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Member Since: April 10, 2010

Country: United States

  • As far as MOS biasing, it’s virtually the same as BJT. Main differences are square law vs exponential relationship between current and voltage, and you get infinite input impedance at the gate (MOS equivalent of base) so ‘ib’ = 0 for MOS. All of the main ideas (and schematics) are the same.

    As for the circuits shown here, resistor biasing is OK, but if you need any control over the actual current values then you’ll want to go for something a bit more sophisticated like using a ‘diode connected load’ or a current mirror. Perhaps those would be good videos for the future as well?

  • This will depend on your desired output frequency. From the datasheet’s specs on communications (pgs 4-5), the worst case command time is 1.4uS per bit, 24 bits per LED plus 50us reset per command. This gives the equation: (#LEDS)(1.4uS)(24) + 50uS < (number of uS in output period). In my case, I want something that can operate ~50Hz so it looks smooth to the eye. I get: #LEDs < (20000uS - 50uS)/((1.4uS*24) = 593 LEDs. Note that your controller needs to be able to control it’s output within +/- 150nS. Seems like a 32MHz mcu could do this if you put everything in a timer/interrupt routine and didn’t try to do anything else. Could someone verify this?

  • Hey guys,
    I tried to look through the linked github site but was uncomfortable using the C files with my arduino files. I looked around to see if someone had done this in processing/Arduino and found this man’s site:
    I had my sensor up and running in very little time, the only change I needed to do is set the serial port used in his processing code to the one listed under the ‘tools’ tab in Arduino. Also note that he changed the baudrate to 19200 in the on-board version of the code.
    And out of curiousity, could someone point me to a tutorial that tells me where to put all of the files given on github and how to make them?

  • Is this a standalone device or do you have to have a microcontroller? I’m trying to make a small short distance radio to connect wirelessly to my iPod and don’t need a lot of bells and whistles, but would like is very small.

No public wish lists :(