SparkFun will be closed May 25, 2015 for Memorial Day. Orders placed after 2pm on Friday the 22nd will ship out on Tuesday. Thanks!


Roger K.

Member Since: August 25, 2012

Country: United States


See My GitHub for all of my Arduino and other programming projects (all free GPL3 code)!

  • That “day of the week” algorithm was not devised by Tomohiko Sakamoto in 1993, it was “devised” by a German mathematician Christian Zeller in 1883 see Zeller on Wiki

    Here’s a generic piece of code in C that implements Zeller’s Congruence:

    if (month < 3) { month += 12; year -= 1; }
    if (month > 12) { month -= 12; year += 1; }

    All variables are ints, and the names should be self-explanatory.

  • I see there is a spot on the PCB where an SMA connector can be soldered. Does anyone know if these traces are active (that is, if I solder on an SMA connector, will it work)?


  • Could anyone tell me - is this button a “snap action” type? That is, does it have a “microswitch” type of action that makes a mechanical and tactile “click” when depressed or released, or does it just use ordinary contacts?

  • I also have a driver for this board: GitHub DS3234 Note that this driver does not need to use the Arduino SPI… it can use any pins you wish.

  • Something important to know about this (and other Saleae products) is that they fully support Linux 32 and 64 bit, as well as OSX.

    Obviously a big plus for those of us who use a REAL operating system. :)

  • That’s a packaged Polaroid 6500 ultrasonic range finder (originally invented for Polaroid auto-focus cameras). Polaroid made sensor kits available in the early 1990’s (a kit contained two of the gold foil sensor modules and two PC boards with the analog and digital circuitry). Polaroid no longer makes these modules, but third parties have copied it and currently sell them. If anyone is interested, here’s a link to a PDF datasheet for the Polaroid 6500 module. It’s super easy to use and produces VERY good quality range information. The 6500 is the best ultrasonic sensor I’ve used, by far.


    One important thing to know is that the 6500 boards use a LOT of current (around 2 amperes) for a few milliseconds. Therefore, you need around a 470uF to 1000uF capacitor across the module VCC and GND or else the module will crash your microcontroller.

  • My 11 y.o. daughter is having a blast with these panels! I made her a little UV LED pen which draws very nicely on the panel. I also made a “camera” by taking a 12" cube cardboard box with a 4 inch diameter hole in one side, attaching a 4 inch diameter magnifying glass to the box and placing the photoluminescent panel inside. Cover the lens, take the box outside on a bright sunny day and uncover the lens for about 10 seconds, then run back into the house. It makes an amazingly good quality POSITIVE image (that is, bright is bright - unlike a NEGATIVE). After about 15 minutes, the image fades and another “picture” can be taken. These panels would be, in my opinion, a GREAT present to buy a 5 to 15 year old kid as a stocking stuffer. Buy more than one, so one panel can “fade” while the other is being used.

  • These make an awesome diffuser for RGB LED’s!

  • A three terminal regulator (7805 or LM317) with a resistor between Vout and Adj makes a fine constant current regulator for LED arrays or LED backlights. Of course, it’s linear, so any excess power is dumped as heat… but it’s simple and cheap.

  • Here’s a hint: Use these along with the long male header pins Sparkfun Part Number broken into individual pins and you have a male connection any time you need it!

    To keep the pin in permanently, carefully solder it in. Hold the crimp connector end at the wire strain relief with needle nose pliers (to keep heat from melting the wire insulation in the strain relief). Then heat the crimp connector and just “touch” the spot next to the pliers to just “wet” and “wick in” a tiny bit of solder. Too much will fill in the part that engages the little “lip” in the housing and prevent the connector from locking into the housing.

    You can do without the heat sinking pliers if you are “good at” soldering, use an iron with the correct temperature and use a nice low melting point lead/tin/silver soldering alloy. If you use lead free solder, the heat sink pliers are a must due to the higher melting point.

    Remember, just “wick in” a tiny amount. Too much solder will ruin the crimp connector. I suggest practicing on a few scrap parts first.

    If you need several male ends, do this: snap off the needed length of long male header pins, then slide the crimp connectors onto each pin (the long side). After soldering each one, carefully remove the plastic piece that holds all the pins in a row, insert the pins into the housing, then finally slide the little plastic part back over the pins (install the plastic part with the “larger” holes toward the connector).

    This will help hold the pins in perfect alignment, making it easier to plug a large connector assembly into the board.

    The resulting male pins will be a bit too long to insert all the way into a female connector, but I suggest that you do not cut them shorter because the resulting burr on each pin will damage the female connector after repeated use. If you do trim the pins, use a tiny file or a razor blade to clean off the rough burrs on the end of the pins. Be careful with sharp tools!

No public wish lists :(