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Member Since: August 17, 2010

Country: United States

  • Sure, I agree it definitely can be done with a microcontroller's on-board ADC and I suppose "all that bad" is subjective. But, to do it right requires a properly designed anti-aliasing filter and accurate voltage reference. Surely everyone who is going to use this with their Arduino understands these analog design issues and properly accounts for them right? Just like SparkFun did in the tutorial, right? Sorry about the sarcasm there but, without an anti-aliasing filter and true voltage reference you have no idea how accurate the reading will be.

    Your basic Arduino setup is using it's own power supply as a voltage reference for the ADC right? How accurate is that, five percent, ten percent? How much noise does it have, how much does it vary under load? In contrast, the INA219 has an internal high accuracy referencer and proper filtering built in, is listed as 0.5% max over the specified temperature range, and provides both current and voltage measurements with this accuracy.

    As for the number of pins used, the INA169 requires one ADC pin for current and a second if you need voltage measurement as well. So, one or two per channel. The INA219 requires zero additional pins if you already have any other I2C peripherals or two pins if not. Each additional channel requires zero additional pins up to 16 channels when you run out of unique addresses.

    The INA169 is a perfectly fine chip when properly implemented but how many people who attempt to use this product will truly understand and address all these issues. The INA219 takes care of all the messy analog details for them and will be far more accurate for your average user.

    As for whether there is enough interest I cannot say. For me though, the digital output high-side current sensor is something that is worth it at two or three time its cost. To get that kind of accuracy with a microcontroller's on-board ADC is not trivial and I would not even consider attempting it for other than general order of magnitude type measurements. One can easily find a breakout board with an INA219 available online for only slightly more than this one so it just puzzled me, with something so much better already available why SparkFun would design this product around this chip.

  • I am curious why this was designed around the INA169 instead of the INA219? The INA219 has an internal ADC and an I2C output that provides the current and voltage values directly. The INA219 makes dealing with current measurements in a microcontroller project very easy. The common mode range on the INA219 is a bit lower at 26 volts but this is fine for the majority of applications I would think. INA219 based breakout boards already exist from other suppliers but it would be preferable to be able to get them from Sparkfun.

  • I used a 1/2-20 die to "adjust" the threads and now they screw in to the base just as easily as the two that come with the kit. After threading the die on the whole way I turned it over and threaded the pipe in to the back side of the die to fully cut the threads right up next to the hex.

  • Well, if you're looking for unconventional tips... When I had several large boards with lots of components I wanted to salvage I used a related method. This was for through hole components though not surface mount parts.

    Fist I took off all the special or valuable parts I wanted individually by hand. After that everything else left on the board isn't worth the time to remove one by one. So I clamped the board upside-down and then used a propane torch in one hand and a shop air blow gun in the other hand. Keep the torch moving or you will catch the board on fire. Once you have all the solder in a few square inch area molten pull the torch back and quickly blast straight down on the holes with the air. It should be obvious that this method should probably not be used inside your house! Wear proper PPE and do it somewhere the molten solder spray won't hurt anything.

    The yield rate for this method isn't a hundred percent; some parts will be melted beyond use and some will be stubbornly stuck to the board. However, if you have lots of boards that you are going to pitch anyway it's a quick way to salvage a lot of components.

    Obviously, this is not following any temp profile and could be stressful for certain types of components so use common sense on what you reuse. I wouldn't use it on ICs but probably for resistors, capacitors, LEDs, switches, connectors, etc. I think it is a useful method when the parts would otherwise not be worth the time and effort to remove.


  • I suppose the "Display Filter" part of the title should have been better emphasized in the description to help reduce confusion. Still though, using the words "Graphic Equalizer" first in the title and then starting the data sheet description with "The seven band graphic equalizer IC" is misleading.

  • It is not completely your fault since the manufacture's data sheet calls it such but, this is NOT and equalizer. It provides no ability to alter the frequency domain characteristics of the signal, it does no equalization. See http://en.wikipedia.org/wiki/Equalization
    This would probably be more correctly described as an audio frequency spectrum analyzer.
    I was a bit confused when I first read the description because I could not figure out if this actually provided some type of adjustable equalization or just spectral analysis for display. After reading that data sheet it is the latter. It is a neat chip but it is not an equalizer.

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