Circuit design challenge/contest - Page 1
Forum section: electronics / general

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 21, 2016, 07:58:29 am
content: This is an idea which we've had over onDF, and which went fairly well but it's a small community so we only played a few rounds. With the wide mix of beginners to experts here, this could even be a regular thing I think.Anyway, the idea is:Design a circuit to the specifications provided.Challenges would be held, say, biweekly or monthly. The specification would be random, chosen by a judge or panel (suggestions welcome). Players have some time to design, build and test their submissions.After submission is closed, a panel judges the entries (for correctness and repeatability: entries which can't be built from the info submitted are disqualified), and judges or forum viewers vote on the winner.Prizes provided by donation from anyone who feels the need: viewers, participants, judges.Submission classes/bonuses might include: simplest/most complex (e.g. by number of components), precision (just barely within spec, most precise..?), abuse of the rules/specs*, stuff like that.(*Taking a hint from the IOCCC**, abuse of rules will be accepted for the given challenge, but will probably lead to changed rules in the future. Debug the challenge AND win a prize!)(**Which if you aren't familiar, is theInternational Obfuscated C Code Contest, which features some quite bizarre and interesting programming examples, indeed.)Sound like a neat idea?Example challenges:Oscillator: open class. Circuit has to create a reasonably periodic signal (bandwidth < 10% of center frequency; fundamental and harmonics dominant). Signal level must be measurable (say, >0.1V into a reasonable load: 10x probe, 1M scope input, 50 ohm terminator, etc.) at the output.Function Generator: triangle and square wave outputs, variable frequency. Judged on straightness of square and triangle wave sides, duty cycle (closest to 50%), rise time (as a fraction of the average operating frequency), range of frequency adjustment (within a single range if switchable).Pulse Generator: fastest risetime wins. Repetition rate >100 Hz, pulse width >10ns, rise time as short as possible! (Likely, you won't have an oscilloscope capable of measuring your entry's true rise time; some judges will likely have equipment capable of measuring them, which shows how important it is to be able to accurately describe your design!)Being an analog type, I would of course prefer all manner of analog circuits, but the principle applies perfectly well to all hardware. Digital examples include counters (clock, frequency counter, PLL magic, etc.).I would suggest that digital logic ICs up to LSI be acceptable, but programmable devices (CPLDs, FPGAs, MCUs, etc.) be off the list. Why? Because then it's just another programming challenge, and there are plenty of those around. And if you're going to allow one programmable device, why not another? You might as well allow a PC running an emulator for <device>. Which breaks the rule of having a physically reproducible copy around. Which is another practical reason: probably no judges have the devkits, programmers and toolchains for all programmable devices.) RAM/ROM is debatable; I respect, say, making your own state machine, but having a huge number of states available puts many analog circuits at a huge disadvantage. Some rules might be selected on a per-challenge basis.Tim

author: iampoor
author_rank: Frequent Contributor
timestamp: March 21, 2016, 08:22:34 am
content: I would be interested. Being a beginner, this would be a great way to get design experience without having to set the constraints myself. Sometimes (ahem...always) that gets in the way of actually desiging circuits.

author: krivx
author_rank: Frequent Contributor
timestamp: March 21, 2016, 08:44:33 am
content: Sounds interesting.

author: tszaboo
author_rank: Super Contributor
timestamp: March 21, 2016, 08:52:37 am
content: This sounds like what I'm usually getting paid for, and at least I dont have competition.Jokes aside, it is a good idea. Circuit ideas are worth from nothing to gold bars, so seeing a lot of them is a good thing.

author: peter.mitchell
author_rank: Super Contributor
timestamp: March 21, 2016, 09:26:16 am
content: I am posting to indicate my interest.

author: krivx
author_rank: Frequent Contributor
timestamp: March 21, 2016, 09:39:27 am
content: Quote from: T3sl4co1l on March 21, 2016, 07:58:29 amDespite the name DF appears to be mostly English language. Thanks Tim, there goes this week's productivity

author: deephaven
author_rank: Frequent Contributor
timestamp: March 21, 2016, 09:57:17 am
content: That sounds like an excellent idea. I think it would be good to have some designs which aren't too stringent other than 'it works' targeted at beginners. So often there are forum messages from beginners which ask "What shall I make?", and this could be a source of ideas for them.

author: LordNobady
author_rank: Contributor
timestamp: March 21, 2016, 10:06:12 am
content: I like this idee.I do think that Programmable components can be useful for some challenges.

author: tggzzz
author_rank: Super Contributor
timestamp: March 21, 2016, 08:26:21 pm
content: Who owns the IP in designs submitted?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 21, 2016, 10:18:07 pm
content: Quote from: tggzzz on March 21, 2016, 08:26:21 pmThat would be consistent with the forum, which I believe is, users retain ownership of content.Not that you'd expect to ever make a cent off of, like... discrete 555s and stuff.Tim

author: Mr.B
author_rank: Unknown
timestamp: March 22, 2016, 12:00:16 am
content: I would not be skilled enough to compete, but am eager to learn from the vast knowledge base here.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 22, 2016, 04:24:47 am
content: Quote from: tggzzz on March 21, 2016, 08:26:21 pmProbably,in most cases,National Semiconductors,their heirs & successors!

author: Mr.B
author_rank: Unknown
timestamp: March 22, 2016, 08:06:12 am
content: Tim;Would you be prepared to be the adjudicator of rules submitted by contributors to this thread?I would love to see this concept develop.Humble hobbyists like myself will learn much from the expertise here...

author: TinkerFan
author_rank: Regular Contributor
timestamp: March 23, 2016, 09:34:20 pm
content: Although I'm a beginner as well, I would be interested, just to see the different outcomes. I think a hell of a lot could be learned by looking at the different circuits (and by asking questions about it).

author: richard.cs
author_rank: Super Contributor
timestamp: March 23, 2016, 11:30:46 pm
content: Sounds fun to me

author: lapm
author_rank: Frequent Contributor
timestamp: March 24, 2016, 07:32:11 pm
content: Might be fun

author: stmdude
author_rank: Frequent Contributor
timestamp: March 24, 2016, 08:40:18 pm
content: Sounds like a lot of fun. Probably could get a guy or two from work to join in on the fun as well.I _suck_ at analog design though, so some digital stuff would be nice to see.

author: grouchobyte
author_rank: Regular Contributor
timestamp: March 26, 2016, 01:38:36 am
content: I vote for a a pulse generator. I think I can improve on this one.Variable width .....seconds if you want w/ 415 ps Tr (10-90%). Min pw ~ 1nswill drive 4.5 volts into 50 ohmsno avalanche transistor (sorry, JimW... RIP)simple off the shelf componentsDid it already for a client in the US. I own the rights to it. No theft of IP involved.Here is a screen shot. It was measured with a 20db, 50 ohm attenuator into a Tek S2 sample head.

author: tggzzz
author_rank: Super Contributor
timestamp: March 26, 2016, 07:33:43 am
content: Quote from: grouchobyte on March 26, 2016, 01:38:36 amCould you show a picture of the risetime (as opposed to an impulse response), please. I suggest a 10ns wide pulse would be sufficient.What's the bandwidth and risetime of the scope you were using?

author: grouchobyte
author_rank: Regular Contributor
timestamp: March 26, 2016, 09:18:51 am
content: Quote from: tggzzz on March 26, 2016, 07:33:43 amSorry, up all night with shoulder pain after breaking it in a fall. Right now I am sitting in a chair and keeping myself sane by entertaining myself and others on the blog. I should be in bed with my wife, actually.Okay, here's an old image from my dropbox folder, circa 2008. Gotta dig out the hardware, perhaps when I am better to provide fresh proof of this.This pic is at 7ns. Sorry, this gonna have to do for now. There is zero overshoot and zero undershoot. This is a 4 volt pulse into 50 ohms.Without terminating into 50 ohms it gets bigger and way uglier, obviously.....signal integrity 101The bandwidth of the sampling system used to take this measurement is 10 Ghz. When I am better, I will measure it with my MSOX3104, 1 Ghz Agilent scope. It really is 415 ps symetrical Tr/TfAny more questions? Can it wait for the contest? Please dont ask me for a schematic or hint, or how I did it. FYI it wasn't hard to design, it just took a little out of the box thinking, thats all.@grouchobyte

author: tggzzz
author_rank: Super Contributor
timestamp: March 26, 2016, 09:45:43 am
content: Quote from: grouchobyte on March 26, 2016, 09:18:51 amThanks for the much more definitive and useful picture. The device would be useful when fettling with scopes' front ends.Nasty - the fall, not the pulse! When I snapped my patellar tendon, the person in the next bed was in pain having broken his shoulder blade while demonstrating to his kids how he used to swing on a long rope over a big sandpit. When I bumped into him a few weeks later he was much improved. (FWIW, I also snapped my achilles tendon showing my daughter how to use a springboard safely. The irony is entrenched in family lore)I built a generator based on three 74LVC1G*-plus-resistor in parallel. I only have a Tek 485, so I canseea risetime of <1ns - not bad for a 40 year old 350MHz scopeIndirect measurements lead me to believe the risetime is actually around 625ps.

author: grouchobyte
author_rank: Regular Contributor
timestamp: March 26, 2016, 10:38:02 am
content: Quote from: tggzzz on March 26, 2016, 09:45:43 amTek 485 is still a great scope, for a crusty old analog box. i think I still have mine in the attic. A close friend of mine designed the character generator for it. Paralleing 74s or other logic is a great way to get super nice Dv/Dt edge rates. However driving 4 or 5 volts into 50 ohms, with clean results presents some unique challenges. Besides yourself, who here in this thread has got the analog chops to beat me on a killer pulse generator challenge?BTW: is there a prize or reward? Do I get a lucky star and an honorable mention, some status or Thor snacks?

author: tggzzz
author_rank: Super Contributor
timestamp: March 26, 2016, 11:05:03 am
content: Quote from: grouchobyte on March 26, 2016, 10:38:02 amWell, you can see the risetime at the bottom of:https://entertaininghacks.wordpress.com/2015/08/11/measuring-digital-signal-edge-rates-without-an-oscilloscope/That's a 2.5V signal, not 5V signal, but that doesn't matter for my purposes.BTW, the 485 doesn't have onscreen characters - that came in the next decadeQuoteWith all prizes (and with many other unsocial sites), the thing to look at is whether submission of an entry affects your IPR.

author: grouchobyte
author_rank: Regular Contributor
timestamp: March 26, 2016, 11:30:47 am
content: BTW, the 485 doesn't have onscreen characters - that came in the next decadeCorrect. However it did exist late in its generation but you still couldn't obtain one.....except for those very few "unofficial" units.

author: tggzzz
author_rank: Super Contributor
timestamp: March 26, 2016, 11:34:28 am
content: Quote from: grouchobyte on March 26, 2016, 11:30:47 amIn which case I put on my solipsist hat - and still say 485s didn't have onscreen characters

author: joeqsmith
author_rank: Super Contributor
timestamp: March 26, 2016, 03:01:14 pm
content: Quote from: T3sl4co1l on March 21, 2016, 07:58:29 amAnything that gets people involved with learning is a good thing. As the value of the prize goes up, the rules will need to be very clear. Seems like a lot of work to put a contest together. Some of the mags I used to subscribe to would have contests from time to time. To get paid, they may do a promotion of a say some new device. The company who makes or distributes the device sponsors the contest. You may have different categories like open class (anything goes, no cost limit) to some specific task.We did play with some home made oscillators a while back:https://www.eevblog.com/forum/projects/el-cheapo-oscillator/25/https://www.eevblog.com/forum/projects/waveforms-in-a-74ls04-ring-oscillator/25/Even something as simple as an oscillator, there are a lot of metrics to consider. Cost, highest BW, lowest distortion, lowest TC..... Tighten it too much, you take the fun out of it.

author: Pack34
author_rank: Frequent Contributor
timestamp: March 30, 2016, 12:51:07 pm
content: I like this idea. It could be good fodder for Dave's YouTube channel. Prizes could be simple stuff like a monthly uCurrent, shirt, or even some of the mail-bag like flair that people send in for him to show off on the blog (widget they just started selling, kickstarter promo, etc.).Monthly could be fundamental novelty circuits in the spirit of open source. Pulse generators, audio amplifiers, discrete versions of common chips (i.e. 555), etc. Maybe an open-ended yearly contest of a larger system.Just throwing out thoughts.