Important detail: there's something I did not explain right. When a metal object approaches the transmitter, it does produce an opposing field, *however* the transmitter coil will experience an increase in current that compensates for this, so that the net field remains the same. Just like in a transformer: drawing more current on the output also causes more current draw on the input. For this reason, if your receicer coil was identical to your transmitter coil, and placed exactly on top of it, it would see no change in the field. The key then, is that the receiver coil is shaped differently, has a different size, or is placed in a different location. Although the metal object doesn't change the net field through the primary, it does change the field locally. (in other words, the shape of the magnetic field). Therefore the pickup coil needs a shift in position, a different size or a different shape. I did not go into the importance of the coil geometry/placement well enough in this video, and plan to do this in a revisit later on. Thank you for watching!
Awesome! This is the explanation I was looking for. The others that pop up in my search results just end up hinting they don't exactly know how the detectors work. I'm a technical person, the moment you mentioned signal generator, receiver and alternating magnetic field, I kind of know where it's going. Great that you even have a demonstration!
How does the oscillating frequency from the transmitting coil affect the function of the device? Would a frequency above human audio range be better, with the receive signal being fed through a frequency divider to enable the operator to hear?
It depends on the range required/the size of the objects etc what's best. Normally the lowest frequency they operate at is about 10kHz, which you could technically hear, but it's a very sharp, annoying high pitched whine, so usually, even at lower (audible) frequencies, the tone the operator hears is not the carrier signal itself but indeed something derived from it.
What a horrible explanation. 1. You demonstrated a de-tuning effect of a coil near a metal object. Not how modern two coil detectors work. 2. You should have a second pobe on the TX coil to trigger the oscilloscope trace for the timing of the rx coil. 3. This would allow you to null the rx coil so that the signal strength is near zero. 4. Place metal near the coils and you could witness the signal strength and the phase change on the rx coil. 5. This would demonstrate the ability to detect size and depth on a metal as well as its conductivity for a generalized identification of metal and size/depth. keep learning.
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Important detail: there's something I did not explain right. When a metal object approaches the transmitter, it does produce an opposing field, *however* the transmitter coil will experience an increase in current that compensates for this, so that the net field remains the same. Just like in a transformer: drawing more current on the output also causes more current draw on the input. For this reason, if your receicer coil was identical to your transmitter coil, and placed exactly on top of it, it would see no change in the field.
The key then, is that the receiver coil is shaped differently, has a different size, or is placed in a different location. Although the metal object doesn't change the net field through the primary, it does change the field locally. (in other words, the shape of the magnetic field). Therefore the pickup coil needs a shift in position, a different size or a different shape.
I did not go into the importance of the coil geometry/placement well enough in this video, and plan to do this in a revisit later on.
Thank you for watching!
Awesome! This is the explanation I was looking for. The others that pop up in my search results just end up hinting they don't exactly know how the detectors work. I'm a technical person, the moment you mentioned signal generator, receiver and alternating magnetic field, I kind of know where it's going. Great that you even have a demonstration!
Love that you explain things without dumbing them down.
Thank you very much my friend
Awesome explanation! Made it very easy to understand... Thanks!
Thanks man !
great vid.. thank you..
hi, you should have try to moove the reciever coil so it bearly pick the signal, you would have a much better sensitivity
How does the oscillating frequency from the transmitting coil affect the function of the device? Would a frequency above human audio range be better, with the receive signal being fed through a frequency divider to enable the operator to hear?
It depends on the range required/the size of the objects etc what's best. Normally the lowest frequency they operate at is about 10kHz, which you could technically hear, but it's a very sharp, annoying high pitched whine, so usually, even at lower (audible) frequencies, the tone the operator hears is not the carrier signal itself but indeed something derived from it.
What if someone hide aluminium cloth in the layer of his pocket fabric to confuse and make fun of security guard 😂😂
While it could be funny, I personally wouldn't spend any more time at airport security than necessary 😅
great channel 👍
Very good video, have you recived a pice of gold ? ;)
I wish haha
👌🏼
Al U Minium... amazing... but will it work on aluminum... thats the real question.!
What a horrible explanation.
1. You demonstrated a de-tuning effect of a coil near a metal object. Not how modern two coil detectors work.
2. You should have a second pobe on the TX coil to trigger the oscilloscope trace for the timing of the rx coil.
3. This would allow you to null the rx coil so that the signal strength is near zero.
4. Place metal near the coils and you could witness the signal strength and the phase change on the rx coil.
5. This would demonstrate the ability to detect size and depth on a metal as well as its conductivity for a generalized identification of metal and size/depth.
keep learning.
Hi need your contact number
Your explanation is way too technical. I give your video a thumbs down .
Thanks man !