Magnetic Remote Control

In this video I'll show how I built a remote control that works entirely off the magnetic field of a coil (unlike a typical radio transmitter). This is known as inductive coupling, an is the same principle used in a transformer. The only difference in this case is that the windings of the transformer are very far apart. This type of signaling is common in short-range, low power devices, like RFID.
This is effectively the same setup that would be used for wireless power transfer, but with two key differences:
-The output of the transmitting coil is not a continuous wave; it's modulated to produce a signal
-The signal of the reciever coil is amplified (by about +70 dB)
The transmitter produces a series of damped oscillations at 69 kHz, with a pulse frequency that can be varied between 1.3 kHz and 2.3 kHz.
The reciever circuit the same design as you'd find in a simple AM radio, the only difference being that the frequency used here (69 kHz) is far below the AM band. The reciever extracts the signal tone, and cleans it up through a schmitt trigger to produce a 0-5V square wave. The schmitt trigger output is sent to an Arduino Uno, which reads the tone frequency, and controls a standard R/C toy servo accordingly.
The main advantage of this kind of transmitter is that it can be made to work without the huge antennas or elaborate grounding schemes needed to operate a typical ULF/VLF radio. The disadvantages are that it's very directional (on both the transmitter and reciever end), and the signal amplitude drops off exponentially faster than a typical radio. With an ideal omnidirectional radio transmission, the amplitude drops off with the square of the distance, whereas with inductive coupling, the drop off is approximately the 3.5th power of distance.
Relevant components in these circuits:
-IRLZ44 MOSFET
-NE555 Timer
-2N3904 and 2N3906 NPN and PNP BJT's
-1N4148 Diodes
-LM7805 for 5V Regulation
-15 to 365 pF Variable Capacitor for Reciever Tuning
www.amazon.com/Capacitor-Vari...
Music Used:
Kevin MacLeod - Groove Groove
Kevin MacLeod - George Street Shuffle
Heatley Bros. - Otherworld
Lukrembo - This is for you

[@jdrissel]

If you want a remote for something that will be underground or underwater, this is one of the few options that are practical. If you need a lot more range then you can get from this then you've got to add something like a floating repeater buoy that can receive an RF signal and translate it into a magnetic signal. One practical application I think of is an occupancy sensor for a pool or hot tub...

[@alexandergrimsmo]

Interesting idea for some underwater transmission applications.

[@okapel5096]

Hello. lets exchange contacts. I m also on that quest.

[@klausziegler60]

In this channel I have learned more electronics than studying my books. His explanations are unique in the web. He goes deep into the subject, something nobody does!

[@seditt5146]

Tends to be a sign someone actually understands what they are saying as opposed to looking everything up prior to creating a video then explaining it as though you understood it all alone. Many creators seem to do this and it is quite obvious when you find them parroting basic stuff a quick Wiki search could teach you.

[@alexfunke214]

Not only a very clever circuit, but a superb explanation. Bravo, and thank you!

[@stefano.a]

6:03: Electric and Magnetic fields cannot exists alone, so you are effectively transmitting an electromagnetic wave (with a very big wavelenght). The induction phenomenon itself relies on the presence of electric field (Faraday Neumann Lentz law and Ampere Maxwell law). When you put the second coil near the first (the emitting coil), inside every infinitesimal slice of wire there is the electric field part of electromagnetic wave you are transmitting.

[@alexandergrimsmo]

It is in principle a radio transmitter / receiver, isn't it?

[@CG-rr6yx]

​@@alexandergrimsmo A very pedantic answer is that it is not really a radio transmission system because it does not use radio waves to communicate. Maxwell's equations of the electromagnetic field show that there are two ways the energy of a perturbation leave the generating circuit; at close distance (up to 10 wavelengths) the so-called induced field dominates, which varies very rapidly in amplitude and behaves similar to the field between the coils of a transformer or between the stator and the armature of an electric motor / generator. Further away the electromagnetic energy travels as waves that drop in amplitude more slowly (proportional to the inverse square of the distance) towards the infinite horizons. In our case, for a carrier frequency of 69 kHz (approx. 4.35 km wavelength) at a few metres between the transmitter and the receiver, the signal doesn't act as a radio wave, so it is not a radio communication system.

[@curiousviewer5991]

I love it when you show the circuits and describe how it works!

[@brandonhicks7549]

Filter impedance is what the filter should see. Adding resistors (providing the impedance is what you thought), will each create a voltage divider cutting the voltage in half (6dB x2 =12dB) In other words remove the resistors and that will improve things. It would also be wise to design to the right impedance, which isn’t 1200 ohms.

[@patrickjdarrow]

Awesome demonstration that combines learnings from undergrad circuits + electromagnetics

[@nigeljohnson9820]

There appears to be an error on the receiver circuit diagram. The PNP output transistor is connected with its collector to rail not its emitter. I assume you intended the circuit to operate in a complementary configuration. As drawn, the output transistor permanently bias off.

[@HyperspacePirate]

Yeah that is in fact an error in the schematic. The software I'm using seems to automatically orient a PNP transistor with the collector/emitter swapped and I didn't notice it

[@waynehale66]

Well he noticed well played nigel

[@samuelrj2350]

@@HyperspacePirate Hey, also your caps are labeled with the unit Henries on your first schematic. Awesome video!

[@jacoposerafin7576]

As an electronic engeneering student, I can say one of the best video I've seen on KZbin

[@ralphanderson2099]

I'm a 30+year Diesel mechanic and I understand everything mechanical very well. Electrical is a different animal in that the vocabulary is like a bunch of clicking noise to me. I have to watch and listen very closely to absorb the information you so eloquently spout off in rapid fire. Hahahah. It's sinking in . Thanks for video and I find all this great, very very informative and helpful. Peace.

[@IncroyablesExperiences]

I love your ture engineering, rare quality on KZbin!

[@thobiasmartin4768]

First seconds of the video and I'm already hooked because of the KSP music, great choice

[@fenderrexfender]

my dad once taught me all of this when i was just a kid it has helped me understand cpus and so much more signal processing and all the cool ways to look at waveforms and encryption to man in the middle CB radios

[@antonanton3136]

allthough i know a bit about electronics, I don't understand even half of what he says, but I still love these videos. so relaxing.

[@marketzensperger5214]

Wow, that's very clever. I use the 555 and 556 in model rockets for event execution they have so many uses

[@suryanshtagore7180]

thank you for the amazing explanation.... probably the first video in which bi understood everything.

[@blueredbrick]

Hearing aid induction loop systems are perfect for the function you want to achieve. The modules can be found at second hand stores or thrift stores because old peoples homes used to have installled those systems as well.

[@bmacdoug]

Thank-you. Your explanations are some of the best I have ever encountered - Awesome. And the projects are excellent as well.

[@ibrahim.t3530]

yes the video popped up in the right time i really needed a good simple circuit for transmitting, love it❤❤

[@williamna5800]

Not sure of the 'why' of it, but the coolness factor coupled with description of 'how' is 10/10

[@DronDanDan]

Very clear explanation! Thanks!👍

[@ProjectPhysX]

I used a similar circuit design for a plasma speaker with a flyback transformer. Without a large heatsink, the mosfet would desolder itself after less than a minute :)

[@two_number_nines]

tried to do the same thing when I was 12 years old. used a many-turn coil and 9.6v ni-cd charger to send pulses and recieve them in audio amp with old fluorescent ballast with its core opened. I could make the speaker cradckle every time i turned on the coil up to about 8 meters of range

[@nigeljohnson9820]

I suspect there is considerable scope for improvement to the receiver circuit sensitivity. It might be worth looking at the receiver circuits used in magnetic loop coupled hearing aids. Alternatively, you might consider looking at am diode receiver circuits that use an OOK decoder. This has the advantage of automatically adapting to the fall in the demodulated amplitude, allowing even millivolt signals to be decoded.

[@toffeeflavour]

Here's an idea, connect the transmit coil to the TX of uart. Connect the smith trigger output to RX of uart on the receiver side. And serial print lots of different data. Cool stuff!

[@miriamramstudio3982]

Really cool project. Thanks

[@QuinceDeMayo-jg5wb]

Brillante trabajo excelente explicación! gracias

[@garethsmith7628]

many years ago I had a radio control book that detailed a similar system, but for the transmit coil it used a loop that ran around the area which you wanted to communicate - eg around the walls of a room, or around an area in a field. you could make the transmit loop as big as you wanted. i belive that then as long as the rx coil was inside the big loop (or up to about quarter to half the tx coil diameter outside the loop) then it would get the signal, so basically like a transformer but with an air core.

[@labiadhchokri2124]

Nice project , you can add a heatsink to the MOSFET. The best component in the project is the variable capacitor.

[@toul100]

his smarts are under rated... you tube gods and developers give this nerd a million followers

[@among-us-99999]

this might be useful for underwater applications

[@AgentOffice]

Excellent work

[@Ozzy3333333]

well done and explained.

[@galaxycomputers7252]

Thanks bro i do same experimemt a year before with new idea power transfer with audio transfer.

[@Scyth3934]

love your videos!

[@sugarart811]

Thank you for your good content, if possible, prepare a project about Lectenna.

[@scootergem]

Useful information, thanks for explaining this so well. KUDOS

[@JayElectroTech]

Thankyou for sharing this greate informational video

[@inventionofelectronicprojects]

Thank you so so much

[@tinkrmind]

Would be very interesting to put the receiver in a faraday cage and compare range vs a regular radio. Lower frequency signals should get higher penetration in a faraday cage.

[@wondercorpse]

Wow your projects are awesome. And it's really cool how you use mostly analog circuits. It's like black magic for us digital dummies:) One small thing: please do something with the background noise. In newer videos it's much better than in the old ones but still the noise puts some pressure on the ears an I think it deters some people. With this quality of the content your channel deserves much more views. Also it would be cool to see some deep dive into schematics that you design, for example component choises and more detailed explanation of the little details (maybe as a separate videos or text posts). So anyway big thanks to you for all this work it's really great.

[@arthursgarage6550]

Analog circuits feel genuinely impossible at times, but they are so satisfying to pull off.

[@SuleimanShuaibu-qf4kb]

good engineer❤🎉good guy that is how the great start

[@JakeHarris0]

The output impedance of a filter should be as near as possible to the impedance of the antenna. The impedance of an antenna depends on frequency and your loop should have a very low impedance (maybe 4.7nanoOhm). The output impedance of your amplifier is also going to be extremely low unless you specifically designed it to have a higher impedance (which you did not). You will be better off just removing those two 1.2kOhm resistors. If you were using transmission lines of some sort between those components, you would need to match to them, but in this case, it is not necessary.

[@Gunbudder]

There is an old defcon talk where a super high power RFID scanner was demonstrated using almost the exact same system you have here. they built it into a backpack with a beefy battery for power source, and it was reading cards from over 35 feet away. a ground station can read cards even farther, with the rumor being that the US/Canadian border has readers that grab your info from over 100 feet away as you pull up to the crossing. Thankfully the banks caught up to RFID security problems eventually instead of continuing to pretend like RFID was bulletproof. most systems that use prox cards for access control require a pin or some other secondary method now. I remember my university had a single code that every student used to open every door back in 2007...

[@ahmetmutlu348]

probably cascaded transistors will do good job at amplifying signals.and may be amplified high woltage coil as transmitter ;) ie something like high voltage high amps pulses

[@AnhProductDesign]

Hi. Love your videos! Just curious where did you acquire electrical engineering knowledge from?

[@robertmonroe9728]

1:40 caps in henries. Cool

[@jhon614]

What software are you using to design and test/model your circuits?

[@ggimas]

This will work under water at this distance as well, while the common multi MHz over the air RF will not work past a few cm. You can demonstrate this if you have a "body of water" near by (pool, lake ocean etc).

[@aeris-mo]

So cool

[@timothyg967]

Video on rotary transformer please -> for magnetless brushless axial flux motors

[@paulbrouyere1735]

You just have a new subscriber

[@jaredharvey1511]

Can you make a transmission with both e and h fields? AKA double the bandwidth. I understand h field is lossy, but for close range WiFi it seems like it would be useful.

[@rentoneureka510]

your project was good , i love it . please what is the max range in meters

[@Dark_Matter2]

wow awesome bro

[@TheRamblingShepherd]

Would this work to transmit through media that block radio, like water? Could this be used to communicate with an RC submarine, for example?

[@Tr0nism]

69kHz nice!

[@Alexander-kj8ph]

So, next an actual receiver with a mixer I guess? I recommend considering tayloe mixer circuit. Then sampling by ADC and digital filtering. That would be nice signal processing playground

[@JustAnotherAlchemist]

On the receiver side, you may want to try looking into something called a regenerator circuit. Also known as a "regen receiver." The theory is to exploit positive feedback to make your tuning tank (coil and capacitor) extra sensitive. Basically, you "tickle" the receiver tank circuit just up to the point where it starts resonating, then cut it back down again and repeat this process over and over while observing the results. The key insight is that it will be easier/quicker to get the tank to resonate if there is an external signal "helping" it resonate. Or, said using the analogy, it's being tickled from both sides. Regen receivers have fallen out of vouge today, but back in the days of vacuum tube radio they were like what LoRa is today. Signal quality (bandwidth) suffered, but strength was greatly increased.

[@Xurikyo]

Love the build, but with that music you're missing a few Kerbals!

[@rezwanzakaria1754]

Hello, Can I use a HF inverter module to feed a HF pulse wave directly to the coil instead of the transmitter circuit?

[@DerMarkus1982]

The Arduino UNO (R3) has an 8 MHz CPU clock. With your "nice" signal that means that you have 115.9 clock ticks per signal cycle. The Arduino Runtime eats up a lot of CPU cycles, especially if you use the provided functions, like pulseIn() digitalRead(), digitalWrite() etc. If you want a cleaner/ more finely resolved signal duration/frequency reading ( 14:15 ), you might want to: A) upgrade to something "faster", like a Raspberry Pi Pico (which runs at a 133 MHz clock) - finer resolution in timing your signal. B) operate your trusty UNO in "bare metal" mode, i.e. work directly with the hardware SFRs in code - less CPU wasted with the CPU in compiler framework housekeeping mode.

[@firosiam7786]

The diagram and all things u said after that I completely lost it mayb this Is for good bright electrical backgrounded people to understand and build.

[@jeadielhosein]

Would you be able to use the signal you created in the distance to to retract objects like magnets from that far away ?

[@jort93z]

no.

[@ZReChannel]

_nice_

[@alexcaleal9025]

Hi, I love this video. One question : Could this circuit be used to transmit wireless electricity and light some kind of bulb other than a small led ? For example a small 12V halogen bulb. My doubt arises because it does not work as a continuous wave, but sending ¨pulses¨ or ¨signals¨. Best regards and thank you very much

[@IngieKerr]

That's sortof answered in the video segment about Transformers -> Crappy Transformers -> Awful Transformers at 5:14 :) ... but in short: sadly no. Unless you're simply looking at very close range, as used in induction chargers for phones. Otherwise the losses are too great at these frequencies of electromagnetism over any useful distance. Tesla dedicated much research into this back in the late 1800s, but very little other than "science" came from it. More recent research using microwaves has proven the theory as viable, but unless you _really really_ need to light that bulb wirelessly :), it's not something that's going to be easy, efficient, or arguably even particularly safe for useful power levels. For the various reaseach, applications, and limitations, you want to generally search for the topics of Microwave Power Transmission and/or Wireless Power Transfer methods.

[@toshaxar]

What kind of glue you usually use for plastic parts?

[@robmckennie4203]

Fascinating that instead of filming plugging in the device you would reverse a shot of unplugging it

[@superkidzach]

9:18, nice

[@ytalanwms]

The LC filter capacitor has a value of 3.3 mH?

[@planktonfun1]

frequency is the key

[@ghanilawal6798]

Are you using KiCad to design your circuits?

[@flaplaya]

Say whaaaaaaat? Haha I love it where have you been hiding this is some serious electrical engineering going on.

[@omsingharjit]

Can you do Arduino complex coding ... Than i have a question ...

[@davidbranch1077]

Liked 💯👍

[@H3wastooshort]

it would be interesting to see how far this would work underwater

[@empmachine]

What's up with the capacitors labeled in Henry?

[@TykeMison_]

I'm curious why you chose such a low frequency? The circumference of a loop antenna is equivalent to a fullwave dipole, and thus magloop antennas of a ~30cm diameter should naturally tune for ~270Mhz, not 69Khz. I've seen 7.5cm copper pipe loops used on handheld radios for 450Mhz.

[@AlPha-lv8ok]

This example is not antenna ? Just transformer coupling ?

[@platscho-mat9131]

Really GREAT WORK ❗ But - WHY ❓ Do you need to transfer RC Signals to a submarine?

[@acidbyte4760]

The 200v diode is blocking the 75v diode from doing any work at all. Also the mosfets body diode is mot fast at all. So placing a faster one in parallel does not improve the body diodes opperation and will still close to late. The use of the 200v diode is good to block the fets body diode from conducting. But in this case the 75v diode's cathode has to connect to the 200v diodes anode. Anyway. Fun project.

[@jasonmorgan661]

Solar panel and flashlight works pretty good for sending wireless signals with minimal stuff.

[@HyperspacePirate]

Yeah, at some point i wanted to do that with a laser

[@jasonmorgan661]

@@HyperspacePirate technically the first electrical wireless transmission was a light and a solar cell. They sent morse code. Ingenious right. ???But can we do this with lazers because light is more robust and punctures clouds to some degree. Second can we send data from one computer to another but instead of radio we use light without the fiber optics 😁😁😊😊

[@thibaut5345]

As soon as a magnetic field varies, it becomes an electromagnetic wave. So I'm confused when you say at the beginning that you will transfer information with a magnetic field only

[@arthursgarage6550]

11:14 since it's a current amplifier wouldn't the gain be 96Db because the equation for current gain in decibels is 20Log(AI)

[@luisencarnacioncisnerosara854]

Magnetic fields can go trouhg any material without being stopped at all, only ANOTHER magnetic field exacly the same properties can reppel It.

[@byronwatkins2565]

First, electric and magnetic fields are radiated together at distances above half a wavelength or so. Second, I believe your 2N3906s are drawn upside down -- possibly they are also installed backward making poor amplifiers. Third, the low input impedance of the 2N3904 greatly reduces the quality factor of your loop antenna. It might be worthwhile to put 1 k - 10 k in its emitter. Fourth, the low resistance (600 Ohm) in parallel with your pi filter also destroys its quality factor. Tank circuits have high impedance at resonance and need high impedance in parallel. I would use ~100 k instead of 1.2 k before the filter and the 1 k - 10 k emitter resistance is also recommended for the second stage. The second 1.2 k is then not needed.

[@calvinthedestroyer]

Try using an MRI machine next :)

[@newmonengineering]

Your findings on the coil sizes are in line with my tests. One day I want to put a coil the size of my wall about 8ft circle, and see how far in the room I can transmit power to charge a phone wirelessly. I think it should charge just about anywhere in the room with a coil that large as the transmitter. The receiver needs to be tuned to the correct frequency but it can be a much smaller coil. Have you tried a really large transmitter coil like this? I think it would be a neat experiment. It could in theory be hidden within a wall and provide wireless power anywhere in the room. I found the size of the coil makes more difference than the actual input power. So theoretically one could take a 5watt large coil and get more out of it than a 10w small coil at the same distance. Hope that makes sense.

[@chrishayes5755]

funny I was thinking of putting one behind the drywall hahah

[@conorstewart2214]

You would need to watch it doesn’t interfere with anything, this is only transmitting small amounts of power, but to charge a phone you would need quite a bit more power than is used here.

[@ozanozdemir5515]

Then that transmitter will charge you instead of phone in the room. :)

[@randomblogger2835]

IN4148 for 75V? the last one I measured was closer to 110.

[@dj13579100]

Could you pass usb data using something like this

[@DirtyGingy]

Damn, you could use this to transmit the base line of a dubstep song and watch grandpa breakdance to it

[@falin9557]

what about a long range bidirectional RC Transmitter and receiver? Try to make a rover that can be controlled at long range and be able to send pictures. Something like Perseverance rover

[@PakiNewsNetwork]

Bro, teach us how to amplify rf 433 MHZ transmitter.

[@paranoiia8]

Now you need to plug it to your TV and see if you manage to lose it under the couch as normal TV remote :D

[@yanish00]

Love the videos but probably not the best idea to use a totally wet fan blowing on electronics 😅.

[@arduinoguru7233]

I had this idea for years, I was not able to build it due to lack of experience or even tools to create it.

[@OliverGardens]

Love the science of this, but I still fail to see the practicality with the disadvantages you mentioned. Did you have a particular application in mind where this would make sense?

[@ddegn]

You don't think free unlimited energy is practical? Yes, I'm joking. My guess is this isn't intended to be practical. I think it was just an excuse to play with electronics and teach us about inductive coupling.

[@mikejones-vd3fg]

Dont worry, most everyone fails to see the practicallity of most scientific technologies and those that dont make lots of $$

[@onmyworkbench7000]

One of the first things that I can think of that it can be used for, is controling devices under WATER where RF FEARS to go.

[@buddyguy4723]

There's is a jurassic park quote for this

[@AgentOffice]

No vision for IR and congested or unlicensed RF.

[@global-hellsorosshjt5469]

Magnetic only? Guaranteed that loop is going to radiate RF at 69Khz; not very far since as you say it's a very short antenna for its wavelength. The receiver looks like an ordinary RF-tuned receiver. The air is not a xfmr core. The fact that the pulse is turned on with a short rise time; one would expect the laplace transform would show frequencies all over the place from this turn-on and from the decay. That could explain the noise. My guess is that this signal could be detected for miles with a VLF receiver with a large array cut for that frequency.

[@ytalanwms]

Something wrong with the 2N3906. The emitter is connected to negative. It's a PNP device, and the emitter would normally connect to positive.

[@axontech]

The amplifier stages shown in that receiver are wrong, they cannot work since the respective first transistor has no collector current at all.