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)!

  • Are these switches “tactile” (that is, clicky like a microswitch)?

  • Depending on which Arduino you have, try setting the analog reference to 2.5V or 1.1V. This will make the FULL SCALE analog input (i.e. 1023) to be 2.5 or 1.1 volts, giving you more “gain”.

    Note though that since you get a no signal offset voltage reading of 300 (which is 1.47 volts with a 5 volt reference), you will need to level shift the audio output signal if you use a 1.1 volt reference (because 1.47 volts is more than 1.1 volts and it would “peg” the analog reading at 1023).

  • This mic works surprisingly well, but one word of warning: Do not connect the audio output pin to a low impedance load. My son was playing with the mic and tried to connect a small 8 ohm speaker directly to audio out and ground (with a +3.3V supply). The little op-amp on the board was killed by this. I don’t know what the minimum recommended load impedance is, but probably to be safe send the signal to at least a 1K load or more…. maybe at least a 10K load.

  • 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.

No public wish lists :(