Fulgorian Harp: [2] Guitar Sustainer Coil Physics 

Thanks for making this!

Hey great video Michael!! I went down a rabbithole of ebow schematics last year and made a little PCB based on the Vegas Cycling Freak video, I really wish these videos were out when I was working on it! I also used the mini buzzer coils and ran into the problem where the coils have to be so close to the string that it starts buzzing. Thanks for all the info (and great graphics) in these videos, I'll have to try another iteration of that project!

I forgot to mention that if you measure out 8 Ohms of wire and it only fills your bobbin half way, then you can go up 2 sizes AWG (eg from 30 AWG to 28 AWG) and 8 Ohms of that will fill your bobbin exactly.

Yeah, defo wasted talents going on here, it's quite refreshing that's someone in today's world with all the distractions that have most people from exploring possibilities of "things" is caught up with their own interest and hasn't lost the critical thinking aspect that perhaps educational bodies seem to want to take away from students, just leaving answers in their heads that will never be challenged by the student (I've a video in the making that actually mentions this inability to explore in a less than a 10-second clip! from some kind of brain analyst that teaches things about the brain to students). I think you are a dying breed, Michael, a valuable soul. I always love your enthusiasm and passion with your content, it's a little sad that there are not far more subscribers that are electrically minded following you, there do seem to be quite a few people out there on RU-vid that enjoy electronics, but they don't seem to go into as much detail, and for me this detail I find very interesting, not that I comprehend some of it, but it demonstrates how you are using your brain! Great content as usual.

When doing those inductor filling calculations, I ditch the “proportionality” and use the proper constants. Not only does the bobbin have a maximum cross section for wire, but also a maximum power dissipation. For a guitar pickup maybe that’s 5W. Then knowing my voltage, I figure out what total resistance I’ll need to meet for that power consumption, and calculate the number of turns and of what diameter to meet that based off the cross sectional area of windings I have to work with. Then I design a driving stage, in this case it can be any old half-bridge, be it with FETs, a monolithic L293/L298, or a BJT totem pole. Gotta include the voltage dropout in the above calculations though. Does having a permanent magnet in the output coil actually matter? It’s necessary in the input coil since you need it to induce a magnetic field in the string to detect its motion, but here you’re already producing a magnetic field with the output coil.

I've seen videos of folks making pick-ups, and it seems they have special machines that rotate/wind the bobbins, so yea, lots of winding. I mean, you could DIY a simple bobbin-turning device. Thanks, good solid stuff here!

Dude, you should be a professor... Also, we should hang out. I guess it's probably my turn to visit you this time. Just crossed the 1-year mark at my new job, so I'm now accruing paid vacation at twice the original rate. Hopefully that will mean more road trips in my future!

I appreciate your explaining of the electronic circuits! And I like the passion! You seem really fun! And clever, the robot on your channel page looks very advanced. Then, your "RU-vid Clickbait" faces start appearing. :-( I've heard it still increases views, even though the person looks really dumb on the thumbnails. Well. It scares me away :'-D

That's probably more analysis than some guitar pickup manufacturers do to build their pickups. One more thing to add to the pickup side is that there is some sort of an upper limit or at least it goes with the law of diminishing returns: The more turns an the thinner the wire, the higher the impedance of the coil. Then you start needing higher and higher input impedance for the amplifier. I quess the practical coil size and the thinnest wire that's possible to coil by hand will limit it before in this application. In guitar pickups when you start increasing the turns you increase the inductance. That means the amps input loading down the pickup will affect higher frequencies (harmonics) more and the sound will be darker. In the sustainer type thing it might not be that big of the deal as you only need the fundamental or perhaps a few lowest harmonics. Anyway... You probably have this figured out by now, but hey... Let's hope this counts as engagement to the youtube algorithm. :)

I wonder, could you take an old DC motor (old drill or something) apart for the coiled bobbin?

You don't need a magnet for the output coil, having an iron core will help, but no magnet is neccesary because the coil is an electromagnet in itself.

What's the name of the software shown on the left at 3:00?