1st wire: 1 end in GND, 1 end in Pin 13, coiled in the middle
2nd wire: 1 end in cathode, 1 end in anode, coiled in the middle
What do I need to make this work? Adding any components or will this work in itself? I made it so simple because i don't know if I need all the components in the page as he was connecting it to a toothbrush inductive charger where mine already has proper current for the LED.
So if I coil it up good (it depends on the number of turns of the wire so I've read) and make the two wires "almost" touch this will work in its current state? Or would I need to change anything. About the diode, where would that go? Cathode? or Anode?
It will not work. DC current is not going to transfer from one coil to another. It has to be alternating current as it is only a changing magnetic field that can couple energy through induction.
The Arduino does not have enough current sourcing capability to get any appreciable power across an air-core transformer. So you will at least need a transistor (or similar) power amplifier attached to the Arduino. Then, this is followed by lots of coils of magnet wire to form the primary. The secondary would be lots of coils of magnet wire connected to an LED.
Lots of design work here: sizing the magnet wire, computing its resistance, figuring out how many turns you can get for a given resistance/current flow, etc. etc. Or you can just try it
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The Quick Shield: breakout all 28 pins to quick-connect terminals
Interesting. I've been thinking about much the same thing recently. In my mind, the best approach will be a ferrous core in the primary, and having a primary that is heavily powered as well as a fair number of turns, to maximize the field strength. My field should be powerful enough to suspend around a half pound at a distance of several inches, for my project to work. That's a powerful magnetic field, a secondary powerful enough to light an LED SHOULD be possible.
I have been thinking about building a maglev rig (electromagnet vs gravity, arduino controlling magnet, on/off sensed with phototransistor in suspension location) and was thinking about much the same thing- could the suspension field be harnessed and rectified and used to drive an LED (or skip rectifier and let LED do it itself-- it is a light emitting DIODE).
Since the electromagnet (which will work better than a total air-core because of the ferrous center) sets up field of pretty decent power, it should be a pretty decent primary. (this assumes design to use AC to drive magnet- I'm thinking Triac- and though original mental design was on/off, PWM could work too..hmm...).
If I assemble the magnet and power it up, I should be able to make and test various secondary coils with a meter, and simply find the right coil by shooting in the dark and tweaking, at least that is the plan... and end up with a Maglev wirelessly powered LED..
Actually, Mike.. it's been done before, in many different ways. Here's a youtube clip of someone who has basically made a smaller-scale version... though not that much "smaller" in scale than my thoughts: Mag Lev - YouTube
In fact, the kid is using an Arduino and PWM to control it.. looks like someone beat me to it quite nicely. Still, won't necessarily stop me from making mine.. and maybe some improvements..
The most basic form operates by just finding the "sweet spot" of an electromagnet running on pulsed DC... pulse the DC at the right freq, and the magnet pulls up and drops the ferrous "load", suspending it against gravity as the coil is cycled on and off. In his (and the design I was thinking of), the field is either modulated or switched rapidly enough that the rise and fall of the field is somewhat smoothed out- you don't SEE the rise and fall-but it's there. In fact, I think I remember an original design (may have even been a Tesla design) where the pulses are made by a mechanical vibrator- a relay that acts as a flip-flop- and that design was OLD.. So, to answer your question, I haven't done the specific calcs for my plan yet, but they are well within reasonable limits, and have been done by amatuers and students many many times.. not to mention I suspect there's more than a few designs of magnetic bearings in use industrially that are similar.
I wonder if we could use a few hall effect transistors, a pulsed electromagnet, and some signal conditioning to build a poor-man's MRI...
es I have seen it done before, I am not saying that it can't be done I am saying that scaling up to the size that you want to go to will not be very practical. You have problems with the core saturating at high fields limiting the field strengths you can get. Also high voltage / currents will be needed to lift half a pound at several inches. The force from a magnet drops off as the inverse cube of the distance. I have worked with big research magnets an know the sort of power involved in driving them.
Well, I couldn't find the one I was looking for.. but I had seen a version controlled by an op amp circuit with a triac and CDS sensor which was suspending a 20 oz claw hammer at about a foot.. and it was being run off the mains on a wall socket- so it couldn't be pulling more than 15-20A @ 120v or it would trip the breakers. Judging by that alone, which is orders of magnitude larger field required - it may be a power pig and not very practical.. but possible, indeed. Mine (and the author of the thread's) goals are a LOT less ambitious.. if his coil, led and such weighed in at an ounce, I would be suprised. In fact, I don't see him wanting the maglev at all, only current transfer.. I'm the dope who threw maglev into the mix... hehehe
Since he only wants to power an LED inductively, a couple of volts at a few mA, he might be able to get away with PWM and a power transistor for his setup, right? If it were me (bad ideas abound), I'd make the primary and just fudge out the secondary as needed. Yeah, I know there's math. You don't need math until you've blown off ALL of your fingers. Until then, it's a matter of doing everything in base "x", where x is the number of remaining digits, pun intended.
So there is pretty much no way to get this with Arduino correct? Or can I use something to do it. Any wiring examples (and would it need some special code?)
Rich- actually, I think that's a beam/sensor photo arrangement. Seems to be the "standard" for the current generation of these things. I was thinking of using one at the bottom of the object suspension, but the idea is the same and much easier to pull off from above.
We really ought to move this discussion to another thread however.. I'm posting this as a bump, because he still needs some help. I know enough to be dangerous, but there are plenty of folks here that can help him.
In summary (as far as I can see) he wants to drive a primary coil controlled by an Arduino pin, with a secondary as an air core transformer, to drive an LED. My best shot at this would be a Triac, winding a primary, and simply finding a decent secondary winding by experimentation, as there's so many variables.
However, there's probably a better way- so jump in, guys!
