Using headphones/headphone jack for input to magnet implant
I have a few smart phones that are basically good but have broken screens that I've been looking for a project to work on with. I was having a hard time imagining the output from the phone to the magnet when I realized that the headphone jack is the perfect thing, assuming it can produce enough juice to be noticeable. I haven't found anything that has the range of sensitivity with these magnets, and mine is too new to test. Is that something that's out there? Would using the transducers from a set of ear buds work?
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Hooking directly to an analog sensor won't work most of the time. Practically never. There are two problems. Most sensors can't supply enough wattage to drive an electromagnet we could sense. The second problem is that the output wouldn't be a signal we could recognize. The easiest thing to feel is a pulsating field because it's constantly changing so it VIBRATES our magnets. Many analog sensors don't change frequency and the ones that do are a frequency we can't appreciate. Most of the times putting a $2 Arduino between a sensor and a coil will do the trick.
Bad news: it's not plug and play.
Good new: it's not hard to learn if you're willing.
Even better news: there is probably already a project out there similar to whatever you want to do.
This is my main question. If you amplify it, which is easy, then could you alter it analogly to be more comprehensible? Could there be a learning curb on that sort of thing?
I see where you’re coming from. Now I’m intrigued. Personally,
I rarely find a person’s pulse on the first try and usually just end up jabbing
his or her neck for a few moments. When I do find it I second guess and wonder
if I’m just feeling my own pulse. Also, street medic sounds BA. Next time lead
with that!
You probably already know there are plenty of sensors which
can detect a pulse just by touching skin. This would be great if you had to
take a pulse from someone who’s covered in blood and you don’t want to put your
hand there. That type of signal COULD be amplified. It won’t be a very good
signal mind you unless you add more components like a Schottky transistor, op-amp
or a microcontroller to activate an electromagnet digitally. The difference is
that you will feel a CLICK instead of a slow build-up which may be too subtle.
Honestly, unless someone tries this it won’t be clear if the conversion is
necessary.
Now, you don’t gain anything by using a finger magnet as
your feedback device other than only cyborgs or people holding magnets can use
the device. And the first version will look rickety so maybe not a good thing
to find in your pocket at a protest. At least it’s not a clock, eh?
Anyhoo, I have one of those amps and a pulse sensor at my
apartment so I’ll see if I can whip something up tonight. In my left hand is a
Haworth magnet and an m31. I also have “invisible headphones” so maybe I can
try those out too. Like I said, this first version will look rickety.
Can you tell me how you expect to USE the device? Do you
want to simply place some mysterious black box on your patients and know their
heartrates? Walk us through a scenario.
I mentioned the invisible headphones as an amplifier, not because I wanted to use sound. 1-2Hz would not be audible anyhow.
I haven’t done formal training with my magnet but when I pass my hand over something where I expect a field and I don’t feel one I realize it. Like seeing a room where one of several lightbulbs has burned out. For your training you could simulate a particular heart rate, 80bpm, and get used to the rate. From there you could estimate the difference and say, “This heart rate is (significantly) faster/slower than 80bpm.” But you won’t be able to tap a person on the shoulder and know their heart rate in a moment.
Most likely the inexpensive heart rate sensors from eBay will be prone to noise and only fluctuate a tiny bit. A microcontroller can detect these changes but if I’m right an implanted magnet would not move noticeably.