Apple Keyboard Power Cable

Get power from USB instead of batteries

I have an Apple Wireless Keyboard that I love, but it runs on batteries. This little project is how I put a USB wire on it to make it work without batteries. It’s still a Bluetooth keyboard, it just runs off of USB power.

The Parts

To complete this, you’ll need:

• Apple Wireless Keyboard MC184LL/A (if you’re reading this, I’ll assume you already have one)
• 2 AAA to AA Battery Holders
• AMS1117 3.3V 1A Voltage Regulator
• USB Cable (any kind)
• An Apple battery cover (optional)
• Soldering iron, wire, hot glue, and miscellaneous tools

I got all of it for about $16 (not including the keyboard).

Assembly

1. Drill the metal bits

You’ll have to drill holes in the battery cover and the “negative” end of one dummy battery. This was by far the trickiest part.

Holes!

Make the holes just big enough for your USB cable to pass through with the insulation. I was not confident in my ability to nail this on the first try and I didn’t want this to be a permanent conversion, so I bought another battery cover from eBay. If you’re really committed, you could drill the one that came with the keyboard.

2. Run the wires

Here’s what I’m calling the wires involved:

• New red: A wire you supply that will connect the V_out pin of the AMS1117 to the positive contact inside the dummy battery.
• New black: A wire you supply that hooks together the ground of the USB cable, AMS1117, and negative contact inside the dummy battery.
• USB red: The red wire that’s already inside the USB cable. It will supply +5V to the AMS1117
• USB black: The black wire that’s already inside the USB cable. It is the ground for all components.

You’ll need to drill holes in one end of each battery so a wire can run between them. Run the new red wire all the way through one of the dummy batteries.

The positive battery contact

Cut the end off of your USB cable and find all of the wires.

Start by ruining a perfectly good USB cable

Push the USB wire through the drilled battery cover and negative battery terminal. If you buy the same dummy batteries I did, the ends pop out. That’s useful for soldering wires to the metal bits without ruining the plastic bits. You have to solder:

• The new red wire to:
  • the positive end of a dummy battery and
  • pin 2 of the AMS1117
• The new black wire to:
  • the negative end of the other dummy battery and
  • the usb black and pin 1 of the AMS1117
• The usb red to AMS1117 pin 3

Here’s the pinout from the chip’s data sheet:

The pinout for my chip

When you’re finished, it will look kind of like this:

All soldered up

3. Test it

Hook the USB cable up to a power source and make sure you get 3.3V between the positive and negative terminals of your dummy batteries.

4. Glue it

When I was done with soldering, I put a glob of hot glue on the usb wire and pulled it down into the dummy battery so it doesn’t move. Then I assembled the batteries and glued the gap between them to keep them stuck together.

Finished unit

The battery cover is not glued to anything. It can spin on the cable. To hook it up, just take the batteries out of your keyboard and put this thing in instead.

All hooked up

Standing Desk Converter

I’ve been thinking a lot about health lately, thanks to Clairvoyant’s health challenge. And I’ve been reading about the health benefits of a standing desk (or maybe not).

You can buy standing desk converters like these:

• Ergotron Worksurface for WorkFit-S
• Workez Standing Desk Adjustable Sit Stand Desk
• Ergo-Stand – Convert Desk to Stand Up Desk

But they start at $75 & they don’t look great, so I decided to build one. I prototyped it with stacks of books and came up with a 12″ rise for my keyboard and a 20″ rise for my laptop on its mStand. The mStand isn’t required, but I use it when I’m sitting so it might as well stay. 18″ wide is enough to hold a keyboard and trackpad comfortably.

I built it out of some 3/4″ cherry ply I had leftover from the desk. I routed the edges so they’re rounded and I put a brace at the top of the back to hold everything square.

If I were to build it again, I would change some things:

• move the legs in about 3/4″
• have shelves overhang the riser by about 3/4″
• blend the roundover more carefully into the lower shelf
• use a wider brace so it’s more certainly square

But that stuff is minor. I’m pretty pleased with it.

There, I Solved It

I was inspired by http://thereifixedit.com. I feel a kinship with the innovators whose work is featured there. After all, I just expanded my universal remote, and they built one from scratch.

I decided to document my own attempts at problem solving. Hopefully the engineering is better than theirs, but I feel confident my problems had less reason to be solved in the first place.

The Problem

Sometimes I forget to close my garage door. I’ve left it open all day and all night. This is a perfect example of a problem that barely needed to be solved in the first place. Right in my wheelhouse.

Solving It

What I need is an unmissable indicator of my forgetfulness. I’m thinking of a light that comes on when the garage door is open.  Ideally, one that I can see while watching TV or laying in bed.

Design

The concept is simple:
There’s an LED, a power source, a switch, and a couple resistors.

Parts

The switch is a magnetic reed switch. It’s normally open, but if a magnet cozies up to it, it gets all closed. Perfect. I don’t know the model number, because I just found it in my garage, left over from when they installed the security system. You could get one for about $3, and you could go wireless for $50.

The power source is a couple of AAA batteries. I happened to have a battery holder that size lying around, so that’s what I went with. I think you could get a new one for $2.

The LED is a panel mount model I bought just for this. It is green, and snaps into a 1/4″ hole.

According to my math, I need a minimum of 40 Ω of resistance to avoid burning up my LED @ 3V. All I had were a couple of 100 Ω resistors, so I went with that. In parallel, that gives me 50 Ω plus the resistance of the wire & switch, so I won’t burn the LED up.

Then there’s some miscellaneous wire, solder and heat-shrink tubing to keep everything neat. Oh, and a magnet. I happened to have one of those too.

Assembly

Most of the stuff sits inside the house. I picked out a nice location in a closet and drilled a hole for the LED. I soldered up the battery pack, resistors, LED, and the leads to the switch and fed them through into the garage.

At the other end, I just had to stick the switch in place and mount the magnet to the garage door. And by “mount,” I mean “stick it to the garage door because it’s a magnet.”

Victory is Mine

After just a little tweaking to get the position of the magnet just right, I have a working light. It has already reminded me to close the garage door once, and I expect it will have a long life saving me from myself.