The end result is a constant fade up and fade down just like a Mac on standby.
Try it! See how small you can build it.
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Step 1: Gather Tool and Components
470 ohm resistor (or a resistor to drop the current for your desired led from around 8 volts.)
33k resistor ( or a 100k potentiometer for adjustable fade times)
LED ( I used Blue)
Generic NPN Transistor
Copper clad board. breadboard, or project board.
Dremel or other rotary tool for drilling
1/32" drill bit for wires
Cutting wheel or tin snips if necessary to trim board down
Scotchbrite pad or fine sandpaper. ( I used sandpaper because it happened to be there)
Muriatic Acid (concrete cleaner or pool chemical) Home Depot and other hardware stores have it.
Hydrogen Peroxide (standard wound cleaner) Found in drugstores, grocery stores, you probably have some at home.
Latex or Nitrile Gloves
Acetone to clean ink off of board after etch.
Outdoors area to etch in
Plastic or glass container to put etchants in.
Helping Hands clamp with magnifying glass (nice to have a third hand)
I've included the files for Express PCB software. Free download.
Step 2: Breadboard it
Pin 1- To Ground
Pin 2- Jumper to Pin 6, Jumper to Base of NPN
Pin 3- 33k resistor to base of NPN
Pin 4- Jumper to Pin 8
Pin 5- NC
Pin 6-Jumper to Pin 2
Pin 8-Jumper to Pin 4, Connected to Positive voltage
Emitter of NPN to 470ohm resistor to LED
Base of NPN to + side of cap, then ground - side
Collector of NPN to + voltage