Portable Bluetooth Speakers

Back in 8th grade when I had a lot more time on my hands, I always wanted to build a decent pair of speakers.
I had built several speakers back then already: some were literally just speakers with an amplifier circuit, all exposed
some were speakers people threw out and I modified them
most of them were just ugly, delicate, and not presentable or usable in everyday conditions.

This folder of links has been on my Google Chrome browser for 4 years:

The links that I told myself I would look at eventually:

• http://ccs.exl.info/cust_cr.html - this link was useful for finding out what components I needed to build a real nice amplifier circuit
• http://www.diyaudioandvideo.com/Guide/BuildSpeakerBox/ - this page gives data for calculating what the dimensions of your speaker box should be based on what tones you want to resonate most. It also gives data on what material you should use for your speakers, and what find of damping structure you should put inside your speaker box.
• http://www.circuits.dk/calculator_multi_layer_aircore.htm - calculating the amount of turns you should have on an inductor coil for optimal bass response
• http://www.jlaudio.ca/header/Support/Tutorials/Enclosure+Bracing/Tutorial%3A+Enclosure+Bracing/624625 - this discusses the structure inside your speaker box so that air can move through it 
• http://www.instructables.com/id/DIY-Hi-Fi-WiBAQ-Speakers/#intro - general instructions on how to build speakers!

As you can see, building speakers is a very involved process. This is probably the reason why I did not go forth with this project back in 8th grade: the amount of things I needed to consider were daunting and I put it off.

• I would need to consider how much money I wanted to spend on what type of amplifier circuit: Class A? B? C? D? each class gives a different sound quality, but A is much more expensive than D, and much less power efficient. It's the difference between vacuum tube amplifiers, and a regular transistor based amplifier:
  
  vs
• I would need to consider the shape of my speaker and the structure inside. There are two ways to approach this: a ton of trial and error or a ton of math.
• I would need to consider what material I would build my box out of. Should I use the acrylic sheets I have lying around, or should I invest in MDF board for higher sound quality?

So I never took the time to consider all these things.

Yesterday I looked at the project again for the first time. I realized that sometimes you need to stop thinking and just do: otherwise you stay stuck. 

Here are the plans for the speaker:

• Triangular prism shape (like a Toblerone box)
• Build out of acrylic sheet, covered with faux leather
• Wooden end caps 
• two speakers in the front, two tweeter speakers on the side
• Class D amplifier (This time around I don't think I want to get involved with figuring out circuitry, so I'm going to use a prebuilt Class D amplifier, the PAM8403. It's low voltage, cheap, and relatively high quality)
• Bluetooth and auxiliary connectivity!
• 2600mAh rechargable battery

It might not be the highest quality or the most optimal design, but it's better to start something than to not do anything at all.

Here is the progress so far.

You need an 11" x 14.75" sheet of acrylic

Some random trash for dampening the inside of your speaker box (this is so that when the speaker shakes, the whole speaker box doesn't shake and cause distortion)

Speakers and tweeters

Switch, PAM8403, some nuts, LED + resistor (for power indication), 100uf capacitors for the high pass filter for tweeters

Cut the sheet to size

mark down where you need to bend it (for the equilateral triangle shape)

mark out where you need to cut the holes for the speakers

nice fit!

attempt to bend plexiglass

 This is where I stopped.
Along with needing to acquire a bluetooth module, a battery, leather, wood, and an audio jack, I also needed to buy a heat gun.
Usually when I bend small pieces of plexiglass I use a cigar torch lighter:

I don't have a nichrome wire heating element to bend a whole sheet this large...

For now this project is at a pause, but I will keep updated on the progress!

BANG BANG Zippo Engraving

I haven't written a blog post in a long time (for more than a year actually). This is mainly because I find Instructables.com to be easier to put work out and document steps with.

http://www.instructables.com/id/Hand-Engraving-Zippo-Lighter/

But since I have English assignments to write blog posts, I think I will resume again.

This was a project from a year ago but I never got around to documenting it.
Last summer I got obsessed with Zippo lighters. I always loved lighters beforehand, but I thought these were especially cool.
The difference between a Zippo and a regular Bic: Zippo uses wick and lighter fluid while Bic is butane. Zippo likes to brag about their windproofiness which actually isn't that great.

I bought a lighter for $7 and I really wanted to personalize it. Beforehand it looked like this:

Just a regular chrome lighter.

 Afterwards it looked like this:

yeeeeeeeeeeeeeeeee

So I'm going to go through the steps.

First you want to figure out what you want to engrave. You want to scale it and print out the design (actual size) on paper.

These  the concepts. As you can see it says "BANG" on both sides, and when the lighter is opened it says "BANG BANG" haha clever right?!








Then you print them out.

So after printing out the stuff correctly on paper, put some glossy tape over the paper

Then you put on masking tape where it printed. Feed the paper back into the printer and it should print back on the masking tape. We're essentially printing out a sticker. The glossy tape is to assist removal of the masking tape.

 This was my first time ever engraving something, so I wanted to engrave a piece of scrap metal before ruining my $7 lighter. I found a CD player case and engraved the draft on that.

Put the masking tape on your metal

Use an exacto-knife to cut out the letters

Fill in the metal areas with sharpie. This way you can tell if a section has been engraved or not; color indication.

I couldn't really take pictures of the dremel in action because that would be dangerous, but this is what happened.

Not bad. Time to move on.

So I basically repeated the steps for printing. This time you see I used lighter colored masking tape.

Before you engrave, take out your insert. If it's filled with fluid, you might want to put your insert in a ziploc bag so it doesn't evaporate.

Tape your lighter case shut.

Place your sticker masking tape over where you want to engrave. This step is IMPORTANT. Make sure you place it right.

Start cutting out the letters with an exacto-knife.

This is how you peel out the letters.

It's all cut out.

Color in where you want to engrave.

Not real live engraving footage but you can see the idea. 

My garage is really dark.

As you can see, Zippos are brass. I can tell I'm done engraving a letter when I see brass and not blue sharpie.

One BANG done.

It look's pretty nice.

After you're done engraving, take all the tape off and wash off your lighter with acetone.

Annddd you're good!

Appreciate your shiny brass for one day before it starts oxidizing and getting dull.

So that's how I engraved my Zippo for the first time. It took a lot of effort.
Over time I got lazier when I engraved things. Below is a video of another lighter engraving I did. It requires less steps and yields pretty much the same results.
Bask in all of it's over-editted glory and admire the edginess of the lighter.

Thanks!