# The Anti-Gravitator Thru-Hole Version

by dewhisna Dec 20, 2016

I used a A 12v psu and the 100uf capacitor exploded does anyone know why that would happen. the polarity is correct

When you say "the polarity is correct", are you referring to the power supply's polarity or the capacitor's polarity? It's important to make certain that both are correct. On the capacitor, did you use a capacitor rated for at least 25V? The line-marking on most electrolytic capacitors marks the negative lead and must be on the side opposite the "+" marked on the silkscreen on the PCB. Though it's possible that some capacitors mark the positive lead instead, so verify it with the datasheet.

Check your power supply with a volt meter to confirm that its polarity is correct. The (+) lead must connect to pin 1 (the square pad) of the power input connector and the (-) lead must connect to pin 2 (the circular pad). Also, make certain you used a DC power supply and NOT AC. An AC power supply very likely could make that capacitor explode, since there are no diodes or bridge rectifiers in the circuit. I haven't done the impedance calculations for that capacitor on an AC input at typical line frequencies, but it will probably appear as a near short-circuit to it, causing the capacitor to get hot and explode. It's also equally bad to connect a DC power supply backwards. So make sure you have a DC power supply and that its polarity is correct.

Next, using a volt meter, verify that your power supply really is 12V as rated. Many, if not most, power supplies are not regulated and supply a lot more than their stamped voltage until sufficiently loaded. Supplying twice its rated voltage isn't uncommon for an unregulated supply. Many battery charger supplies fall into this category. For example, a 12V battery charger likely supplies 18-24 volts with no load on it, and will drop to around 12v only when the load of the battery it's charging is connected. If it's over the voltage rating of the capacitor, that can also cause it to explode.

If all of that checks out, it's possible it was just a bad capacitor...

Hello, I was wondering what magnet ball you used in the photo? any link possible for purchase?

The one I used on mine was this one from Amazon: (https://www.amazon.com/gp/product/B01L5WAIQC/). However, you will probably want to find a magnet that's a bit stronger than that one, perhaps this one: (https://www.amazon.com/gp/product/B00765XDZ6/).

The reason is that you want a good weight to magnetic strength ratio. The one I used in the picture was too much on the weak side. I took that picture still during the assembly/testing phase before I had glued the last ABS 3D part in place at the bottom of the coil assembly. It worked, but had to be quite close to the coil because the magnet is too weak for its weight. Once I glued the last plastic piece in place, it could no longer get close enough to the coil to actually work anymore.

The trick is to find a really strong magnet that's really heavy. If its magnetic strength is too weak for its weight, it has to be too close to the coil and/or the coil won't have enough power to pull it up. However, if the magnet strength is too strong for its weight, such as a really light-weight single neodymium magnet, it's really hard to find the balance point beneath the coil and will likely go flying upward and stick to the bottom of the coil. So you have to have the correct ratio of magnetic strength and weight -- generally something that's quite heavy and really strong magnetically works well. But it requires experimentation.

I do know if you use the magnet sphere I originally used at the first link above, you'll probably be disappointed. I haven't tried the one at the second link yet, but it looks like it might be a better choice.

Hi

All parts arrived including PCB which BTW was really nice and easy to use and build on. Good work!

I did some modifications though to the original thing which can be seen here https://www.thingiverse.com/thing:2222118

Have two of the PCBs left if anyone wants them do let me know.

Cheers!

Antigrav-Levitator
by bortek

I am thinking about ordering the PCB. Can you elaborate more about the coil? What are it's dimensions? Did you 3D print spool too ?

Do you think it can levitate a metal boll, is it it on your picture? Or can it only levitate neodium magnets?

Thanks!

For the coil, I basically followed the instructions on the original design at https://www.thingiverse.com/thing:943091. I 3D printed the parts he had for the coil spool. I used a 1/4"x2" screw instead of the metric bolt, since here in the US that's easier to find. And I used standard 30gauge magnet wire.

I drilled a small hole on the "V3_Spule_Oberteil" piece near the base and threaded the wire through from the inside and taped it down to the "V3_Spule_Unterteil" piece so that it was held in place while winding it. Then I put the screw through the spool pieces and tightened it up. Then I just began winding the wire around the spool. I tried to be neat with it, but it was impossible to get it perfect with one layer exactly over the next, etc. It really doesn't matter a lot as long as you have sufficient wire. I just kept winding until the entire spool was full and the wire was close to flush with the ends of the spool pieces (see the picture I have posted). Then, I wrapped the whole thing with tape to keep it secure.

You want somewhere around 50-ohms on the wire, but you won't really know what it is until you're finished winding. The original design has some guidelines for length of wire, but I didn't have a good way to measure the length so I just filled the spool without measuring nor counting turns or anything. My coil measured 50.8-ohms when done, which is nearly perfect. If it's off, it won't matter a whole lot except if it's too low, it will get overly warm during operation.

It will only levitate magnets. It doesn't necessarily have to be neodymium magnets other types of magnets may be used, but the magnetic strength to weight ratio is what is important and requires experimentation when calibrating it. If the magnet is too weak for the weight, it won't attract strongly to the electromagnet of the coil and will fall down. If the magnet is too strong for the weight, it will attract instantly to the electromagnet coil and stick to it without balancing and "levitating".

It won't work with just a metal ball because of how the entire thing is designed to work. The coil, which functions as an electromagnetic, attracts the magnet to it. The hall-effect sensor senses the increase in magnetic field strength from the magnet being pulled toward the coil and sensor and when the voltage level on the hall-effect passes the voltage level set on the potentiometer, the circuit turns off the coil, which causes the magnet to drop. When it starts to drop, the hall-effect senses the decrease in magnetic field and that causes the circuit to turn the coil back on, which causes it to rise toward the coil again. It senses the increase and turns it back off... and so it oscillates on-and-off at the "sweet spot" distance where the magnetic field strength is balanced against the weight of the magnet trying to fall because of gravity. You can actually feel it vibrating and depending on the surface it's sitting on, you might even hear the hum from it.

A metal ball might be attracted to the electromagnetic of the coil, but won't cause enough change in magnetic field that the hall-effect will sense it. Though you should experiment, as you may find a way to do it. I haven't personally tried that. Maybe a small neodymium magnet with a metal ball too? If the weight to magnetic field of the object is right, you can levitate it.

There's other remixes online where people have placed the magnet inside an object, like a 3D printed plane or something, and made that levitate. In any case, you are balancing the magnetic field strength attracting the object upward against the weight of the object being pulled down by gravity.

Happy building!

Anti-Gravitator

I appreciate an extensive elaboration on the topic and answering my questions. :) I see now that in the original thing it is a ND ball magnet and not just a metal ball. I will get the parts ordered and start building as soon as they arrive.