I tried finding Hidden Gems on AliExpress AGAIN! (Part 15)
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Date: 2025-08-02
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Comments and reviews: 20
Ron-pe4bp
At 9: 19 you spin the magnet around an axis parallel to axis of your solenoid / coil.
You don't get much of a signal, right
That's because spinning the magnet around that axis can't change the flux through your coil.
To get a voltage from the coil, you need to change the magnetic flux going through the coil.
To do that you would need to rotate the magnet's N-S axis around some axis that is not parallel to the axis of your solenoid.
The best is to rotate the NS axis of the magnet around some axis that's perpendicular to it and also perpendicular to the axis of the coil.
That way, the flux 'cut' by your coil is completely reversed every time the magnet turns 180 degrees.
Unfortunately of course, your drill doesn't fit inside your solenoid in that orientation.
Luckly, the magnet need not be inside the coil - only its flux needs to be.
Hold the magnet with the drill so it's NS axis wll rotate when the drill turns.
The NS axis of the magnet can't be parallel to the axis of rotation of the drill.
Find out if your magnet is magnetized axially or diametrically.
Attach the magnet to the drill so that the NS axis is perpendicular to the drill's rotation axis.
With the drill pointing perpendicular to the axis of the coil and the magnet near the end of the coil, run the drill.
I got 120 mV peak to peak using 2 12-mm neodymium disks and the higher speed of my dewalt hand drill.
My coil was about 6 m of 22 awg solid wire wound around a spool with diameter 30mm and 16mm long.
I used a capacitor (1000 pF or so) to reduce environmental noise.
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At 9: 19 you spin the magnet around an axis parallel to axis of your solenoid / coil.
You don't get much of a signal, right
That's because spinning the magnet around that axis can't change the flux through your coil.
To get a voltage from the coil, you need to change the magnetic flux going through the coil.
To do that you would need to rotate the magnet's N-S axis around some axis that is not parallel to the axis of your solenoid.
The best is to rotate the NS axis of the magnet around some axis that's perpendicular to it and also perpendicular to the axis of the coil.
That way, the flux 'cut' by your coil is completely reversed every time the magnet turns 180 degrees.
Unfortunately of course, your drill doesn't fit inside your solenoid in that orientation.
Luckly, the magnet need not be inside the coil - only its flux needs to be.
Hold the magnet with the drill so it's NS axis wll rotate when the drill turns.
The NS axis of the magnet can't be parallel to the axis of rotation of the drill.
Find out if your magnet is magnetized axially or diametrically.
Attach the magnet to the drill so that the NS axis is perpendicular to the drill's rotation axis.
With the drill pointing perpendicular to the axis of the coil and the magnet near the end of the coil, run the drill.
I got 120 mV peak to peak using 2 12-mm neodymium disks and the higher speed of my dewalt hand drill.
My coil was about 6 m of 22 awg solid wire wound around a spool with diameter 30mm and 16mm long.
I used a capacitor (1000 pF or so) to reduce environmental noise.
reply
zodiacfml
nice find on that tiny blower but the price. this can also double as a personal fan in hot regions however it appears it is single speed and doubt the tiny batteries will last more than 10 min.
10: 00 the price is similar in our country but aliexpress has highre prices (which is in the shipping cost) since they sell to wealthy countries
coincidentally, I received two copies of Mili tracker just yesterday! I think the card is bigger vs the tag or coin version. as explained in the video, it doesn't work well in wide open areas where there is no bluetooth android device (last location is always where it found bluetooth using the location of someone's phone. however, I found the best case scenario a few hours ago while walking in public. I was following this mother and child and the tracker updates almost every few seconds like GPS! It appears it is realtime if consntantly connected! I guess the tracker sleeps if is disconnected to bluetooth and wakes up every 5-10 minutes to check.
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nice find on that tiny blower but the price. this can also double as a personal fan in hot regions however it appears it is single speed and doubt the tiny batteries will last more than 10 min.
10: 00 the price is similar in our country but aliexpress has highre prices (which is in the shipping cost) since they sell to wealthy countries
coincidentally, I received two copies of Mili tracker just yesterday! I think the card is bigger vs the tag or coin version. as explained in the video, it doesn't work well in wide open areas where there is no bluetooth android device (last location is always where it found bluetooth using the location of someone's phone. however, I found the best case scenario a few hours ago while walking in public. I was following this mother and child and the tracker updates almost every few seconds like GPS! It appears it is realtime if consntantly connected! I guess the tracker sleeps if is disconnected to bluetooth and wakes up every 5-10 minutes to check.
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KeksTieger
Very nice video. But it would be great when you could test a few cheap china tools for an electric laboratory. You already tested a cheap oscilloscope but there are many other ones for under 100 and 400 are too much for the most students. And some laboratory power supply unit with constant current mode would be very nice too. I'm very careful to use Chinese products on a socket, but maybe there is something with USB-C. Just a few ideas for a video when you don't have naught for yourself and would be very helpful for me
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Very nice video. But it would be great when you could test a few cheap china tools for an electric laboratory. You already tested a cheap oscilloscope but there are many other ones for under 100 and 400 are too much for the most students. And some laboratory power supply unit with constant current mode would be very nice too. I'm very careful to use Chinese products on a socket, but maybe there is something with USB-C. Just a few ideas for a video when you don't have naught for yourself and would be very helpful for me
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Kraaketaer
About the airflow of that pump, you can never expect to match factory airflow measurements for any kind of air moving device without also having the kind of test setup they use. Airflow testing is incredibly complex, and a small measurement device like the one you used there leaves far too many variables uncontrolled for a comparable reading. If you're curious about this, go take a look at GamersNexus' years long saga of acquiring, learning to use, and developing a methodology for an industrial fan tester.
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About the airflow of that pump, you can never expect to match factory airflow measurements for any kind of air moving device without also having the kind of test setup they use. Airflow testing is incredibly complex, and a small measurement device like the one you used there leaves far too many variables uncontrolled for a comparable reading. If you're curious about this, go take a look at GamersNexus' years long saga of acquiring, learning to use, and developing a methodology for an industrial fan tester.
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johnmeneses7039
AliExpress is a bunch of thieves. Over a year ago I bought something worth $95. 00 from them. Until today I have not received it. They keep indicating that it is at my local post Office. Absolute Rubbish as I have email proof that it was never received in my country by my postal service. I have repeatedly sent them this, yet they reject my proof and refuse to resend or refund. I have the proof, NEVER TRUST ALIEXPRESS.
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AliExpress is a bunch of thieves. Over a year ago I bought something worth $95. 00 from them. Until today I have not received it. They keep indicating that it is at my local post Office. Absolute Rubbish as I have email proof that it was never received in my country by my postal service. I have repeatedly sent them this, yet they reject my proof and refuse to resend or refund. I have the proof, NEVER TRUST ALIEXPRESS.
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-Oleg1
13: 15 You have forget about self discharge, so 7. 5 uA if it has 5% self-discharge (if it is not grade-B/C) per month gives us following: (7. 524)uA = 31. 5uA - avarage discharge rate that consists of battery self-discharge and device sink. 100mA/ 0. 031. 5mA = 3174 hours / 132 days / 4. 7 month. But it doesn't include that self-discharge reduces with reducing charge, also as reducing it's maximum capacity
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13: 15 You have forget about self discharge, so 7. 5 uA if it has 5% self-discharge (if it is not grade-B/C) per month gives us following: (7. 524)uA = 31. 5uA - avarage discharge rate that consists of battery self-discharge and device sink. 100mA/ 0. 031. 5mA = 3174 hours / 132 days / 4. 7 month. But it doesn't include that self-discharge reduces with reducing charge, also as reducing it's maximum capacity
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charlesjmouse
AliExpress is so frustrating.
So many genuinely useful ideas, often at prices you won't see anywhere else. But I'm almost certain every seller's baseline attitude is, Of course it's ok to rob customers. It's up to them to ensure they aren't being cheated.
Even with great care I have a roughly 50% return rate - AliExpress itself rarely argues, it must cost them a fortune!
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AliExpress is so frustrating.
So many genuinely useful ideas, often at prices you won't see anywhere else. But I'm almost certain every seller's baseline attitude is, Of course it's ok to rob customers. It's up to them to ensure they aren't being cheated.
Even with great care I have a roughly 50% return rate - AliExpress itself rarely argues, it must cost them a fortune!
reply
cajuncoinhunter
I use AliExpress to buy certain things like tools and Marine grade heat shrink, certain parts, project boxes. Today I got a Heavy duty PD Type C cord for my portable Kaiweets soldering iron for 3 bucks, Kaiweets want 20 USD. 4MM wheat bulbs 12 volt 50 for 1. 50 USD. I will but certain SMD SOT23 Mosfets from my trusted stores. It's hard to counterfeit those parts.
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I use AliExpress to buy certain things like tools and Marine grade heat shrink, certain parts, project boxes. Today I got a Heavy duty PD Type C cord for my portable Kaiweets soldering iron for 3 bucks, Kaiweets want 20 USD. 4MM wheat bulbs 12 volt 50 for 1. 50 USD. I will but certain SMD SOT23 Mosfets from my trusted stores. It's hard to counterfeit those parts.
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MarioStoilov-q2e
QR codes are an open standard. Literally encoded text and in this case, thext is probably: some_data. What you can do is: generate a new QR code with any random generator on the internet in the format of a contact that Andpriod and iPhone can recognise. Print that new QR code and stick it on the old one. Or even, If you get any card/tracker, you can still do this.
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QR codes are an open standard. Literally encoded text and in this case, thext is probably: some_data. What you can do is: generate a new QR code with any random generator on the internet in the format of a contact that Andpriod and iPhone can recognise. Print that new QR code and stick it on the old one. Or even, If you get any card/tracker, you can still do this.
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SparkofMagic
Cool! you got a Rodin Coil! can you please do more tests with it You have used it backwards, you suppose to put sound into it and it should create a magnetic fields that should be shaped as the magnetic field of the earth, some even say that it has healing properties to the human body: ) I would love to see what it emits if you put amplified sound into it.
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Cool! you got a Rodin Coil! can you please do more tests with it You have used it backwards, you suppose to put sound into it and it should create a magnetic fields that should be shaped as the magnetic field of the earth, some even say that it has healing properties to the human body: ) I would love to see what it emits if you put amplified sound into it.
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xKatjaxPurrsx
Why couldnt' they have put castellated connections on that battery charger so you could just use it as a module to drop on another pcb like what good is it to have this tiny usb-c female connector with no screw holes or any way to fasten it down/inside something are you supposed to just epoxy it into place inside your project too small.
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Why couldnt' they have put castellated connections on that battery charger so you could just use it as a module to drop on another pcb like what good is it to have this tiny usb-c female connector with no screw holes or any way to fasten it down/inside something are you supposed to just epoxy it into place inside your project too small.
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mattmayfield3520
These Bluetooth finders are often limited by quality of app (eg. The OS will shut it down to save battery and then you find that the last location was 2 months ago) and the bigger names utilize all users to connect and find your wallet. However very good price and power systems look very good
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These Bluetooth finders are often limited by quality of app (eg. The OS will shut it down to save battery and then you find that the last location was 2 months ago) and the bigger names utilize all users to connect and find your wallet. However very good price and power systems look very good
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Charlottica
Idea: What if you made a Macrowave using magnetocaloric materials for heating instead of microwaves You could repurpose the shell of an old microwave for the body. Could be a safer and cooler alternative to traditional microwave ovens! Plus, you could also freeze stuff quicker than a fridge too!
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Idea: What if you made a Macrowave using magnetocaloric materials for heating instead of microwaves You could repurpose the shell of an old microwave for the body. Could be a safer and cooler alternative to traditional microwave ovens! Plus, you could also freeze stuff quicker than a fridge too!
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avinci3116
Please don’t buy cheap tracking devices. Either they literally track you and sell the data or the data server gets breached. A lot of homes get robbed because of these security breaches. They are often extremely poorly coded and every half smart high schooler could hack these clouds
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Please don’t buy cheap tracking devices. Either they literally track you and sell the data or the data server gets breached. A lot of homes get robbed because of these security breaches. They are often extremely poorly coded and every half smart high schooler could hack these clouds
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arievanzon
The specified airflow of compressors is usually measured at the suction side at atmospheric pressure.
Compression reduces the flow at the output side, depending on the pressure. So when you hold your measuring fan in the output airstream, the pressure will rise and the flow drop.
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The specified airflow of compressors is usually measured at the suction side at atmospheric pressure.
Compression reduces the flow at the output side, depending on the pressure. So when you hold your measuring fan in the output airstream, the pressure will rise and the flow drop.
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eropis
Regarding the card. These kind of thing stand and fall with the amount of users. Its essentially an apple air tag that only works because apple and samsung now to are so widespread. I wonder if the card hijacks that service. I cant believe it gets picked up by other phones otherwise.
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Regarding the card. These kind of thing stand and fall with the amount of users. Its essentially an apple air tag that only works because apple and samsung now to are so widespread. I wonder if the card hijacks that service. I cant believe it gets picked up by other phones otherwise.
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Diehard4077
I wouldn't trade my ts101 and pd power bank, BUT if I didn't need it that often, (i use mine for work) or use it in awkward places, that portable soldering iron would be great. I had a similar m12 that didn't preform great, the iron was rigidly attached to the battery.
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I wouldn't trade my ts101 and pd power bank, BUT if I didn't need it that often, (i use mine for work) or use it in awkward places, that portable soldering iron would be great. I had a similar m12 that didn't preform great, the iron was rigidly attached to the battery.
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greatscott
Rotating a magnet through a coil with a drill isn’t going to do much it needs to be moving into and out of the coil because it needs to cut through the flux. That’s why when you turned the drill on its axis it magically started producing a greater voltage.
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Rotating a magnet through a coil with a drill isn’t going to do much it needs to be moving into and out of the coil because it needs to cut through the flux. That’s why when you turned the drill on its axis it magically started producing a greater voltage.
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crzren
8: 00 Some batteries might drain complete using it has a power hub and wont be able to charge it using the standard battery charge since voltage dropped below threshold. not sure about Makita but Dewalt Batteries not have built in protection will drain completely.
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8: 00 Some batteries might drain complete using it has a power hub and wont be able to charge it using the standard battery charge since voltage dropped below threshold. not sure about Makita but Dewalt Batteries not have built in protection will drain completely.
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greatscott
LEVITATION mag device for 3d prints to make them spin and levitate did u test them most do not spin endlessly or longtime only two round or not at all. would be super kool to see u test them i dont know what to buy to let a 3d print fly or a vase or flowers
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LEVITATION mag device for 3d prints to make them spin and levitate did u test them most do not spin endlessly or longtime only two round or not at all. would be super kool to see u test them i dont know what to buy to let a 3d print fly or a vase or flowers
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