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February 23, 2010
Geek, pilot, dad.
about a week ago
SO.. Then if you’re limiting the current based on the difference between the supply and the voltage drop of the LED, if we had (as an easy fictional example) a 3v drop on an LED, and we ran it w/ 2x AA battery at exactly 3v, we would not need ANY resistor? And, extrapolating from that assumption, I could use 12v and run FOUR of these fictional 3v voltage drop LEDs in series with no problem? If that’s the case, can I estimate the battery life based on the current rating of the LED (ie: 20ma, meaning that it would run 100 hours off of the 2 AA batteries with 2000mah each in my example)?
about a month ago
Looking at the instructions / schematic, the “ground” pin is just hooked to the 3rd prong AC ground.. I should be able to ignore that pin then, right? All the low voltage DC side electronics are completely isolated from this anyway, and so this looks pointless to me..?? Am I missing something?
Shouldn’t I just be able to hook up ground and a digital pin from an arduino and work this thing just fine?
News - Friday Product Post: Rock…
about 2 months ago
You know.. I saw the close-up of this board, sitting on that table, and the white table with the holes in it kind of look like a breadboard, which made the actual circuit look REALLY tiny, compared to those “0.1 spaced” holes my brain was seeing.. :-)
about 2 months ago
I agree that cost isn’t a factor for GPS, but depending on the project, battery life and I/O pins might be.. I was really just curious where it got that data, and how accurate it is..
In the video, part of the data that came back through the email was the “Iridium” Lat/Lon Coordinates.. Nick said that was the transmitter coordinates, but when I type those into google maps, it comes up with an address that isn’t Sparkfun’s HQ… I’m wondering if those coordinates are really that of the transmitter, or if it’s the coordinates of the sattelite when it picked up the message, (ie: not directly overhead)?
That seems unlikely, but with the address not coming up the same, and the text of the message saying “Iridium” specifically, I just wanted to clarify..
As a follow-up, IF this device does know where it is, can it be queried for the current Lat/Lon as a GPS, without calling the satelite? Seems it would be useful to be able to exclude an additional GPS from a project if so, but I’d also think that would be a feature worthy of mention in the video..
News - Enginursday: Supplies!
about 2 months ago
OK.. I’m definitely not an “analog electronics” kinda guy (much happier in an arduino ide or even troubleshooting old fashioned 74 series logic) but I was thinking that must be a very special kind of capacitor to store AC.. :-)
In the description of the schematic, you say “AC power from the line is regulated and stored in a large capacitor”… Dont you mean “AC power from the line is RECTIFIED and stored in a large capacitor”? Either that, or I know less about this stuff than I thought I did, which I didn’t think was possible… :-)
about 3 months ago
As a complete newbie to thermocouples, I’m curious about their ability (inability?) to provide absolute temperature readings.. I did some reading on the wiki pages, and although I admit that my eyes glazed over at some of the advanced math, it seems to indicate that the reading you get is a RELATIVE reading between the tip and the rest of the probe. If this is the case, do people typically have a separate thermometer external to their tested object to collect ambient temperature, or do people just assume “room temperature” and just figure it’s close enough?
The two projects I’m interested in right now are building a pool water temperature probe, and a probe to monitor the temperature inside of a smoker grill (not in the meat, just the air in the smoker) Anyone have any hints or best practices on this?
News - Enginursday: Doing Away w…
about 4 months ago
Wow.. that is pretty mature.. Amazing to think that such things have been ported down to be available on something like an Arduino.. If only there were more hours in the day, I could someday hope to play with all of that!! :-) (where is that winning lottery ticket, anyway!!) Thanks for a great explanation, and all the links!
Very cool article.. I can see many arduino apps that would benefit from a structure like this.. One question that I’ll ask here to maybe inspire a more complex example code, but then probably go just read about myself, is how variables are managed between threads? If thread 1 is monitoring a couple sensors and making calculations, are the variables all global in nature, so they can be monitored, acted upon, or adjusted by the other threads?
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