Know How... 83

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

• Go to Seven Bits Mac-Linux USB Loader to download the software.
• Download the Distribution of Linux of your choice, I chose Ubuntu
• Create Live USB

* 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

• 1 x Blue SMD LED Strip - 12v
• 2 x Red SMD LED Strip - 12v
• 2 x TIP31C Transistor
• 1 x 3.5mm Stereo Plug
• 1 x Heat Shrink Tubing
• 1 x 25ft Length of 20ga black/red wire
• 12v Power Source

Tool List

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

The Process
Dancing LED Schematic

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• Transcripts: Know How... 83 (Transcript)