Member Since: May 29, 2007

Country: United States



Born in California, raised in Minneapolis, moved to CO 13 years ago. Wife Becky, daughter Claire, son Ethan, dog Merlin. Trevor is my brother-in-law, but he may not want anyone to know that…


Director of Engineering


SparkFun Electronics, HID (Assa Abloy), Bearcom, Jon Dressel & Associates, Music tech.

Spoken Languages

English, bad English

Programming Languages

C, bad C


I don ’t associate well.


CU Boulder, Front Range CC, Mpls CC, NEI (in MN, called something else now, I think)


RC planes/sailplanes/cars/helicopters, guitar, astronomy, electronics, scifi, paranormal everything, slot cars, big cars



SparkFun Visits Scaled Composites

A Quick Note - We just wanted to let you know that the Shipping Department is slammed! We're still getting same-day guaranteed orders out, but First Class and Economy packages are taking a few days longer than usual. We apologize for any inconvenience and we'll be back on top of things as…

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Pete and Jim's Trip to the MIT Media Lab

Not too long ago (well, a little while now), myself and fellow engineer extraordinaire Jim Lindblom made our annual pilgrimage to the MIT Media Lab. Why do we do this? Well, I've come to know the Media Lab folk as some people with some unusual perspectives on technology and how people work with…

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Another AVC Update

Good day to you all, I hope it finds you suitably conscious and caffeinated. Or if you can at least achieve one of two, we'll call it a good start to the day. Let's start it off with an AVC update, shall we? To begin with, we're going to clarify the prize structure a bit. There are two…

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AVC 2011!!!

My fellow mole people: greetings to you all. So the world has chugged down another Free Day, for better or worse. And as we begin our recovery (hey, it was a ton of work to coordinate that thing), we set our sites on the next big event on the SFE calendar. And what's that? You guessed it, dudes!…

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Solder of the Ages

Salutations SparkFunions (are we going to get sued for that?)! Before I get to the real meat of the post, I'd like to make an announcement. In case all of you aspiring techno-freaks haven't noticed, we've got a new position open in the engineering department. Two, in fact. So are you…

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Parts, and Parts of Parts: The Untold Story

Working at SparkFun has been a pretty wild ride. I mean, I worked out of a bedroom, with shipping in the laundry room. Wait, that was production in the basement. I remember stenciling on the dryer once. I still can't believe my wife let me do this. My actual responsibilities have shifted…

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Sketching in Hardware 2010

Sketching in Hardware is an annual event where you'll find some real heavyweights in open source hardware, along with educators representing some of the most remarkably high-ranking schools in the world. Presented by Mike Kuniavsky of ThingM fame, the event is three days of presentations of, and…

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Beyond the Calculator Watch

Another Maker Fair has come and gone. This was actually my first time to see it, and oh, what a show! Way more than any one person could effectively take in. I think I talked to a zillion people, both at the booth and walking around, and came back with more ideas that I could act upon. Thus begins…

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Antimov Competition

When BattleBots and mechanical cage matches went mainstream some years ago, I was into it. I mean, yeah, what's not to like? No-holds-barred mechanical destruction? I'm all over that action! Chainsaws, clubs, drills... you could get your fix of medieval siege warfare, mechanical…

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Launching our products!

Anything you can strap to a rocket pretty much takes priority around here, which is to say that if someone is launching a rocket out back, everybody is coming out to see it. Sadly, such tests are few and far between. But if I had my way, every last product would have a ?rocket test? before getting…

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Series and Parallel Circuits

August 20th, 2013

An introduction into series and parallel circuits.
  • News - New Tutorials To Get Your… | last week

    Aw, man. You’re killing me, even if it is true. I’ll most likely return to it at some point soon, but my attention is needed elsewhere for the moment.

  • News - Fluke Responds to Tradema… | about a month ago

    Yes, we’re looking at carrying a Fluke meter, currently leaning towards the 117. But I ask these guys to go and pick their fave and I get a list a mile long of Fluke stuff that they want. “Oh! Oh! Oh! That! Daddy, get me that!!”

    Anyway, it’ll be a few weeks before we have anything to sell, I expect. But yes, we’ll be carrying some Fluke gear.

  • News - Fluke, we love you but yo… | about a month ago

    I won’t lie to you - we were looking at sourcing a 115, 117 or 177. I’ve got a 117 here and a 187 at home. I love them. But this is just the sort of thing that makes you want to stand up and do something. I dunno. I’m just bummed about it.

  • Product BOB-09816 | about a month ago

    Sorry for the late reply. Do I know of any? No. I’ve got some ideas for how to make one, but every user would have to calibrate the thing for their own purposes. Maybe that’s OK, though? We try so hard o make things simple, and I’m not sure I can simplify this one without adding a uC and somehow self-referencing the circuit. Otherwise you’d need a tritmpot on each reference to each stage. And that’s fine for people that know what they’re doing, but difficult to make easy for noobs. Maye we’ll try, though.

  • Product BOB-09816 | about 2 months ago

    Remember that anything you have on the input will get amplified by 100 by the time it gets to the output. More importantly, it’s deviation from the reference voltage of 2.5V that’s getting amplified. For example, if your input is 2.4VDC, the output at the first stage will be the 2.5V reference minus (inverting amplifier) 10x(2.5-2.4), or 1.5VDC, and the output of the second stage will be 2.5V plus (inverts again) 10x(2.5-1.5), or 12.5V. Which it can’t do because the supply voltage isn’t that high, so it’s railed (hard up against the supply voltage).

    Amplifying DC is tricky. Any offset that you haven’t planned for is going to jack you up. It can be calibrated out, but maybe that board isn’t what you need. Hmm… Interesting product idea, though.

  • Product BOB-09816 | about 2 months ago

    Correct on C5. C6 is bottom right, which is the one that’s attached to the tap on the pot.

  • Product BOB-09816 | about 2 months ago

    It’s primarily designed for AC. But if you jump across C5 and C6 with a little bit of solder and turn the pot all the way up, it should give you something approximating meaningful at the output. My only concern would be the tolerances of the reference resistors (R8, R3, R9 and R6) and how that will propagate to the output. But if you’re willing to calibrate it even loosely, I’d say you have a better than average chance of success.

  • Product BOB-09816 | about 3 months ago

    Yeah, then turn the pot all the way up. That should work. But I foresee you having offset problems, so you might have to adjust one or both of the reference dividers (R3 and R8, R6 and R9) to get an output in the linear region.

  • Product BOB-09816 | about 3 months ago

    You can definitely use it for audio, and you may not need to cascade two of these boards for any distortion. The board has 2 stages that run a gain of 10 each, so voltage gain is 100 when the trim pot is turned all the way up. Also there’s no regulator on the board, so you need to run it at a voltage that’s compliant with the LMV358 (2.7V-5V). Lastly, if you want to drive a speaker directly, you need to put a cap between the output of the board and your speaker, otherwise you’re going to run a DC current through your speaker. No good. There’s already a cap on the input, so you don’t need to worry about DC there.

  • Product WRL-00152 | about 3 months ago

    Yes, possible. But honestly, your success will come down to the code that you write.

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