Pete's back! Last month's episode on buck regulators and home LED lighting was a hit, so this time around Pete is continuing the discussion with an explanation of boost regulators. As a bonus, you get to watch Pete's Yoda coffee cup magically relocate itself around the desk throughout the video.

Leave any questions in the comments, and we'll have another According to Pete for you next month!


Comments 19 comments

  • He's a witch! Burn him!

  • Hey Pete, thank you for continuing with these videos and keep them coming. For me as a hobbyist, I like how you make it so easy to understand the fundamentals of each circuit. Like the other dude below somewhere, I wouldn't mind some quick verbiage on the "Poor Man's RF Loop".

    Cheers.

  • Great video and explanation, Pete! However, I was hoping for something about what was done to improve the acoustics for the "New Product Friday" videos. ;-) Maybe sometime in the future on that?

    I'd also like a brief explanation of the "boost/buck" regulators that can operate in both modes to control a much wider input variation. And you might say a word or two more about the "poor man's RF loop", for those who aren't aware of how to set it up.

    And one final thing: DigiKey.com has LOTS of inductors (their product selector is claiming well over 100,000, though that often includes both ones that are not "in stock" but are still in production as well as separate listings for different packaging for the same part, e.g., in a bag versus on a reel). I'm sure that Mouser.com has a huge number as well, and probably Jameco, though I haven't checked the last two sources. So, even if we can no longer get them at SparkFun, we can still get them.

  • liked it! thanks!

  • Is there a way/purpose of combining a Buck/Boost circuit for the ultimate power supply?

    • That would be a sepic. http://en.wikipedia.org/wiki/Single-ended_primary-inductor_converter

  • Enjoy your video tutorials - keep them coming! BTW, you said "That's really good, that's better than a linear regulator" (at time code 9:11) How does a linear regulator boost the output voltage? Perhaps your head was still in BUCK regulator thinking?

    • I think I was referring to the efficiency in general... wasn't I? Maybe I'm nuts.

      • Yeah i also thought that that comment didnt make much sense, because there isnt a linear regulator setup to compare against, because boost... (also, if you have low enough voltage drop you can beat 77% with a linear regulator...)

  • As always, awesome video.

    Super glad you touched on the efficiency aspect. There are so many people in industry who look at a PMIC that says "Up to 96% efficiency" and then assume you'll get that regardless.

  • Pete, great section and I like to play with coils also. It is too bad that you don't have much in the way of coils on the site. I also like the poor mans RF loop. I used it to check the RF field on a Joule Thief I built. I hope you keep up video tutorials on the unusual. Things like your presentations make this site worth more than just a reference site.

  • Pete, if you are planning to make show something "FCC may not be happy about" - such as a wireless microphone - do mention the rules, please. Especially in Europe building stuff that transmits in bands like the FM radio band is pretty much verboten unless very strict power limits are followed and hefty fines are possible. I believe the US rules are more lenient, but you have also overseas viewers/customers.

    • The scale of anything I may be thinking of is something like 2 feet. At this point I just wanna see if I can inject audio onto an emitter of a Colpitts osc config and somehow get some AM out of it. Pretty low-tech and small scale, but I'll say something about the rules if it gets to that point.

      • The problem is that even that could run afoul of the rules - some bozo will connect a longer wire as an antenna to it and it is over the 50nW ERP that is allowed here in Europe. And you can certainly exceed 50nW even with a single transistor running from a battery, no problem at all. At least we have got the 50nW now, it used to be completely verboten before - so no FM band "bugs" or streaming music to an old car radio for us.

        If people want to experiment with radio transmission, it is better to get a HAM radio license. Even using the ISM bands may not be legal, because the equipment is not certified (obviously, when it is homebrew).

        You aren't very likely to get caught unless e.g. neighbours complain of interference or you cause interference to some important equipment (e.g. airport, emergency services, etc.), but if you do get caught, the fines are very stiff and there may be even criminal prosecution. I don't think it is worth having a criminal record because of a stupid learning experiment.

        Teaching people to flout the rules is just wrong. At least make them aware of the restrictions - you cannot prevent people from being stupid but you can make them not be ignorant.

      • Or modulate the voltage supply to your RF carrier oscillator. Not pretty but you'll get an AM signal out! An early AM transmitter, built by Reginald Fessenden at the dawn of the last century, did it with an ordinary carbon microphone (taken from a telephone handset) in series with an AC signal (from a generator at 50KHz). Scary stuff. Did I mention the microphone was water cooled? Don't try this at home...

        • Use an LM317 adjustable voltage regulator to modulate the supply voltage of your oscillator to make an AM transmitter... When you realize the LM317 is just trying to keep it's output 1.25V above the 'ref' terminal, you can use it for all sorts of things it wasn't originally intended for... - Steve

        • Ha! Very cool. There's got to be a dozen ways to generate am "wrong but good enough". Maybe I'll play with that tonight...?

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