Know How...

Mar 6th 2014

Know How... 83

Linux on a USB and Sound Controlled LED

Why you should understand DNS, make a bootable Linux OS on a USB, and control a string of LED's using TIP31 transistors.

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Category: Help & How To

Why you should understand DNS, make a bootable Linux OS on a USB, and control a string of LED's using TIP31 transistors.

Check out our transcripts.

Making a Bootable Linux USB Drive

Step 1: Get a USB Drive

  • You'll need a USB flash drive of at least 2GB or more.
  • Format the USB Drive by using Disk Utility and use MS-DOS (FAT)

Step 2: Download the USB Loader

* This process should only take about ten to fifteen minutes.

Step 3: Reboot

  • Reboot your Mac, on startup when you hear the "chime" hold the "alt / option" key to choose your boot method
  • Select your USB Drive, press 1 to load Linux.
  • Congrats you have a portable USB OS!

Links:
Seven Bits Mac-Linux USB Loader
Mac-Linux USB Loader on GitHub

LED lights & TIP31 Transistors

LED Lights

  • LED stands for "Light Emitting Diode"
  • Diodes only allow current to pass in one direction - positive to negative
  • LEDs are low-cost, efficient light sources
  • SMD (Surface Mount) LEDs can be found in rolls backed with adhesive

TIP31 Transistor

  • It's a NPN (Negative-Positive-Negative) bipolar junctions used for medium power applications.
  • We're using a TIP31C -- which is capable of 100v and 40 Watts
  • Pin 1 and 3 are a junction. Used by a lower-power circuit.
  • Pin 2 and 3 is a semi-conductive pathway.
  • When a charge passes between junction 1 and 3, it allows a charge to pass between 2 and 3.
  • Where this becomes useful is that the charge passing between pin 1 and 3 can be small while the charge passing between pin 2 and 3 can be large.
    • The voltage from the headphone hack of a media play is 1-2 volts, perhaps 20ma. That would never be enough to drive a LED strip.
    • HOWEVER... we can use that small current between pins 1 and 3, to trigger a much larger current between pins 2 and 3.
    • If pins 2 and 3 are the negative side of a 12 volt, 2 amp circuit, then we've just created something useful!

Sound-Sensitive LED Lights

Parts List

Tool List

  • Soldering Iron
  • Scissors
  • Wire Stripper/Clipper
  • Lighter
  • "Helping Hands"
  • Needle-nose Pliers

The Process
Dancing LED Schematic

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