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electronic/mechanical/ LED-Radio-Decoder Wedding rings? Answered

Hey there,

my future wife and I are looking for some fancy wedding rings. Well, we're both geeks, so it should be something that involves electricity or a nifty function ;-)
Unfortunaly she's allergic to some metal components often used in steel or gold/silver, so titan or something like that would be more suitable. Aluminum or some plastics would work too, i guess.

Thats the problem right there. Even if we'd find something online or a store that makes rings, they'll probably not work with titan since its harder to work with.

I found some LED rings at

but as allways the problem is the metal and of course power.
A battery would either have to be replacable or rechargable ;D (capacitor? but even a low current led wont even flash up with a tiny capacitor?)
A solarcell so tiny it'll fit ontop of a ring without looking redicoulus would not be efficient enough I'dd guess.
Of course, as previously stated, it could be something mechanical (as http://www.switzerwatch.com/product_info.php?language=en&viID[4]=30&products_id=1297 for example)

A nifty idea would be if the rings would actually do something when brought together (magnetism, induction, mechanism).

I also had the idea of the rings morsing the date every few minutes on radio, much like http://www.mcmanis.com/chuck/robotics/projects/eelb.html

if all fails we'll just look into something cool to engrave (there are rings with laser engraved fingerprints as example) or we'll just embed a electronic part such as a resitor with a value representing the day we've met or such.

ANY (cool) ideas apreceated, especialy about LEDs, sources/shops, adresses to shops customizing, and so on (but please, nothing over 50-200 bucks, we're not rich).

I hope you guys / gals dont start to laugh at us now. We cant help it. We just want something unique and not a golden ring with some diamond. Some people really have rings that look ugly! Well, geeky LEDs do too, but at least they do something ;-)



10 years ago

Can't help you with the power problem, but it strikes me that a little red "heartbeat" LED would look really cool. You could have an oscillator which is weakly coupled to your own heartrate (maybe electrodes on either end of the ring?), but more strongly coupled (photocell? inductively?) with the second ring. You could use it as a rough heart monitor when you're out jogging by yourself. But when you're holding hands with your sweety, the two rings would beat in synchrony!

Neat idea :) Or I could use IR for the "Ring-Link"; Unfortunaly the SMD TSOP and such are pretty bulky... I wish I had more space, not only because I never soldered these tiny parts before but also to include more power which seems to limit creativity the most :-(

Thanks for the link! Yes, I had that idea too, but such a batteryholder is just too bulky for 24/7 wearing ;.) Unfortunaly the project is on hold for now as I would have to order in 4 different shops, spending 4xpostage, plus I have other things to do at the moment.

Did you make it yet? If not, try making the whole thing an induction coil. A few SMD diodes makes a rectifier, and you may be able to make an "old-fashioned" capacitor using 2 loops of metal. It would be a simple LED blinker, turning on whenever it has power, but its worth a shot, and it'd be cool. :P

to make it even smaller you could use a smd bridge rectifier....but personally I can't even see them well enough to use them LOL

Haha! I always just stick with diodes, because its less types of parts, are they really small?

Ok, I had the physical catalog in my hand and thought I would mention it. I didn't look at it closely though.

Yeah, induction was one of my thoughts too, especially for the interacting part. Still, its not a good power source Im affraid :-/ The radiowave emitter will probably be the only thing that will run from the tiny solar cells, as the capacitors in that smd size will not store enough for a led to do something constantly :-/ I hope I can make these things soon.

Here's a crowded sketch of the components that fit into the ring. The ring has a inner diameter of aprox. 21mm and about 25-27mm outer diameter (about an inch). I have ordered components for a programmer and some pics to test, if and how I can reduce the voltage and current needs of this circuit. Also I must test if a small capacitor is required to mentain a stable supply, but due to the small size, it will only work with small capacitors and therefore as long as the sun shines ;-) For casting the ring, it will be a bit simpler then on the instructable mentioned here. I will use a cheap plastic / silver / metal ring to create a (probably silicone) form I can re-use. I will then fill it with epoxy (or another cold drying plastic-like substance) just a fragment of a millimeter so the components will not stand out on the sides. Then I place the electronics inside (I am still wondering if I can solder such tiny SMD components, oh my) and fill the rest of the form. That should do it, since there is no batterycompartment or such it will be the easiest part of all. Now I only need to test if the minimalistic power supply will be able to do the trick. The solar cells are specified with 14mah short, 10mah. Broken/cut in half thats 5mah or in real use maybee 3-4 in bright light. The unmodified cicuit needs about 3-4mah, so this should be able to work if I can exchange some components to reduce the current and insert a capacitor to prevent peaks that will pull to much from the cells. Then again, I would need an extra cell for a diode (voltage drop) so the capacitor cant discharge over the cells...


Hello again, here is a quick sketch of the ring and the component in size comparison.
The ring I am currently wearing is about 2mm thick, 5mm broad and 22mm in diameter.
A inch equals 25.4mm.

I am not too experienced with electronics and unfortunaly I have not set up the circuit of
http://www.mcmanis.com/chuck/robotics/projects/eelb.html ,
but unless the transmit-power usage and especially the required voltage requirements can not be reduced, the batteries are a big problem.

The used cells in the graphic only have 5mA (and 1.5v each).
Lets asume the pic will idle with a rewritten program with 100 nAh as in the datasheet, so that is nearly nothing.
Then it will transmit a short sequence for 3 seconds every minute.
1200 messages equals a 1 hour continous transmission, which would draw arround 3-4mAh.
The total runtime would be 1200 messages = 1200 minutes = 20 hours.
Depending on the real battery capacity and the exact power requirements the ring would work a day or maybee two, which is not too great :-(

Lithium cells have 3v, but unfortunaly, have a much larger diameter.
The pic requires 2-5.5v, but I dont know how this will affect the transmittion. Since the voltage would change I suppose the volume of the beeps and the range would decrease?

Also I only found few rechargable buttoncells- all far to large to use.
Same as with capacitors (goldcaps for example).

As for the flexible solar cells I found, it seems like they have contacts at the end, meaning that I can not cut them like regular solarcells which you can break and use a random contact at the back and a contact at the front.

Another alternative would be to use a stepup circuit, as used for powering LEDs on a single cell.
The advantages would be that I could use a larger buttoncell (due to the fact that the three tiny ones use up most of the space with their case, the capacity of a single large one would be much better) but I would have to include more electronic and wind tiny, tiny coils. I dont think I can do that.

The powerissue is really the biggest problem, help.

I seem to have troubles attaching pictures using Opera 9.02.
Link to picture

You can get LEDs about a 1/4 inch square. A pair of those on the shoulders of the ring, a small surface-mount LED as the main setting, and a small capacitor...

This is getting too big for a "normal" ring. Maybe you're going to have to go the way of an Indian wedding ring - plenty of space there.

>lightbulb< Each ring is a hollow tube, with a copper coil within. Parallel to this is a strong magnet. When you hold hands, each person's ring will induce a current in the other, charging a small capacitor. When it's full, the capacitor dumps it's charge through your skin, giving you that tingle you felt back when you first met.

giving you that tingle you felt back when you first met.

Even if on only one finger LOL

Sounds like another "Store security system exciter" :-)

Even if on only one finger

I could make a rude joke about where the one finger was, but I won't.

I didn't know that is the finger where the British wore their wedding rings ;-) I learn something new every day. LOL

On a different note: If you could get a hold of some of the nanotechnology being developed at MIT, one could have the plastic rings, as they touched, create faux gold (yeah, this is still only theory, I know) gotta love quantum physics though....

Even with technology available at a good electronic store so many things would be possibe, maybee not faux gold, but color play, displays and such, but power supply remains to be one of the major issues :-(

Hehe. I looked arround for micro power generation, piston engine, tiny peltier elements, body heat generating electricity, but mostly just found prototypes or too-large devices. Seems like this is not an option yet, since its just proof-of-concept to generate elecrticity of bodyheat, at least at such a small scale.

Neat rings :-) Well, 1/4" = 6.35mm so there even smaller LEDs (3mm or SMD) but the problem is the capacitor. I checked a few projects and a 1F capacitor will run a bright 20-30mah LED 2-3 minutes, but small capacitors will have a fragment of the capacity of a larger 1F capacitor, thats why batteries seem the way to go :-( A 100uF cap will last only seconds, if at all.

The magnet idea is neat, though today we talked a lot about possibilities and decided magnets wont be credit card friendly :-( The only possible interaction could be IR, though a TSOP IR IC is rather bulky. Still, the range would be several meters. At least the microcontroller tranmitter idea can be done with tiny SMD components.
Speaking of, a tone decoder IC might be another solution for a interaction? Anyone here ever used one?

This project turns out harder then i thought :)

Even smaller ICs could have some sort of a temprature sensor, but im not sure at the moment if the SMD sized ones have a/d input.

Well, still a few months to go, so there might be other ideas. Its a real neat project idea, though miniturizing circuits and power supplies is anoying .-(
Again, if anyone has a link to smaller bendable solarcells, let me know :) It could go arround the ring, and 2-5 mah is not too unrealistic, at least in bright light...

You can cut glass solar cells - can you not cut larger ones? Or maybe contact the manufacturer direct with your plans - they may do you a discount / freebie if you let them use the idea in advertising.

Kiteman, yeah, solarcells can be broken down, but I am not sure if those flexible ones can be cut to any size? I have not found any info on that yet, and they arent really inexpensive either. Thanks for the link iman :-) I'll read up on micro thermopiles, I wonder how much power they can generate.

I wonder if you could rig a "mood ring" so it was #1: either closer to the hand so it got more warmth, or #2: could be warmed another way ? That would be different but not overly nerdy

. There is at least one iBle on making cast plastic rings - maybe it could be adapted for your purposes. I think physical size of the components and the power required keeps this out of the DIY category, but who knows. . How about embedding a RFID tag in your rings? Small and no power required. Then you could build a project that would recognize when both rings are present and do something sweet/romantic (eg, play "our song").

I found https://www.instructables.com/id/How-to-make-a-Green-Lantern-ring--including-a-glow/ which seems a pretty neat idea if we'll make the rings ourselves ;-) At least the battery compartment is a neat idea that would save some hastle. Still, I would love to check if its possible to use a tiny bendable solar panel. I have found a few (german) shops, but would be happy for any links arround the globe. The solar panel should be able to provide 4-5mah and arround 4.5v, at least in relativly bright light)
I guess it could go into the epoxy/plastic casing :)

Solar cells such as http://www.lemo-solar.de/12103b.jpg can end pretty much, and this one is not too big either- but its 1,5v, 400mah.
Something like 5v 10mah should do the job and still provide enough power in good lighting conditions.

Well plastic or such would just be the last option I guess, it should look a bit like a wedding ring ;) But plastic and aluminum could be done with the cnc of a friend I guess... I did think about RFID, but as far as I know it only stores ongoing numbers, though I guess it could be manipulated to a number of our choice, but not as small of size probably. Well, SMD is a pain in the rear and luckily I never needed to soldier something smaller then regular electronic kit parts, but it allows tiny DIY projects, and if its just a few components soldering should be do-able?

Skip the rings and go for an RFID implanted in the back of your neck. Now that your getting married she will probably want to keep track of you;-) BEEP...BEEP...BEEP... Cheers, Pat. Pending

Hehe, yes, indeed, many store's theft-systems would go off ;D

You are talking a REALLY small package there for the electronics (unless you want, either a somewhat big ring case, or a wire coming off of it...)

What I meant was, if you were thinking diy, it would be rather bulky, unless you are really skilled at handing and soldering those micromini surface mount components (I personally can't even see them anymore LOL).

I cant either, but I could ask friends to do it ;-) As i said its just an idea, it does not need to be electronic or custom made if we find something else, but the idea of a microcontroller or led (or something up that aisle) would be neat. I guess getting a electronic part into a ring without a function could be done by most shops who custom build jewlery, still, something more geeky would rock my socks.

Well SMD components are rather tiny,
so for the radio idea using the microcontroller see
http://www.digitalspirit.org/wiki/docs/pic10 for size comparison. I think its available in 3x1.6x1.1mm according to a other site.
Since it would just need to beep once in a while or even just once when tapping a contact, my guess would be a small capacitor would do the job.

Anyway, it mus not be that fancy, though the more unusual it is the better ;-)