Congratulations To Our Op-Amp Challenge Winners!

The real world is analog, and the op-amp is the indispensable building block of many analog circuits. We wanted to give you analog fanatics out there a chance to shine and to encourage our digital brothers and sisters to dip their toes in the murky waters where ones and zeroes define the ends of a spectrum rather than representing the only choice. Hence, we presented the Op Amp Challenge. And you did not disappoint!

We received 83 entries, and it was extraordinarily hard to pick the winners. But since we had three $150 DigiKey shopping sprees to give away, our six judges buckled down and picked their favorites. Whether or not you’ve got the Golden Rules of the ideal op-amp tattooed on your arm, you’ll enjoy looking through all of the projects here. But without further ado…

The Winners

[Craig]’s Op Art is an X-Y voltage generator to plug into an oscilloscope and make classic Lissajous and other spirograph-like images, and it’s all done in analog. Maybe it was his incredible documentation, the nice use of a classic three-op-amp tunable oscillator, or the pun hidden in the title. Whatever the case, it wowed our judges and picked up a deserved place in the top three.

Hearkening back to the pre-digital dinosaur days, [Rainer Glaschick]’s Flexible Analog Computer is a modular analog computer prototyping system on a breadboard backplane. Since you have to re-wire up an analog computer for your particular, it’s great that [Rainer] gave us a bunch of examples on his website as well, including a lunar lander and classic Lorenz attractor demos.

And there was no way that [Chris]’s interactive analog LED wave array wouldn’t place in the top three. It’s a huge 2D analog simulation that runs entirely on op-amps, sensing when your hand moves across any part of its surface and radiating waves out from there. You have to admire the massive scale here, and you simply must check out the video of it in action. Glorious!

Honorable Mentions

We wanted to give you plenty of room to strut your stuff, whether that was making something classic, something entirely off the wall, or something that would fit on the measurement bench at the metrology department. So here’s a quick rundown of just some of the projects that we thought were worth a look.

Hyper Precise

[Mark Omo]’s LOCKDOWN is a superb lock-in amplifier design and a great demo and explanation of how one works. Essentially, if the signal you want to measure has a periodic component – sits on a carrier wave – then you can use a lock-in amplifier to “tune in” on just the signal, and the non-periodic noise drops right out. This is an amazing build and a shoo-in for the hyper-precise mention. Plus, what a snazzy circuit board!

[Floydfish]’s ultra-low noise amplifier “Take a ‘NAP’ and enjoy a moment of silence” is a classic design, but as is always the case with precision builds, a lot depends on the details of how you do it. Here, a copper-clad cage with Mu-metal shielding is put inside a nicely labeled cookie tin to get the job done. The design pushes the chosen precision op-amp to its limits.


[MaBe42]’s circuit sculpture Chaotic Lighthouse struck a chord with our judges, bringing Sprott’s chaos circuit into duty to drive a bunch of LEDs. Make sure you check out the video.

Until reading up on [Bruce Land]’s Model nonlinear biochem reactions using opamps, we had no idea what a repressilator was. And honestly, we’re still not sure. But [Bruce] made a purpose-built analog computer to simulate this ring of genes that suppress each other’s expression. Whoah.

And [Jarrett Cigainero]’s ADS-B on a real RADAR CRT only uses a little bit of op-amp to go from the DACs to the screen, but we just love the sweet phosphor glow, so we’re going with it.

The Classics

One of the absolute classic op-amp applications is simple signal level scaling, and [David]’s ultra-low-cost pH amplifier circuit for 3.3V MCUs is a great example. [Florian Dirnberger]’s nice Triangle-wave oscillator gets the job done and is very well documented. [555TechLab] implemented a classic 0 V – 10 V variable voltage reference with one of the only 741 builds in the whole contest. And if all this op-amp stuff makes you want to know how they work under the hood, check out [Mitsuru Yamada]’s CMOS Homemade Operational Amplifier for a non-traditional take.

Amazing Analog

We haven’t run an analog design contest in years, and we’re guessing that there was a lot of pent-up demand, and we were really floored by the number and quality of entries here. Be sure to check out the big list of contest entries because we’re certain you’ll find something else that strikes your particular funny bone. Don’t get me started on the audio effects, for instance!

Congratulations to everyone who entered, especially those who took home a prize. And as always, thanks to DigiKey for sponsoring.

15 thoughts on “Congratulations To Our Op-Amp Challenge Winners!

        1. Oh, but that isn’t a bodge wire!
          It is a bundle of carbon nanotubes transporting fribbits to the tumblurfanon for quasistatic expansion!

  1. First of all: a lot of great projects! Congrats to all the creatives!
    Second: It would be great if HaD could link the results into the original announcement page.

    But what surprised me: Reading the announcement I had expected that the three winners would be one in each of the three categories listed. But which of these three winners (which are all great – no question) falls under the category “hyper-precise”?

    Could the editors/jury please comment?

    1. The three winners are picked overall. The honorable mention categories are “just for fun” and/or for inspiration.

      Usually we have anywhere between three and five honorable mention categories — I suppose there’s less confusion when it’s five than when it’s three. Sorry about that!

          1. That’s actually my point, ideas are certainly worth “noting” as you say, and there were several novel ideas that were well implemented. OTOH, implementations of textbook circuits are a dime a dozen and can be completed in an evening or two.

  2. Its a pity Mark Omo should name his project after the most damaging and disastrous policy over-reaction of this century, but the dot io page for it definitely is an excellent resource on amplification under tricky circumstances. Good to see a clear explanation of lock-in amplifiers than can actually be followed, and which doesn’t depend on a single “do it all for you” chip.

  3. The Lockdown lock-in Amp: how about modulating a LASER diode pointer, and demodulating the light reflected back through a telescope and a photodiode? Shouldn’t it be able to demodulate the faint voices and noises inside? The modulating frequency should be high. BTW, what are the frequency specifications?

  4. >ADS-B on a real RADAR CRT only uses a little bit of op-amp to go from the DACs to the screen, but we just love the sweet phosphor glow, so we’re going with it.

    Um, I used OpAmps for both of the switching power supplies, not just for the analog input from the DACs.

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