Member Since: October 17, 2012

Country: United States

  • I know the mosquitoes are big around here, but WHAT IS THAT?

  • Quick question related to something on the PureEngineering website. (Maybe they can comment here.) I see a picture of it plugged into a UNO, pulling power from the ARef pin. Is that really in spec for the AVR chip to provide power on that pin?

  • That’s what I suspected. I missed the zero reference adjustment, but I only scanned the documentation. Good to know that one can program a zero reference in the sensor instead of having to calculate it in the application for every reading. (Loading a known constant at each power up is a trivial function for boot up).

    The main reason for the zero reference question would be to figure out the best place for a center of rotation for a circular scanner. (Or even a scan-line type scanner to “map” a surface.)

  • Nice demo by Nick. I know he was wearing the “black out” glasses, but I wonder if he actually did the demo with his eyes closed anyway. I probably would have to allow me to concentrated on just the sound. He states “hypothesis confirmed”, but what did he think of the experiment? Was it cool, freaky, difficult, all three, what?

    One thing that bothered me about Robert’s presentation… I know the clam knife isn’t sharp, but having any knife sitting on a desk with the edge up makes me nervous.

  • But if one LED fails as an open (like from over-aggressive cleaning to get that dried on blob of food off a LED), wouldn’t the entire strip go out? The old Christmas tree string problem?

    Not a problem, per se, but a design quirk. ;-)

  • This is one of many cases of where “common usage” and “technical accuracy” are at complete loggerheads. Many people call a AA cell a battery… :-/

    Technical accuracy states that a single cell (terminated or not) is just a single cell. In order to be a battery there needs to be multiple cells connected together.

    But, common usage states that both individual cells and batteries of cells are all called “batteries”.

  • Actually, the datasheet that I looked at specified a range of 20m for the LED/Pin model with optics. The Laser/Pin model is (as you said) 60m. The data sheet doesn’t have a configuration for a range limited at 40m…

    One thing that I’m not sure about (either the datasheet, Operating Manual, and Tech Brief don’t mention or I didn’t notice when reading all three) is where is the 0 reference for the measurement? The PIN diode or the front of the optics?

  • As did I. I used a 12V power brick, and then a 12V DC rocker switch to a 12V LED strip. All temporarily tacked up so I can remove it easily and with little evidence when I leave this rental. All the wiring that is exposed under the cabinet is 12VDC, not wall AC for safety.

    The downside of my implementation as far as energy conservation is the power brick is always on, I only switch the 12VDC.

  • Well, aluminum won’t rust. As far as splash proofing/resisting for ease of cleaning up, Pete didn’t show anything.

  • From a mathematical point, the “rule of thumb” sounds reasonable. The circumference (and thus effective trace width) of the hole will be 3.14159… times the diameter, but since we have inside plating, it will be a little less. So 3X sounds good.

    Actually, the effective trace width of the hole would be slightly larger than 3.14… times the diameter. Because the designed hole size is the desired finished hole size. When the board is manufactured it will be actually drilled with a slightly larger drill and then plated down to the designed hole size. But rounding down to 3 times the diameter adds in a little safety margin slop. Also a via may not self cool itself because it’s a constrained space, especially if the vias are tented so no convective air flow currents can be established. I don’t have the experience to know how much to derate a tented via for current capacity. I just can conceptually realize that it is an issue.

    A couple advantages for multiple vias on a single power trace vs. a single large via on same said power trace: * If all vias are the same size, that keeps the drill size count down. Some board manufacturers start charging for ridiculous numbers of drill sizes, and others will “change” your design and optimize drill sizes and all of the sudden one of your THT parts won’t fit (or won’t draw solder down the hole around the pin) because the board house made the poor decision to use a smaller drill to save setup time. * Even though the probability of a trace with many vias getting a single cracked plate-through barrel is higher than a trace with just one via, your design will be less adversely impacted by that single cracked barrel.