Screaming Circuits: August 2013


Pads on Ground Plane

Pour-no thermalGenerally, small pads for passive parts are connected  with a single PCB trace of equal size to each pad. That's the right way to do it.

However, sometimes, circumstances dictate a little different approach. The illustration on the upper right here shows something of a worst-case. This is for a snubber (resistor, capacitor pair) between two power planes.

A couple of things will likely happen. The power plane will act as a heat sink, preventing the solder paste on one side from melting, resulting in a poor connection. Or, the unequal melting could lead to surface tension pulling the part up, causing tombstoning.

Pour-with thermalMost designers are aware of that, but sometimes, thermals will be deliberately turned off to allow for better current capacity to and from the large power Mosfets (not shown). If that's the case, make sure that you can turn the thermals (see image on loer right) on or off by the part, rather than just by the plane.

Duane Benson
The rain falls mostly on the ground plane due to static attraction

Geek Week on Youtube

In case you haven't heard, it's Geek Week on Youtube. In honor of that, here are the top ten most incredible pieces of trivia from ancient Geek Mythology. You can scroll down and read them here, or have the questions read to you, by me, over on our Youtube channel. 

 

First question:

F: Everyone has heard the trite phrase: “There are 10 types of people; those who understand binary and those who don’t.” Who’s missing?

E: All your _____ are belong to us. Fill in the blank.

D: Who, in the late ‘70s correctly predicted that by the turn of the century, it would be possible to use our computers to find the answer to any question?

C: And, what name did he give his computer?

 B: Bell is reputed to have said: “Watson, come here. I need you.” What was Charlie Klien’s equivalent statement in 1969?

A: Who caused the “Y2K” problem? And, no, that’s not it. You’re already wrong.

9: Who did business under the name “Traf-O-Data”, starting in 1971?

8: One particular semi-nautically named person wrote the first word processor for the Apple II while in prison. Who was that?

7: And, what was that word processor? Bonus points if you’ve actually used it.

6: Who, in 1995, while on his deathbed, claimed to be DB Cooper? Bonus points if you know why I might know this.

5: How many tubes did a standard superhetrodyne radio have?

4: Name them.

3: When did the first man go into space? Be advised that you’re probably wrong.

2: When someone refers to “scout water”, what are they referring to?

1:  How many instructions did the first CPU have?

Now, drum roll please… ,

0: What is the least known, yet probably the most significant law that enabled the personal computer revolution to happen?

And... This is a contest. The first five people, in North America, to get the correct answers will receive a T-Shirt from us - or the five closest to complete and correct. You have until next Monday (8-12-13), when we post the answers. If you choose to submit answers, send them to dbenson @ screamingcircuits . com with the subject line "Trivia answers"

Duane Benson
According the The Buggles, video killed the radio star
If so, then why do we still have radio telescopes? 

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