Reed relays for trick capacitive buttons?

With the titan coming this idea just popped into my head. make something that looks like its just capacitive touch buttons or otherwise touch-sensitive but in reality just has reed switches (those are the ones that turn on with the presence of a magnet right?) behind it. then use it with the titan implanted finger to trigger them and then watch as others try and fail to use it with normal fingers.

Viable? interesting concept?
i don’t know but i thought of it and wanted to write it down before forgetting


Sounds doable, but I guess you’d want a titan in your index finger then.

I like Roscos approach with his doNExT, read ID + find triangular light pattern.
I want to play around with a similar idea, but with magnets.
Like a reed switch + read ID. Or maybe something that measures the magnets strength, so it has to be a titan to work.

If I had an implanted magnet (and believe me, I would like one, but I just can’t get over the unwanted side effects), I’d setup some kind of small glass container with ferrofuild in it, with a backlight and a camera to detect the signature pattern of that particular magnet. At least I’d have tons of fun experimenting with that. But… that ain’t happening for me.


There are small solid state (no moving parts) sensors for that exact application. Well, not for fingers, but for magnets. Try looking up hall effect sensors.

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I have a leftover burning laser diode from my engraver that I wired up with a Reed switch to use as a pocket lighter that only I can use. It worked pretty well.


Some cool ideas here, I’ll have to mess around once I have some free time

I was considering having a xg3 near a flex so I can use it as a power saving feature for car unlock stuff.

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tell me more about these unwanted side effects…

Well, mainly the inability to get pass an MRI scan. That’s totally unacceptable to me.

In close second, the inability to work in a workshop with iron fillings and iron powder all over the place. I work metal at least twice a week, and I do NOT want my finger attracting that stuff to my skin, or magnetizing my tools or my workpiece. Totally unacceptable also.

And then there’s the danger when manipulating magnetic-sensitive things. Believe it or not, where I work, we still back stuff up on DAT tapes. I have to change the tapes 3 times a week. I also regularly have to dig out old files on diskettes and bernoullis. I would be a real liability for my company. Not to mention wiping hard drives, messing up CRTs (getting rare those though) and whatever else I haven’t thought about yet.

Too many downsides for me, sadly.

Of course, if the Titan had an on/off switch, I might reconsider. Stretch goal Amal? :slight_smile:

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I hear ya. I’ve thought about how it could interfere with electronics projects. I won’t get one in the finger for that reason.

The magnetic field from a titan or similar implant is too small to affect anything solid state. You would need a really big magnet and you would have to move it around quite a lot to make any sort of change.

Hard drives on the other hand… the probability of flipping a bit with an implant is extremely small. I wouldn’t risk it with other magnetic storage mediums though :slight_smile:

Hall effect sensors should be plenty sensitive… but, I mean that’s their job :wink:

If it helps, it’s the same type of sensor used in automotive applications to count the teeth going by on a metal cogged / toothed wheel. Usually either Crankshaft, Camshaft, or Distributor shaft sensor.

Of course hall effect sensors would be the exception along with magnetometers which are often used in 9 axis IMUs.

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Interesting, I’ve been toying with the idea of using a xg3 to activate a relay, that would power a XAC in my side mirror of my car,

The power draw is a concern for me, maybe I shouldn’t be concerned, but some form of power switch would make me feel better

New here. What specific side effects are you avoiding?

Haha found your response already thanks

The power draw is what keeps me from outfitting my car. I start it every once in a blue moon, so I don’t need something that’ll drain the battery even faster. I already have to top up the battery half of the times I want to use it.

I’m still wondering if a capacitive proximity sensor or PIR motion sensor could be employed… or even an IR proximity sensor… anything low power that can easily detect the hand coming in to present a tag, and turn on the reader for that.

There are ways to save battery without doing any of that. It’s just that I can’t be assed to roll my own.

Case in point: the BeCode AIR+ camlock on my locker at work: that thing achieves fantastic battery life with a single (admittedly large) button battery.

I actually got curious to know how it achieves this, and it’s really quite clever: apparently it seems to detect the patterns of times when I use it, and sends probe pulses more often around those times, and a lot fewer outside of them. I know that because I arrived at work really late once, and I had to wait quite some time for it to open - long enough to wonder if it was broken. That’s what prompted me to study it.

Also, it seems to detect when the locker room is lit and goes to deep sleep if it isn’t.