Blog - Screaming Circuits


10th Anniversary Top 10 Traps

A few folks requested my presentation from out 10th anniversary open house.So, without much adieu, here it is.

Download Top 10 traps 7-2013 (PowerPoint format)

Download Top 10 traps 7-2013 (PDF format)

Duane Benson
10 times 10 isn't necessarily equal to 10 times 10.
Especially if you mix bases.

Super Small Via In Pad

Via in pad is an old issue that still pops up now and then. Our standard answer hasn't changed: No open vias in pads. But one of the questions we get related to the subject is: "What if we make the vias really small?"

Beagleboard U6 viasLogically, that makes sense. In fact, in some cases, the via is so small that it's essentially closed. If it's so small that it really is closed, then it's not an open via. But look close - if it's closed with solder, that solder may melt during reflow leading to an open via.

The images here show some pretty small vias. I believe they're 0.3 mm in diameter.

Beagleboard vias back sideIn the first picture, on the left, it appears that the vias are open. They aren't though. This board (an unstuffed Beagleboard) uses soldermask on the back side of the PCB to close off the vias, as shown in the image on the right.

Our recommended method (se more detail here and here) is to plug the via with copper or epoxy and have it plated over at the board fab house. Next, we'd recommend via caps on the component side. FInally, capping the back side with soldermask, like this example can work, but it comes with the risk of voids. The via caps and also pop open, leading to an open via.

Duane Benson
No more open vias-in-pad, I mean it!
Anybody want a peanit?

CAD Data Files

I've spent a fair amount of time researching and writing about the centroid file and about CAD library footprints. One of the challenges in this industry is that somethings that are "standard" really aren't all that standard. That's why we emphasize following IPC guidelines when creating library components.

Well, a few things have changed since we started doing this a decade ago. For one, some of the enhanced manufacturing file formats (as opposed to the 1970's vintage Gerber format) have become more prevelent. Those new formats are a very good thing.

Most CAD packages can now output either ASCII formatted CAD data or ODB++ format data. Those file formats have all of the data that would otherwise be found in the centroid and Gerber files. They also have more accurate data. If you can get one of those formats out, go ahead and send it to us. We can also take plain old Eagle CAD .brd files. If in doubt send one of these newer files along with the centroid and Gerbers. We'll use the file with the best data and, we may be able to simplify the file preparation Centroid snippet rot optyou have to do with future jobs.

And speaking of the Centroid, don't worry so much about the rotation column in the Centroid file. You can consider rotation to be optional now. You don't need to check the rotation, nor do you need to remove it.

Duane Benson
Who will win? Godzilla or Centroid? Maybe the Smog Monster?

 

10 Years of Speedy Prototypes

10th anniversary badgeSN74LS90 years and we're having a party - a party for engineers. Good food & drink, factory tours, door prizes, presentations... You just need to RSVP to: rsvp@screamingcircuits.com or call us at 503-266-9100

July 18, 2013, 3:00pm to 7:00pm.
1140 NW 3rd Avenue, Canby, Oregon 97013

See all the details here.

10 Years of Screaming at Circuits

ladies and gentlemen and engineers of all ages...

Screaming Circuits, A Milwaukee Electronics company, is celebrating ten years of specializing in speedy prototype assembly.In honor of your great support, we're having a party! Come and see where it all happens. Take a tour. Enjoy a come-when-you-can buffet, beer, wine and SMT parts. We promise that the food and drink will all be lead-free.

See more details here:

blog.screamingcircuits.com/10-years-of-screaming-at-circuits.html

July 18, 2013, 3:00pm to 7:00pm. 1140 NW 3rd Avenue, Canby, Oregon 97013

Just RSVP to: rsvp@screamingcircuits.com or call us at 503-266-9100.
  • Food to eat. It will be delicious, but we can't promise it will be nutritious.
  • Wine and beer from Canby's own St Josef's Winery
  • Fabulous door prizes
  • A Google Nexus 7 32GB Wi-Fi tablet for one lucky winner**
  • A $2,500 assembly coupon for another lucky winner**
  • A nice little gift pack from Screaming Circuits for everybody
  • Tables with people to answer any questions about any part of what we do for you
  • Informative presentations***
  • A few examples of fun projects we build for people
  • The "Game room" where you can challenge a Screaming Circuits champion to pool or ping pong

Duane Benson
Come on in and see what's happening
Pay the price*, get your tickets* for the show

* The price is free. just send an email to "rsvp@screamingcircuits.com" and you don't really need tickets.
** We consider you all to be winners, but only one of you will with the tablet.
*** This is supposed to be fun and informative. Sales pitches have been banned from the event.

Push-me Pull-you LEDs

I may never get tired of talking about LED and diode polarities. It's so much fun. Not long ago, I wrote about two LEDs from the same manufacturer, marked with opposite polarities. I recently ran into another one, but at least this one tells you on the same datasheet. This image is an actual unmodified clip from the datasheet.

LED confusing polarityI can't for the life of me understand why this would be done on purpose. I could maybe understand if one was designed in a different building, but it couldn't have been too hard for someone to say: "Hey - wait a minute..." before sending these things off to manufacturing.

Of course, maybe they built a million before noticing and then just decided it would be easier to change the datasheet. Regardless, it's kind of nuts in my opinion.

The other thing here is that, while you can generally get away with the indicators "+/-" on an LED, you can't with all diodes. Thin Zener and TVS.

Duane Benson
Matter + antimatter makes what?
Does it really matter?
Does anybody really know what time it is?

Intergalactic Geek Pride Day Quiz

There was a time when "Geek" was far from a badge of honor. Jr. High School (AKA middle school) was developed specifically for the purpose of making geeks miserable. We were told that lockers were  designed for holding books, lunches jackets, but in reality, the secret anti-geek coalition had lockers installed so geeks could be stuffed inside of them, or could have the doors slammed in their faces.

But, then something happened. While the world wasn't looking, a geek became the richest man in the world. Pro-nerd and pro-geek movies became popular. It became cool to claim to be a geek or a nerd. The problem is that there's a big difference between claiming the title "geek" and being given the title "geek."

Well, May 25th is Geek Pride Day. In honor of Intergalactic Geek Pride Day, I've put together a little quiz on the subject.

Questions:

  1. Is it better to be considered a nerd, a geek or both?
  2. What's the difference between a nerd and a geek?
  3. Does the outside world know the difference between "nerd" and "geek" and thus does it matter which one you're called?
  4. If you've never actually been called a geek, but claim to be a geek anyway, are you really a geek?
  5. If a geek talks in the woods, but there's no one there to hear, did the geek actually speak?
  6. If you can explain what you do for a living (or hobby) to a random stranger and have more than about one in fifty understand, can you still claim to be a geek?
  7. If you don't have enough cables laying around the houses to connect just about any two pieces of computer / electronic equipment together, can you really claim to be a geek?
  8. If you can't assemble a spare PC from parts you have around the house in about an hour, can you still claim to be a geek?
  9. If you can't count in more than one base, can you still claim to be a geek?
  10. If you don't love songs by Tom Lehrer, can you still call yourself a geek? (If you don't know who he is, quick: Youtube)

 Bonus question:

  1.  Tesla or Edison?

Answers:

If you're a true geek, you already know the answers so I don't need to list them.

Duane Benson
The best revenge is not violence or deviousness
The best revenge is to be happier
...and to build robots for world domination

 

How To Exercise an Element of Control

Control yourself

Canada's Singing Astronaut

If you're going to exit, you may as well exit in style and I can't think of a better example than Commander Chris Hadfield's "good by" from the International Space Station on Monday (May 13). Thank you, Astronaut Hadfield.

Since this is my  electronics blog, I've got to tie it into electronics design and assembly, so, like um... If you're building electronics for space, you might need to better insulate your PCB traces or put wider gaps in because otherwise you might get arcs and stuff. And be sure to shave your tin whiskers.

Duane Benson
Please sir. May I have some more

Unsolicited

I have a question for you. When is the last time that you responded to an unsolicited email? It's been a very long time for me. However, I just did open up and read an unsolicited email that actually seems somewhat relevant to me. The specific subject was an offer to be a guest blogger here on blog.screamingcircuits.com. I don't know that I'll take them up on the offer. It kind of depends on what they might want to write about.

But I did jump over to their website: www.circuitspecialists.com. I've never done business with them, but they do have some interesting products and they started in a garage in 1971. Anyone who started in a garage 40+ years ago and is still around must be doing something right. Their site looks like it's more or less focused on test & measurement, prototyping, robotics and other things electronic. (I think I've heard the term "prototyping" someplace...).

What first caught my eye as relevant was their section on digital panel meters. Why would that catch my eye, you might ask? (Or you might not) The first panel meter I looked at is an "independent power supply version." Ah, the plot thickens. Just last weekend, I exploded a power supply in a robot I'm building. It didn't actually explode, but it certainly did release smoke and stopped releasing electrons at about the same time. Smoke for electrons is not  a fair trade as far as I'm concerned.

I was putting a digital Ammeter on the main power line and couldn't remember if it the meter was designed for high side or low side. Poof! I empirically determined that it was designed for low side. I should have known better because it drew power from the robot power supply without any isolation.

If my meter had an isolated or independent power supply, then I could probably have put it on the high side. Oh well. It wasn't the first time I've traded smoke for electrons, nor will it likely be the last.

Duane Benson
rhythm characterized by regular recurrence of a systematic arrangement of basic patterns in larger figures