Metal detector aside, I think this was the most clear explanation of how AM gets demodulated. I knew the idea behind AM transmissions and saw the single diode demodulator in a lot of radio schematics, but I never noticed the capacitor after it and I never thought about how the actual demodulation is done. Thank you very much for that bit of knowledge!
I've been wanting to understand metal detectors since i was a kid. Thank you for the explanation! Also love that you wind your own transformers. Another piece of magic. Thanks!
If you are not going better than the chineese then you should really just find a New hobby.. China takes pride in manufacturing the very worst crap in the whole world. If it works, you can be sure that it is not from china.
@@fredriksjoblom5161the Chinese can manufacture to whatever standards you ask. They make cheap crap and they make high quality goods. I laugh at people who sneer at Chinese manufacturing, while they are using high quality phones and computer components made in a China.
@@michaelfisher9671 I was using a "high quality phone" from china. But then it turned out that the chinese used the phone for malicious surveillance (spying basically) and after some statements by mr Donald Trump it became very uncertain as to wether banking and/or comunity services would be available for chinese phones in the future. So when i was shopping for a new chinese phone one day the staff in the store couldn't sell me one without warning me that it was likely going to be rendered useless in the near future, so i quit using chinese phones. Is this what you meant by high quality? You may laugh at me all day, but at least i'm not being ripped off by a criminal country with - wait for it- ...... Shitty manufacturing! =D
@@fredriksjoblom5161 Quite likely a large proportion of consumer items you own were made (or components of them were made) in China. Parts of iphones are made in China. You are not in touch with the reality of 2000's manufacturing
when I was in school I made a 3 coil design. it had the coils wound on a piece of 4 inch PVC. the center coil was the driver and the outer two were in series, but connected out of phase. The result was a unit that could separate diamagnetic materials from magnetic materials.
@@saRah-to1kv nowadays I would design it differently than I did back then.back then it was a pile of transistor amplifiers on a large plug board. It could all be done in a small processor and a couple op amps.
Thank you for making the video. It is very gracious of you. I am glad that you added the audio buzzer. As I understand it, there is an art to using a metal detector and that art is learning what to listen for.
Amazing, I can't wait for the next episode. The sensitivity of your circuit is mutch better than the one from the metal detector I build a while ago. Also I learnd a lot. Have a nice day.
That's actually a really nice solution and circuit. And lots of thought put in ahead of time so there's less trouble later. Initially I winced at the suggestion of an audio alert, but the demonstration looks really useful. I think it's because the detector has to work on changes so the sound will never be a shrill constant annoyance but more like a record scratch. Very nice, looking forward to the next ones!
For audio indication, I would use demodulated voltage and feed it after first or 2nd stage to the 555 set up as an oscillator so it changes the frequency of the tone, also you could use phase comparator section of some PLL IC you have laying around and put 2 LEDs one for ferromagnetic metals and the other one for everything else (at least), it would be a great device capable of beating the pro ones 😜
To mitigate the drift of the receiver you can use two low pass filters. One low pass filter for the demodulated waveform and then another one with a much longer time constant to act as an averaging filter. This way you could feed the output of both filters to a comparator and use the average as a reference and the demodulated output as a trigger. So the circuit would become self-calibrating to an extent.
You are really a genius and you also understand what you construct and are able to explain it to others! Great Job! Magnetic induction and resonance is still a bit of a miracle to me - although i got the general concept :-)
Nice Use opamp for first stage of amplifire. Use 2 input inductor for transmiter instead of center tab transformer and put the tx coil directly. Increase inductance of coil and use frq around 7khz. I have designed several digital metal detectors. Vlf metal detectors are simple and really fun
An interesting project. Perhaps a useful addition would be to have the detected imbalance control the amplitude of an audio tone, but then also add a phase comparator that controls the tone frequency. You'd develop a feel for the audio signature of different objects or metals as you sweep across them. A low transmitter frequency (a few kHz) will likely work best when detecting phase shifts.
Mechanical adjustment of the coils seems tedious and difficult to implement. I wonder if it would be possible to get them as balanced as possible mechanically and then have a fine adjustment on the transmit power to null out minor variation? Is this a worthless idea?
Adjusting the transmit power would not affect the balance, but an adjustable circuit which was fed with two weak antiphase signals from the transmitter could be used to feed a tiny correcting signal into the receiver. An easier technique would be a very small adjustable metal screw somewhere in the head assembly, whose presence and positioning compensated for the imbalance.
Its a very interesting design but I was wondering if you considered using probably one of the oldest metal detection designs. Basically its two LC-oscillators for the same frequency (couple of 100KHz), one has its coil as a large search coil on a wand/stick. The coil of the 2nd oscillator is small and shielded inside the detector housing. The output of the two oscillators is mixed and amplified to headphones. If the two osc. have the same frequency you get nearly no tone but the more the frequency differ even slightly you get a tone with increasing frequency. This happens when the search coil gets into the vicinity of metal because it changes the inductance and therefore the frequency of that osc. If you adjust the freq. to differ just a little so that you hear a steady tone with no metal, you can even detect if the material is ferro-magnetic or not because one will make the tone freq. sink and the other rise.
Thank you very much That's a huge work There is a nice schematic using a double 555 timer or a single 556. I tried it my self. But I always have a problem on the winding part
looks so promising, specially at the end when you showed the audible indicator, which is light-years away better than that crappy buzzer from the chinese board (which thankfully you got rid of!). I really want to know how far it could possibly detect metals and if there's a way to focus the beam (like using some directional antenna radiator optimized for the same frequency); Also, if you increase the sensitivity too much to get metal objects from far distance, does it get interfered by unwanted metals like iron in your blood? 😜
Less than 0.07% of blood is iron, and it lacks most properties of metallic iron when forming compounds like hemoglobin. Also, the pulsing within arteries corresponds to small volume changes, so he would need to move to set off the AC-only detector (even if it was possible). The circuit is more likely to be disrupted by vibrations (as shown in the video) or EM interference from mains or other electronics.
Вообще можно использовать еще импульсную схему и улавливать отовжение чигналв от объекта, тогда по разности в фазе сигналов можно обнаружить и определить приблизительне расстояние до обьекта.
Don't forget that those breadboards have high stray capacitance. You are also waisting 50% of the transmission power, use passive reflector, and parasitic radiator. After all, you are building a radio and antenna. The best discriminater is the human ear, make the output Audio and use Hi-Q headphones. Give some thought to using higher frequencies and superhetrodyne.
ALL metals , have a free electron like the outer most electron of the copper wire. the "free" electron in copper requires less magnetic force to move it, than in other low cost metals. Insulator atoms requires huge, tremendously large magnetic forces to move electrons , hence can create only very tiny miniscule current flow.
Wondering if anyone could help me out. I replicated the circuit but im having problems. The reciever part seems to be working fine, since when i touch the reciever coil input, the led blinks(probably from the 60hz mains interference) but the oscillator circuit seems to not work at all. I did use different transistors but I don't think thats the problem
I have no modicum of doubt that this video will turn out to be impressive. You are indeed great with excellent teaching skill. On a closer look at the receiver circuit, I was persuaded to ask: (1). How would I modify the receiver circuit to achieve a neat AM radio receiver ? (2). Is it possible to also use any of the circuits to build my own analogue TV transmitter ?
Lm555 and bc327 its not pound we cant other ic and transistor using this circuit please tell me sir this circuit wiring diagram description is your video
I think there is maybe an error in the transmitter schematic. The value for transformer primary inductance should be probably 0.39 mH, not uH. I simulated this circuit in LTspice and it oscillates on 177kHz, way too high. Also, 0.39 mH at 44 turns would result in AL = 200 nH/turn2 for the transformer core, which is more realistic value.
YAY, you actually built that, i also built it, and found cool stuff with it!! one thing i was looking for is how to make it more powerful ... btw i built the 555 version, i might try your version, looks like it works better :)
@@saRah-to1kv you should be able to find it by searching google, and I'm already going to tell you, Diodegonewild's version is wayyyy better than the 555 version
I would definitely choose a 3D printed coil holder instead of using resin. If it goes wrong, you can change the 3D design and try again. If you use resin then good luck trying to salvage/reuse the coils.
Metal detector aside, I think this was the most clear explanation of how AM gets demodulated. I knew the idea behind AM transmissions and saw the single diode demodulator in a lot of radio schematics, but I never noticed the capacitor after it and I never thought about how the actual demodulation is done. Thank you very much for that bit of knowledge!
Now thats a serious metal detector. I'm really looking forward to the next episode!
I've been wanting to understand metal detectors since i was a kid. Thank you for the explanation! Also love that you wind your own transformers. Another piece of magic. Thanks!
I'm glad you've desoldered the buzzer!
Crazy how your first prototype is already 10 times more sensitive than the chinese one :)
its not crazy, its expected
If you are not going better than the chineese then you should really just find a New hobby.. China takes pride in manufacturing the very worst crap in the whole world. If it works, you can be sure that it is not from china.
@@fredriksjoblom5161the Chinese can manufacture to whatever standards you ask. They make cheap crap and they make high quality goods.
I laugh at people who sneer at Chinese manufacturing, while they are using high quality phones and computer components made in a China.
@@michaelfisher9671 I was using a "high quality phone" from china. But then it turned out that the chinese used the phone for malicious surveillance (spying basically) and after some statements by mr Donald Trump it became very uncertain as to wether banking and/or comunity services would be available for chinese phones in the future. So when i was shopping for a new chinese phone one day the staff in the store couldn't sell me one without warning me that it was likely going to be rendered useless in the near future, so i quit using chinese phones. Is this what you meant by high quality? You may laugh at me all day, but at least i'm not being ripped off by a criminal country with - wait for it- ...... Shitty manufacturing! =D
@@fredriksjoblom5161 Quite likely a large proportion of consumer items you own were made (or components of them were made) in China. Parts of iphones are made in China. You are not in touch with the reality of 2000's manufacturing
when I was in school I made a 3 coil design. it had the coils wound on a piece of 4 inch PVC. the center coil was the driver and the outer two were in series, but connected out of phase. The result was a unit that could separate diamagnetic materials from magnetic materials.
Wow, you made a gold-digger!
Hi can you give me a design i want to make it
@@saRah-to1kv nowadays I would design it differently than I did back then.back then it was a pile of transistor amplifiers on a large plug board. It could all be done in a small processor and a couple op amps.
Thank you for making the video. It is very gracious of you. I am glad that you added the audio buzzer. As I understand it, there is an art to using a metal detector and that art is learning what to listen for.
Amazing, I can't wait for the next episode. The sensitivity of your circuit is mutch better than the one from the metal detector I build a while ago. Also I learnd a lot.
Have a nice day.
That is so cool. I'll add it to my 'build it' list.
That's actually a really nice solution and circuit. And lots of thought put in ahead of time so there's less trouble later. Initially I winced at the suggestion of an audio alert, but the demonstration looks really useful. I think it's because the detector has to work on changes so the sound will never be a shrill constant annoyance but more like a record scratch. Very nice, looking forward to the next ones!
This circuit is really useful 👍🏻👍🏻
Top man !!
Real metal detector well explained, described and clear schematic
Thank you
Very clever receiver/amplifier. I see the changes you made to the receiver coil connections and think I understand the reason.
For audio indication, I would use demodulated voltage and feed it after first or 2nd stage to the 555 set up as an oscillator so it changes the frequency of the tone, also you could use phase comparator section of some PLL IC you have laying around and put 2 LEDs one for ferromagnetic metals and the other one for everything else (at least), it would be a great device capable of beating the pro ones 😜
As always very informative, big thumbs up...
Big fan from India
To mitigate the drift of the receiver you can use two low pass filters.
One low pass filter for the demodulated waveform and then another one with a much longer time constant to act as an averaging filter.
This way you could feed the output of both filters to a comparator and use the average as a reference and the demodulated output as a trigger.
So the circuit would become self-calibrating to an extent.
Just be careful, you dont want it to start oscillating but it would be a good idea
Love your channel. Your knowledge is priceless my friend. Ty for your time.
Excellent work, it all made a lot of sense, next episode's gonna be great ...cheers.
You are really a genius and you also understand what you construct and are able to explain it to others! Great Job! Magnetic induction and resonance is still a bit of a miracle to me - although i got the general concept :-)
سيد هل يمكن ان تساعدني بخصوص هذا المخطط
Sometimes you make me think "am I real that stupid"? 😅 Great design and explanation as always!
Can it detect the metal pins of the circuit components it is made up of
Good job. I agree with the pet!
Nice
Use opamp for first stage of amplifire.
Use 2 input inductor for transmiter instead of center tab transformer and put the tx coil directly.
Increase inductance of coil and use frq around 7khz.
I have designed several digital metal detectors. Vlf metal detectors are simple and really fun
An interesting project. Perhaps a useful addition would be to have the detected imbalance control the amplitude of an audio tone, but then also add a phase comparator that controls the tone frequency. You'd develop a feel for the audio signature of different objects or metals as you sweep across them. A low transmitter frequency (a few kHz) will likely work best when detecting phase shifts.
At ~10:40 you describe the clipping limit (rail voltage) of the signal amplitude. So... what if you drive at ~48v or 96v? or even higher (>120)?
Mechanical adjustment of the coils seems tedious and difficult to implement. I wonder if it would be possible to get them as balanced as possible mechanically and then have a fine adjustment on the transmit power to null out minor variation? Is this a worthless idea?
Adjusting the transmit power would not affect the balance, but an adjustable circuit which was fed with two weak antiphase signals from the transmitter could be used to feed a tiny correcting signal into the receiver. An easier technique would be a very small adjustable metal screw somewhere in the head assembly, whose presence and positioning compensated for the imbalance.
@@robinvince616 Thanks.
Love the explanation. Thanks!
Really good video again. and thank you for removing the buzzer :D
Really nice work!
That thing is really sensitive
Please ,Can i use a diode 1n4148 or 1n4007 to replace the diode 1n5819 for demodulate a signal
استاذ الكريم ارجو منك اني مبتدئ
كيف تساعدني لاصنع هذا المخطط
Reinventing a wheel )))
Like, as always.
I build very simmular detector with oscilator and transmitter.I can hear signal from detector on AM radio reciver on middle waves 540-1600kHz
You should build an fm transmitter... That would be great!
Its a very interesting design but I was wondering if you considered using probably one of the oldest metal detection designs. Basically its two LC-oscillators for the same frequency (couple of 100KHz), one has its coil as a large search coil on a wand/stick. The coil of the 2nd oscillator is small and shielded inside the detector housing. The output of the two oscillators is mixed and amplified to headphones. If the two osc. have the same frequency you get nearly no tone but the more the frequency differ even slightly you get a tone with increasing frequency. This happens when the search coil gets into the vicinity of metal because it changes the inductance and therefore the frequency of that osc. If you adjust the freq. to differ just a little so that you hear a steady tone with no metal, you can even detect if the material is ferro-magnetic or not because one will make the tone freq. sink and the other rise.
Would you try to use a rodin poe as your antena instead?
Would love to hear this guy have a conversation with Thoisoi.
Could you please explain the transmitter part in more detail?
Hi
I have one question...
Is any thing like red mercury tube is invented really??
Nice video
Thank you very much
That's a huge work
There is a nice schematic using a double 555 timer or a single 556. I tried it my self. But I always have a problem on the winding part
Would it be possible to make a stealth metal detector shoe?
looks so promising, specially at the end when you showed the audible indicator, which is light-years away better than that crappy buzzer from the chinese board (which thankfully you got rid of!).
I really want to know how far it could possibly detect metals and if there's a way to focus the beam (like using some directional antenna radiator optimized for the same frequency);
Also, if you increase the sensitivity too much to get metal objects from far distance, does it get interfered by unwanted metals like iron in your blood? 😜
Less than 0.07% of blood is iron, and it lacks most properties of metallic iron when forming compounds like hemoglobin. Also, the pulsing within arteries corresponds to small volume changes, so he would need to move to set off the AC-only detector (even if it was possible). The circuit is more likely to be disrupted by vibrations (as shown in the video) or EM interference from mains or other electronics.
Because its iron oxide (rust). It's Elemental watson... ;)
Nice project , is the soil magnetic properties can affect the detector sensitivity and can this detector separate the non ferrous metal .
Very nice project and explanations as usual 👍 thank you. 🙏
A dog ?? Where is the cat ? 😂
new breadboard 😄
Very nice job
Very cool project and practical explanation¡¡. I feel greedy on seeing a more powerful transmitter but i guess it would be worse to tune out
Hello, my dear engineer, please make a skeleton so that we amateurs can understand the work, and we can make one from your training.
13:51 How crt oscilloscope work with these digital function
This is super cool!
would be intersting use operational amplifiers instead of transistors for signal amplification, that could give pretty high sensivity
Excellent ❤❤❤
Good job 👌
Why should it detect onky the ac part of the modulation? Why not let the modulation comes out as frequency (probably like most commercial md)?
hola muy buen proyecto,puede compartir los diagramas y componentes del detector?
Вообще можно использовать еще импульсную схему и улавливать отовжение чигналв от объекта, тогда по разности в фазе сигналов можно обнаружить и определить приблизительне расстояние до обьекта.
Thank you.
Awesome! Saving this for later :)
Could you make a very sensitive microphone by putting the detector coil on a membrane?
thank you dgw. we should build your very good circuit and then go looking for gold or other metals.
Niiiiiiiiiiiccccccccccccceeeeeeeeeeeee. =)))))))
This circuit realy Works?
fix the coil and You can make a variable transmitter Frequency with a microcontroller To ensure the stability of the signal
Don't forget that those breadboards have high stray capacitance. You are also waisting 50% of the transmission power, use passive reflector, and parasitic radiator. After all, you are building a radio and antenna. The best discriminater is the human ear, make the output Audio and use Hi-Q headphones. Give some thought to using higher frequencies and superhetrodyne.
Wow, things go to interesting side!
ALL metals , have a free electron like the outer most electron of the copper wire. the "free" electron in copper requires less magnetic force to move it, than in other low cost metals. Insulator atoms requires huge, tremendously large magnetic forces to move electrons , hence can create only very tiny miniscule current flow.
Please make a better version and schematics for it, so i can make it at myself.
Im a fan from 2016
ETI 549 Induction Balance Detector 1977 is good project I built then.
Now we just need some metal to look out for!
Activate the subtitles so that those of us who do not speak your language can understand you better, so you would have more views !!
Wondering if anyone could help me out. I replicated the circuit but im having problems. The reciever part seems to be working fine, since when i touch the reciever coil input, the led blinks(probably from the 60hz mains interference) but the oscillator circuit seems to not work at all. I did use different transistors but I don't think thats the problem
I have no modicum of doubt that this video will turn out to be impressive. You are indeed great with excellent teaching skill. On a closer look at the receiver circuit, I was persuaded to ask: (1). How would I modify the receiver circuit to achieve a neat AM radio receiver ?
(2). Is it possible to also use any of the circuits to build my own analogue TV transmitter ?
I waiting For your video :)
That picture you drew looks like me after I smoked something😂
i love your new jokes, always chuckle
why not use a PNP, NPN Setup? that way in the later stage u could make the leds turn ON instead of OFF when a metal object distords the field.
Lm555 and bc327 its not pound we cant other ic and transistor using this circuit please tell me sir this circuit wiring diagram description is your video
👍
Can i ask whats your nationality? Jsi čech?
I think there is maybe an error in the transmitter schematic. The value for transformer primary inductance should be probably 0.39 mH, not uH. I simulated this circuit in LTspice and it oscillates on 177kHz, way too high. Also, 0.39 mH at 44 turns would result in AL = 200 nH/turn2 for the transformer core, which is more realistic value.
Thanks, you're right, it's 0.39 mH (= 390 uH)
YAY, you actually built that, i also built it, and found cool stuff with
it!! one thing i was looking for is how to make it more powerful ...
btw i built the 555 version, i might try your version, looks like it
works better :)
Hi can you give me the version of 555 i want to make it please
@@saRah-to1kv you should be able to find it by searching google,
and I'm already going to tell you, Diodegonewild's version is wayyyy better than the 555 version
Very nice TY !
In the third episode you show us how you unearthed the treasure of Priamus .
Skús pridať spätnovezobný odpor do emitora prvého tranzistora v detektory pre zlepšenie stability
To sníží citlivost :) spíš tam asi přidám potík v sérii s emitorem, kterym půjde tu citlivost nastavovat.
I would definitely choose a 3D printed coil holder instead of using resin.
If it goes wrong, you can change the 3D design and try again.
If you use resin then good luck trying to salvage/reuse the coils.
another thought would be to use wax instead of resin.
👍👍
Cat ?
Great to see a project that doesn't use a microcontroller.
Great to see somebody who also appreciates analog circuitry :)
@@DiodeGoneWild If you can't work with analog discrete components you don't know shit about electronics.
a lot of people are good at programming microcontrollers, yet they can't calculate the series resistor of an LED :).
@@DiodeGoneWild LMFAO
can you try that device in your garden
Nice.
Nice to see the Jack Russel Dog, ;-)
LMAO, Great video and coil design. The way you speak reminds me of Forest Gump with an accent. Its hilarious .. Great video man
17:12. Some criticism on this project
Nice 👍✌️🙏
centimeterssssss
That's cool
Good video thanks ;)
Here's the dog!