@@NickFoxQuixand Haha that's fine, but I haven't had to do that up to this point. I'd have used screws normally but they're metal. I think plastic screws or something similar are an option too, but I was lazy so just glued it shut. This glue is usually not too strong to remove anyway.
Thanks for that. You make it look so simple. The basic principle appears to be that of a coreless transformer where the secondary coil is placed so that any clockwise magnetic field is canceled by an equal anti-clockwise magnetic field making the current zero. When a metal object comes close to the magnet field, the magnetic field is distorted which upsets the balance and generates a current in the secondary coil. Hmmm, interesting!
@@cyber5515 what's also cool is that with additional circuitry, you could also compare the phase shift between the receiver and transmitter, which allows you to (up to a point) distinguish between different metals.
Great video. Very informative. I have an inductive sensor that I took apart to see how it worked, but the design made my head hurt; maybe you can explain it. It's a 2-coil design but the coils are different sizes, different values, and the smaller one is positioned inside and off-center of the larger coil. What on earth are they doing??
@@kenengel620 Plenty of metal detectors with 2 coils use non-DD placement of the coils. The same principle can still be used; a metal object will change the shape of the transmitter field, which changes the flux through the receiver coil, and creates a variation in the output signal. However, with the coils arranged like this, you won't have the "normally zero" output signal. There will be some significant continuous output even when no metal is present, which the electronics need to take care of.
@@AKIOTV So, if you wanted to use a double-D and a PCB for the coils, you could conceivably put each coil on opposite sides of the board to achieve the overlap; but does the distance between them make a difference? Would it be better to use a thicker or thinner PCB?
@kenengel620 This is tricky because as you can see in the video, the amount of overlap needs to be exactly right to get an output near 0. But on a PCB you have no room to correct/move things about, you'd have to nail it first try. You would have to calculate exactly what the overlap needs to be, probably using magnetic field simulations. Personally I'd try to make the coils exactly to scale out of regular wire, so you have a testing setup to determine the ideal overlap, which you can then use in a pcb layout. The board thickness I don't think is very critical (depending on the size of the coils) but the thinner the board, the more similar it will be to a pure 2d plane (with no vertical distance), which could simplify the design, especially if you attempt to go the theoretical way.
@AKIOTV You'd be surprised how cheap you can get a PCB made these days. I used to order all my boards, but I can make 2-layer boards now, so that's not a big deal. Also, I'm using an online simulation tool from TI to get as close as possible the first time, but I intend to make 3 or 4 at various amounts of overlap and see how accurate the simulation is. I can get PCB copper clad in varying thicknesses, hence the question does the distance between matter significantly? We're only talking a 0.5mm - 1.0mm difference in thickness. Thanks for the response! Good stuff! Liked and subscribed.
@@kenengel620 Say you have 2 super small coils with a 5mm diameter; a 1mm board thickness would be relatively big, but for a 10cm coil it's nothing. So it depends on the size of the coils how much of a difference it makes. Theoretically, thinner is never worse, so if there are no other reasons to use thicker boards (cost, physical strength etc.) I'd just pick the thinnest option.
@@benholroyd5221 I don't know. I took my (bigger) stuff to a bin, though I have to admit I did throw the glass jars into a "regular" one rather than a glass-recycle bin.
Neat project and very well explained. Thanks!
great channel ❤ thanks for your efforts.
Very nice project.
If doing projects like this has taught me anything, you'll be opening that boxed you glued together pretty soon.
@@NickFoxQuixand Haha that's fine, but I haven't had to do that up to this point. I'd have used screws normally but they're metal. I think plastic screws or something similar are an option too, but I was lazy so just glued it shut. This glue is usually not too strong to remove anyway.
Awesome project dude, great video
Thanks for watching 👍
Thanks for that. You make it look so simple. The basic principle appears to be that of a coreless transformer where the secondary coil is placed so that any clockwise magnetic field is canceled by an equal anti-clockwise magnetic field making the current zero. When a metal object comes close to the magnet field, the magnetic field is distorted which upsets the balance and generates a current in the secondary coil. Hmmm, interesting!
@@cyber5515 what's also cool is that with additional circuitry, you could also compare the phase shift between the receiver and transmitter, which allows you to (up to a point) distinguish between different metals.
Nice !
Great video. Very informative. I have an inductive sensor that I took apart to see how it worked, but the design made my head hurt; maybe you can explain it. It's a 2-coil design but the coils are different sizes, different values, and the smaller one is positioned inside and off-center of the larger coil. What on earth are they doing??
@@kenengel620 Plenty of metal detectors with 2 coils use non-DD placement of the coils. The same principle can still be used; a metal object will change the shape of the transmitter field, which changes the flux through the receiver coil, and creates a variation in the output signal. However, with the coils arranged like this, you won't have the "normally zero" output signal. There will be some significant continuous output even when no metal is present, which the electronics need to take care of.
@@AKIOTV So, if you wanted to use a double-D and a PCB for the coils, you could conceivably put each coil on opposite sides of the board to achieve the overlap; but does the distance between them make a difference? Would it be better to use a thicker or thinner PCB?
@kenengel620 This is tricky because as you can see in the video, the amount of overlap needs to be exactly right to get an output near 0. But on a PCB you have no room to correct/move things about, you'd have to nail it first try. You would have to calculate exactly what the overlap needs to be, probably using magnetic field simulations. Personally I'd try to make the coils exactly to scale out of regular wire, so you have a testing setup to determine the ideal overlap, which you can then use in a pcb layout.
The board thickness I don't think is very critical (depending on the size of the coils) but the thinner the board, the more similar it will be to a pure 2d plane (with no vertical distance), which could simplify the design, especially if you attempt to go the theoretical way.
@AKIOTV You'd be surprised how cheap you can get a PCB made these days. I used to order all my boards, but I can make 2-layer boards now, so that's not a big deal. Also, I'm using an online simulation tool from TI to get as close as possible the first time, but I intend to make 3 or 4 at various amounts of overlap and see how accurate the simulation is.
I can get PCB copper clad in varying thicknesses, hence the question does the distance between matter significantly? We're only talking a 0.5mm - 1.0mm difference in thickness.
Thanks for the response! Good stuff! Liked and subscribed.
@@kenengel620 Say you have 2 super small coils with a 5mm diameter; a 1mm board thickness would be relatively big, but for a 10cm coil it's nothing. So it depends on the size of the coils how much of a difference it makes. Theoretically, thinner is never worse, so if there are no other reasons to use thicker boards (cost, physical strength etc.) I'd just pick the thinnest option.
I would hope that theres some kind of metal detectorists code that says you should take stuff to the bin rather than throwing them on the floor
@@benholroyd5221 I don't know. I took my (bigger) stuff to a bin, though I have to admit I did throw the glass jars into a "regular" one rather than a glass-recycle bin.
I think you should make more vids. they are really good. Just don't turn into michael reeves
There's a name I haven't heard for a while..