s all neatly organized an informative once we have things worked out.
I don’t need very much money for this, and I’m concerned if I publicly post payment details people will go overboard just because they appreciate what I do. If people DM me and we negotiate exactly how much you want to donate beforehand that could work.
Anybody can contribute by stating their interest. I’ll leave a poll here, even if it’s going to be lost in the thread. Anybody who is interested please try and post info about banks that have CoM and possibly pictures of the contact interface of cards with dimensions of the module so I can get a more accurate representation of what’s out there.
Are you personally interested in a CoM payment conversion
- Yes
0 voters
Makes sense
I get what your saying and doing, and if thats how you prefer to manage it, thats your decision.
If you got more than expected, you could put the excess into “the next project”
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I think I screwed up the poll so it doesn’t show who voted. I am not good with computer.
EDIT
Alright, fixed it
Right right I’ll make sure to put a “No” option for those naysayers out there who just want to rain on our parade