The second one is what I was talking about. Out of curiosity, what kind of power source will this require?
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I am using a variable power supply on 5v ATM.
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A pair of Li-ion batterys in series would be ~7.4volts. With a voltage regulator 5v is easy. How long it would last depends entirely on the amps being comsumed.
With absolutely no disrespect to leuma95 this isnāt far enough along to be worrying about that just yet.
And, Dude.
Thatās friggin awesome!
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I donāt plan to utilize a bracelet. My led is up on my forearm, so I would prefer throwing an antenna next to it under a tegaderm.
I see that in your graveyard,
you havenāt yet tried this configurationā¦
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JUST SAYING!
I hope that helps
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Those are almost tight enough! Figured I could swap put my forearm bones for iron. Boom, I can light the whole crowd up.
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I gave it a go 
I swapped the capacitor from 32pf to a 2pf one so I could try a bigger coil.
Coil works for the diagnostic card but canāt get it to light the X FD.
3 inch coil, 27 turns, 18awg wire.
And I moved the implant all over the place, nothing worked. Powers the diagnostic card from all over the place.
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bugger, there goes the neck ring idea
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How dare you give up so easy.
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Easy? My fingers strongly object to you calling it easy. There soft and delicate after all the staying inside and hand washingā¦
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@amal I feel like I have seen you talk about an HF version of the DT LF antenna for the RDV4. Would you know anyone who could point me in the right direction for a coil that couples well with the HF implants?
Edit: or simply the full specs of the coil in the xLED so I can try simulate it with some software.
I never said YOU were easyā¦ but are you?
Seriously though, looking at what you did, makes me want to learn it now.
Haha.
Itās quite fun, Iām pushing my memory though. Havenāt worked with circuits like this for more than a decade.
I usually just hook up microcontrollers to things and then do all the logic in code.
ATM I have just cloned the circuit @Satur9 had drawn up
And Iām tweaking the capacitor and coil inductance and shape, ensuring the resonant frequency stays at 13.56MHz.
But the shapes Iām using are all vaugely informed guess work.
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Well if you do actually want to get involved in this project or just hobbyist electronics Iām sure plenty of people (including myself with my hodge podge knowledge) would be more than happy to help out 
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Excellent job with the testing @NiamhAstra!
The air core coil will light the LED in the center because the magnetic flux is densest there. The ferrite core coil is closer to what weāre going to want. You can check out my last couple posts in the tragus wireless headphone thread to get some more details and links. Basically, the variables that increase field strength (B) are:
- Current flow
- Number of turns / length of coil
- Permeability of core material
So I think we can try two avenues
- Air-core bracelet with max turns in minimum length and larger amount of current.
(That transistor can handle 40V so maybe we bump that up and run a few in parallel. Will require change to circuit) - Try a different core material. Small coil (not bracelet)
I dunno, Iāll have to get back to this later
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Really, I miss configured my variable power supply and over volted them a bit and let out the magic smoke. Although maybe that was overloading the gate.
My new variable power supply is weird it (at least on this circuit) always shows 0.0 A draw which seems wrong. Was going to test something else just to see if itās like not broken and is just drawing under 0.1 A.
Iāll have a look into your suggestions some time later today 
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I also grabbed some stuff to try make a 125MHz coil just to see if I have any luck with that.