As a retired Electrical Engineer with 45 years of experience, I must say that I admire your procedures! You are absolutely correct to document faliures, that's how we learn!

I absolutely love the way you put googly eyes on everything. never stop.

Here are a couple of tips from Deuteron Technologies Ltd, Jerusalem Israel. First, you can get at least an order of magnitude higher magnetic field if you close the magnetic circuit with a laminated iron or ferrite core. Secondly, use a lock-in amplifier, or equivalent to look for your signal. In other words you should process the signal by continuously multiplying it by a number proportional to the applied current, and then use a low-pass filter to extract the flow signal. It's easy to see nanovolts of signal that way. Your biphasic waveform is good, but better if that was the current waveform, not the voltage waveform, so you should make a controllable current source rather than applying a voltage directly to a coil. This becomes much more important as you increase the inductance of the coils and you increase the frequency.

Rotate the pipe into a vertical orientation. This ensures the pipe is full of liquid. This is a practice used in industry when installing mag flow meters.

the issue here may not be electronic. it might be more practical. your pipe setup allows for air in the pipe. this will show up as noise. raise the discharge so the pipe stays full. long straight runs get a more laminar flow which reduces noise (10*diameter at least before meter). also make sure your bucket is full so pump does not vortex and suck air. I troubleshoot these occasionally, air in pipe is one of the most common issues.

Man, I love this channel. Some of the highest quality content on KZfaq!

It is definitely important to document well researched failures. Extra kudos for this and all your hard work man, love the channel.

Dear +Practical Engineering, Please use the "math" function on your 'scope to multiply channels A and B, where A is the uV signal from the electrodes and the B is the current through the field-coils. Next, "measure" the average (mean) of the product-signal (i.e. the output of the 'math' channel), normalize for the excitation-amplitude and voila, you have filtered the needle out of the haystack :) The DC (average) level that you measure should be proportional to your flow. You can even measure bidirectional flow. For best results, put channels A and B on AC-coupling, HF-reject, heck you can even do triggered averaging if you trigger off of the current (channel B)! This is my favorite version of a low-budget-synchronous-detector :)

I really love this video, really shows how electrical engineering and engineering in general is riddled with difficulties and some times failure opposed to just the façade of perfection some people imagine.

I really like the fact you still shared the results even with failed practical part. Failure IS an option, if you have data as a result.

4:35 "we would say signal to noise ratio is high" could be corrected. Thank you for the video!

The quality of these videos is crazy. I like how you pour your heart into these projects. I'm living with my parents still so i can't exactly do these kinds of experiments and understand hands on but these videos really help a budding engineer see what engineering is like in the real world. Keep the videos coming!

Thank you, we are currently doing an engineering school project with a homemade magnetic flow meter, and we couldn't figure out why we ended up with so much noise on our signal. But you resumed everything ! Thank you very much.

Yes man, documenting failures and errors in a neat and descriptive manner is by any mean not less important as documenting a success! Thank you!

"Artisan electro-magnets hand wound with locally-sourced magnet wire" is what got the thumbs up. That's gold, Jerry, GOLD!

When you "spin your wheels" it helps connect the dots for me as well as it "spins" off answers to problems i cant quite grasp a way to answer the issue. This is why i am completely enjoying your channel. The parallels of how to and why are shown in a way where i can apply the therory and have found solutions through the things you explain in the method you ecplain them. I cannot thank you enough for "spinning your wheels" especially on a roof top. That one long tube from your roof top solved 4 issues that i couldnt find a way to figure out what the root cause for. Please dont stop. You keep my wheels spinning to find the answers to the issues i encounter. Thank you.

Good video, glad it got posted. This is a super-tough problem and a much better showing than I would have made. I like the demonstration of how to solve the problem.

The most significant advances I've made in life have often stemmed directly from initial failures. Your frank and refreshing embrace of this notion is admirable. Tellingly, your unsuccessful first attempt has led directly (through the comments as well as your own self-reflection, I should think) to the basis for a new experiment that will undoubtedly improve upon version 1.0, as well as the broader enlightenment of your audience. Kudos!

Thanks for the videos. I tried to be an electrical engineer but i didn't realize how important trig identities are. Your videos allow me to live vicariously through an engineer.

Such an underrated channel, the quality of these videos is phenomenal

I thank you for showing the challenges we face when doing testing and research. Nothing is ever cut and dry simple testing or building.

I'm definitely happy you made this video. I never really thought about how flow meters work, though it seems so obvious that it's not a trivial problem once you get that initial thought. I really enjoyed the video!

Best demonstration which i have ever seen

What a trip down memory lane, in the early 80's I used to work for a company that made mag meters. Thanks.

I love the point you made about documenting failure. We don't get nearly enough of that in STEM education.

The logic you used to eliminate the noise issue is the same logic we use when tuning controllers. You do a step change and measure the change in the process to tune a controller. Really cool video, thanks for the video.

Love how you are always on the edge on your comfort-zone!

Outstanding job explaining the theory and practice, along with the challenges you encountered. Very useful material.

You engineers are absolute wizards..!

Always wondered how digital flow meters work, even without refinement you effectively demonstrated both theory and practice.

The production quality on these videos are going up every time great work keep it up and you will blow up!!!

@4:35 -- the signal to noise ratio would be low. The noise to signal ratio would be high.

If I ever get my hands on an oscilloscope, I'm totally putting googly eyes on it too.

Nice Video, but a small error 4:33 the SNR is low not high, no worries hope no one got confuesd

You sir have my thumbs up for documenting your failure. It is probably the most underrated and unappreciated part of research. Hell, all failures are frowned upon. No doubt, anyone new to the field has to tread the path of same failures (may not be all, but some? definitely!) due the lack of their documentation, leading to wastage of time and funds

Having implemented many magnetic flow meters, two of the main issues to consider when installing the meter is to make sure there is no air in the line near the meter (maintain a full pipe at all times). If possible install the meter vertically, but if not, make sure it's not in the highest place in the piping or anywhere else where air might accumulate. Looking at your testing fixture I would assume that there is air going past the meter. I would have put some kind of trap in the end of the line before running the pipe back to the bucket. The other factor is to install in a place so many pipe diameters upstream and downstream to avoid turbulence and try for laminar flow. That part of the test rig looks ok to me.

No worries about the fails. I always wondered how these meters worked and thanks to your informative video... I now do. Thanks for a super channel!

top men are working on these artisan magnets

Every time I watch your video, I learn something new. Thanks for being with us.

You are exceptionally genius person. And there is a need of such teachers or mentor in our society. Respect for u sir

Thank you for making these, I've watched about 5 of your videos today and you've got such a friendly, welcoming demeanour! Keep going buddy, I'm sure your subscribers will keep climbing. Oh and greetings from a Scottish graduate Civil engineer.

You want the SNR to be as big as possible so you have to do to things: Increase the signal: Easiest way would probably be to increase the windings on the coil and/or the voltage you're feeding them. This increases the magnetic field and therefore the induced voltage. You could also try to switch to a fluid that is less conducting than water. Decrease the noise: Use shielding! You basically built an antenna! I would shield the set-up with a non-magnetic material like aluminium foil. You also have to use coaxial cables to the electrode in order to decrease fields feed into the cables. Hope this helps.

Thank you for the interesting and well made videos. I love how your channel shows the process that leads to a solution as well as the knowledge that is used on the way.

i love how you covered the rigol and specs on the scope yet on the screen it says rigol at plain sight

Another great video! Really enjoyed it!

I've been interested in this before, Really glad to see it explained so well. thank you!

I've worked 10 years as a fracker and we use 3" and 4" mag meeters in some of our rate monitoring. It's neat to see the theory on how some of the stuff around you works Shame you couldn't get it to work, but interesting concept

Great demo despite the less-than-usable result. ! I'm glad to see you used only artisan hand-wound coils from locally-sourced wire.

Great video. And thank you for sharing your "failures" too. I know I learn more from mine than from the successes!

Your videos are awesome buddy I tried engineering for 3 years before switching to business but I think I want to get back into it

Another great video. Congrats on the sponsorship! I like the music you used for your into and outtro. You should keep using it!

Amazing video! I worked with some magnetic flow meters once and was really curious to know how they work!!!

Fantastic video, and even better explanations! Impressive visuals you did there as well.

Great video and very thought provoking for someone like myself who has been working with electronics all my (Relatively long) life. I was too lazy to go through all 500 comments, particularly on a 2-year-old video, however here are a couple thoughts... First off, without an iron/ferrite core in your coils it’s going to seriously limit the amount of signal you get out of it, a core helps to localize and focus the field, which is why you’ll see so many coils with cores regardless of whether they’re generating or trying to receive fields, aside from very high frequency, low inductance coils. Second, you might want to check into isolated, high gain amplifiers used in EKG machines or those that try and pick up muscle currents via EMG (electromyography). Ideally you want a high-gain, differential, isolated circuit because that way you can avoid inadvertently coupling in external electrical currents that may end up causing random offsets in your signal. I would steer away from an off the shelf h-bridge simply because you are using something that was never intended for a clean, spike-free output of exactly the same signals every time, there’s just no point in its normal application. Using an op-amp with a split supply set up to produce a square wave output would probably be a better bet. And finally, you might want to look at a high-resolution ADC (I.e. at least 14 bits effective/noise free, not the resolution of the ADC itself since they are always going to have a higher resolution that’s impossible to get in practice due to design limitations) to sample your signal and try and get a little more resolution from such low-amplitude signals vs your 8-bit scope. A better ADC isn’t mandatory assuming you can get enough gain from your main amplifier, though obviously this is all a matter of trying to squeeze more signal out without it vanishing into the noise.

Thank you for this video! It was very interesting to watch. And the visualisation of information is really great.

Would love to see a redesign video of this. Success videos make failure videos all the more relevant.

Awesome video! Many concepts here. Not a failure at all.

Practical (real) Engineering is just like that. Best luck next time! Love your videos!

Definitely carry on and go into details :) I love this!

Applause 👏 great video!

Enlighting. Keep them vids coming.

Your the man, great experiment.

Really great video and informative. Keep 'em coming!

I enjoy your videos. I would recommend driving the magnet coils at a frequency that is not harmonically related to the line frequency or other interference sources. Amplify your sensor signal and feed it to an analog to digital convertor (ADC) at a sampling frequency that is a much higher harmonic of your driving source. When amplifying the signal, amplify it just enough to keep it close to the full scale input of your ADC without clipping. Then take a discrete Fourier transform (DFT) of your sampled signal to filter out everything except the frequency of your driving source. That will have the effect of having a very narrow bandpass filter of your sampled signal and greatly reduce the effects of noise. I've used that technique to pull signals out of the noise in other projects. It done right, you can increase the effective number of bits of your ADC by an order of magnitude or more. Main issue I could see is keeping your driving source from radiating into your sensors directly -- so layout is probably critical.

Enjoyed your video - learned a lot!

You're right : Showing it even if its a fail is great !

Grady, you are amazing.

Shameful or not I am liking this video for the effort involved and explaining the concept elegantly.

Very good video! Even though your demo didn't quite work, your explanation of the theory was very good!

You "failure" saved me from spending a ton of time trying to DIY this myself, so thanks! I should just spend the money and buy an off the shelf one.

Love this channel!

You are awesome. I watch you videos and learn many things. pls continue doing reasearch on it. I know you can do it. thanks for sharing this hard earned knowledge to all for free.

Thanks for posting this! Great video, even if you didn't get the result you wanted!

Nice work. Thank you!

Trying to measure the flow of liquid as been living hell at work lately. We've tried turbine meters, ultra sonic meters, Coriolis meters, and now we're trying a torus wedge differential pressure meter.

Noise to signal is high, not signal to noise.

You should make a video with Destin (SmarterEveryDay)!

I love that you put googly eyes on EVERYTHING.

Excellent video!

Great videos! Great presentation and graphics too ! Well done!

That intro sounded like a PBS or NPR show. But, it's good to see you getting the recognition from the people with money that you're worth supporting.

lovely insights thanks.

I work at a power plant in Sweden and i'm in awe. It's not the simplest solution but if it works with both low and high flows then i can see it being used in a number of applications. Exampel, dosing were it can be tricky due to the low flow rate to measure the flow. BOSS! COME CHECK THIS OUT!

Pal, I like your humble approach to science. Keep it up

I liked the video after just 2 minutes. Great video and a nice channel. Good job man and have a nice day.

Cool video. this reminded me of a company near where I live that makes flow meters which "listen" to the pipe in order to determine flow rate.

Dude, you're awesome!

I love this channel !

@1:10 - "...and the challenges that arise when the real world doesn't quite match the theory". Brah, welcome to Electrical Engineering 101! The most precise imprecise engineering major of them all haha. In all seriousness, love the videos! EE here with a closeted passion for ME and civil engineering stuff. Keep it up!

Amazing video!

Awesome, man!

the video is technically amazing :O thank you so much

Love your work.. Your a genius! Keep it up..

This brings back memory’s of my MIT days. The hours spent making artisan coils for electromagnets.

Fantastic, thank you.

A combination between positive displacement and induction coils is quite easy to do. I've seen industrial flowmeters with simple design as such. It is using an orifice plate, a rotating wheel with an iron core attached inside a pipe, and a coil to induce flux. The amount of voltage induced would translate to the velocity of flow. It is essentially a small hydro turbine and the orifice plate serves as a constant.

Great video Gready. I didn't know that application of electromagnets. I love the way your cat chills at the end of the video xD.

Many thanks for your effort and explanation very good video God bless you I am learning from you.

another fantastic video don't worry about failure no one's perfect. keep it up

a very good demo. I would suggest looking at op-amps