According to Pete - July Edition #1


Quick addition to today's post - just want to let everyone know SparkFun will be closed on July 4th (Wednesday) in recognition of Independence Day. We'll resume normal operations on the 5th!

Today is the first Monday of the month (goodbye June!), and that means we have the first monthly installment of "According to Pete." Today, Pete is talking about inductors - from the very basics to the, well, not-so-basic. Check it out:


Vimeo version can be found here.

If you have any comments (nice shirt!) or questions for Pete, feel free to leave them in the comments section below and we'll do our best to answer them. Look for the next installment of ATP in mid-July. Cheers!


Comments 39 comments

  • Oh, man. 26 minutes? Sorry everybody. That’s too long. I really thought I could do it in less time. And I didn’t even cover inductive reactance or resonance (either self or with a cap)…

    • Pete, when you talk inductors, you really talk about electromagnetism, which cannot be covered in any amount of time.

      Bravo for doing a great job on providing enough info that people are not as in the dark as they once were.

    • Wow, that was awesome! You should have kept going. When you’re in the groove, don’t stop!

    • Pete -Great Job, You could have gone on for four minutes more and I would have been just as happy to listen.

      The one thing you didn’t point out yet: Your torrid transformer runs a lot cooler than the old stand-by Laminated Core Transformers. (Part of that has to do with Eddy’s currents. But I guess you will get around to that later… Also Pete- I can’t remember the name of the company but there is one that makes Torrid Transformers for Audiophiles up in Canada to whatever specification you need. Years ago I had them make up one that was dual 25W 12V output for one of my projects. My project could not take the heat of a Laminated Core Transformer- at least I didn’t need to fry an egg on it.)

      • I think it’s eddy currents. They are magnetically-induced currents in the core. I’ve also seen them in aluminum (yes, aluminum) tubing where a bar magnet is dropped through it and is slowed down due the magnetic field generated by eddy currents.

      • I think you mean Plitron toroidal transformers- a torrid transformer would still be very hot, and muggy too.

  • Nice shirt!

  • Master, prithee do tell of these inductor-capacitor black magicks. I sense that immense power doth lie therein.

  • I can’t believe that no one has commented on the web page changes. So far, I like it! Also, Pete, nice job. I always enjoy your videos.

  • I’d really like to see that pickup coil in action! I’d love to building one, too!

    • I have a confession to make. I made that thing to pick up EVP’s, assuming they’re real. I sent it off to a guy named Jeff Ritzman. I’m not sure if he ever got anything out of it or not. But maybe this should be one of the projects I offer up?

      • Yeah, that might be interesting. Even if it doesn’t work in the way you intended, it’d still be fun to pick up non-paranormal electronic voices.

  • LOL Nice 4th o July link!

  • Ferris materials? Like wheels, seats, carnies? ;-) Oh, I guess you meant ferrOUS materials. Kidding aside, another great AtP. Clear explanations on a semi-mysterious subject. Great job Pete!

  • So this was a great lesson. How about for your next project you build on the inductor a bit and we build an inductive charging station for a robot ;)

  • I want to hear more about that pickup you built.

  • Awesome episode.. I like the project episodes, but refreshers in the basics is MUCH easier to get something out of rather than trying to find something in YOUR project that might be applicable to what I am doing… I had a basic understanding of transformers in a power supply function, but now I know a lot more about the fundamentals involved, and why stuff happens/works.. If you do a followup (200 level course!) on this subject, you might want to talk about the DC isolation that you get when using a transformer (ie: no common ground) and how/why that might be good or bad..

  • I know :D a Tube amp Project :D

  • Dude, you teach this stuff better than any profs I’ve had in Electrical Engineerings.

  • Thanks everybody for chiming in. Between my quick blaze through a subject and all the comments picking up where I left off, I think people can really learn something here.

  • Thank you for doing this segment. I used inductors in my last project and even looked into their purpose a little, but didn’t really get it. I thought perhaps they had a little magic in them. Now I know that the magic is really magnetism.

  • Pete, The word you are looking for in the Amorphous ferromagnetic material. Usually they are heat treated and crystallized to attain a µ in the range of 20K-100K. The toroid is wound using a metal tape with an epoxy insulating layer between the winds to minimize eddy current losses. Great video, inductors are a lot of fun.

  • Nice presentation! I’d love to see a followup on the fun, but dangerous, applications of inductors (maybe a field trip to the Tesla museum in CoSpgs? and an explanation of wireless charging?). On the other hand, this might be better left to the anonymous youtube posts.

    Given the outrageously hot June in Boulder, how about a live demo with suitable “volunteers”, of the duality of voltage/current versus water pressure/flow?

    P.S. Transistor Man rocks, but jumbo paisleys are sweet too.

  • The ‘metal can’ that they put around inductors to shield electronics from magnetic interference is made of ‘Mu metal’ or ‘permalloy’. Both are nickel-iron alloys which reduce magnetic fields inside a closed container made of them.

    Oh, and nice shirt, btw :-)

  • Nate! Your going to make your guys work the week and only give them Wednesday off? I thought you’d be nicer than that and not do what everyone else does. Why can’t just close from Wednesday to Friday? Nothing is going to get done anyway…..

    • Because if we don’t come in on Thursday and Friday, we can’t get all those beautiful red boxes out to you, our loyal customers!

    • Not getting to work one wendsday at Sparkfun is punishment

    • We’d take more time off for the forth of July holiday but there’s too many new products, videos, kit cards, robots, and websites to work on. Too many projects, not enough time…

      • Oh? Is the world coming to an end and I wasn’t notified? Why can’t these things wait till next week? You know Android’s Ice cream sandwich (Yawn) release only has 11% Android user base. So why does everything have to be done NOW NOW NOW?! What are you going to do with all these things that you have to work on? Let me guess… Sell them? Tell me how that isn’t related to money…

        Be cool and be different and give your guys Thursday and Friday off. I’ll bet those guys out in Silicon Valley are doing it. Are you going to let those guys show you up? Seriously? You disappoint me Nate. Mr. AVC isn’t as cool as the guys out in Silicon Valley? Blah! It’s a sad day in Geek World!

  • Why can you assume that µo is 1? I thought it was 4π x 10-7 or 1.257 x 10-6 in free air.

    • Did I jack that up? I’ll have to find the reference that I saw…

      • I think that it might have been the relative permeability that you saw, which is µ/µo = 1.00000037 Wikipedia table

        • Derp. That was it. You’d think I’d remember that stuff.

          • Yes, in fact you should use µ instead of µ0. µ0 is the vacuum permeability and µ=µ0*µr where µr is the relative permeability of the material. µr=1 in the case of air coils that’s probably why you made this mistake.

  • Now I kind of want to get a cap and a coil together so I can throw a party.


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