Alarm clock project: landing page

This is a landing page for my alarm clock project. There are three posts on this project, so I though it would be helpful to have one overview page that I can direct people to.

I have a cheap plastic alarm clock that had small buttons, specifically the alarm off button. So I wanted to replace them and mount bigger buttons (I added a big snooze button too). I used Adafruit's small and simple arcade buttons (which I've described in this informative post, in case you want to know about them for your project) and wired them to the button contacts on the inside. I took out the CD player to make room for the buttons cut holes in the top to mount them. It turned out great in the end.


First post: initial opening and beginning research
Second post: cutting

Third post: installing buttons and final look

Finished project

What it looks like inside.

Alarm clock project 3: installing buttons, final look

First post: initial opening and beginning research
Second post: cutting

This is the third post.

This post is how I cut holes for and installed the buttons. There are pictures at the bottom for how the alarm clock turned out.

I used this hole-saw drill bit, which was 1'', and I needed something a little bigger than 1 1/8". 1 1/4" would be too big.

Clamping the lid. I put a wooden spacer underneath that was flush to the lid. This way the underside of the cut would be cleaner.

Pictures after drilling.

Here you can barely see the pencil outline of the desired hole. I have to sand away that much.

Poor man's sander. After sanding by hand a bit, the sandpaper taped around the hole saw would fit. This method worked pretty well. First I sanded it by hand, then spun it with a drill. I was careful not to let the hole saw slip or cut me while I held the lid.

 Sanded holes.

Test fit, it worked well.

Test fit.

Mounting the button circuit board.

These mounting posts originally held the CD player circuit board too, so I had to substitute these extra silver washers to make the screw tighten.

Here's how I soldered the buttons. I just connected them to the leads of the existing buttons so that they would still operate.

I left enough slack in the wires so that one could open the lid and see inside and so that they could bend easily to a good closed position.

Here's soldering the wires from the backup battery (for when the power goes out). This is the first time I used heat shrink tubing; I heated it with a lighter, which worked well enough.

As you can see from the above picture, I forgot to put the wire through the hole in the circuit board before soldering back together. So I had to cut it, put it through the hole, and solder it again (it wouldn't fit around). :P

 Closed lid.

How the wires reach under.

Finished alarm clock.

What's visible when you open the lid.

Hope you thought that was interesting!

Alarm clock project 2: cutting

First post: initial opening and beginning research
This is the second post.
Third post: installing buttons, final look

So I completely finished this project a little over a month or so. It's taken a crazy long time for me to post on it since I first started (Nov '11). Sorry about that for anybody who reads this and notices the discontinuity. I'll finish it up today.


I wanted to install bigger snooze and alarm off buttons on my alarm clock for ease of use. Read the first post for more information.
This post is about how I cut the unnecessary plastic away with a hacksaw. (cutting the holes for the buttons comes next.

First I figured out where the holes should go so that I know what is in the way. With the data sheet and a caliper I figured out the correct size of the hole. These buttons have clever clasps/latches/"wings" that push out on the hole to keep the button in place. These flex like a spring and adapt to a range of hole sizes, so I didn't need to be super precise. I drew the hole size on some graph paper with a compass so I could check the placement and draw around it on the alarm clock. The hole in the middle of the paper is for lining it up with the center lines I drew on the alarm clock (using the lines in the graph paper).

I'm using the darker circles closer to the center, as opposed to the lighter ones near them.

Underneath the cover, inside the clock. The dark, straight lines is where I'll be cutting material away. After establishing the placement of the buttons on the top, I measured up and over from the edges to be able to transpose the positions on the underside.

Another view.

The underside for reference.

I cut the plastic with a hacksaw blade. I protected my hand with some duct tape on one end. You can see my crude hilt for slip protection. :) (The alarm clock top has been removed.)

I basically took some diagonal cuts that were increasingly shallow. I sanded and filed the edges when I got close enough.

 Half way through I realized I could test the buttons on the center hole for the CD player spinner. It worked ok, but was a little loose. When it slipped into the hole I stabbed myself on that sharp corner near the laser symbol. :(

One side finished. The rounded corner was first cut a couple of times with the hacksaw blade, then sanded a bunch.

The other side.

Finished. I sanded all the edges to make them smooth, including the edge on the CD circle that already existed. It was painted silver and it contrasted with the true black plastic color from the cuts nearby.

Alarm clock project 1: initial opening and beginning research

This is the first post.
Second post: cutting
Third post: installing buttons and final look

My one complaint with my alarm clock is that the off button is very small. This is the button that turns the alarm off in the morning after it has gone to snooze a couple of times. So naturally you would want it to be big and accessible like the snooze button. But it's not. I thought it would be cool to modify the clock and add a big ol' mash-and-be-done button in its place and just solder the electrical connections to where the original button was. (Later I decided to throw on a bigger button for snooze while I'm at it).

Here's a bunch of the parts after it has been taken apart. The circuit board for the buttons was on the top, but you had to get to it from the bottom, so out comes everything in the way. Namely, the main "motherboard" and the CD player components.

And here's the rest of it! I still need the alarm clock, so I'm using the main circuit board while I'm working on this project. I have to use headphones and the clock's headphone jack since there's no speaker attached anymore. With the volume turned up they are loud enough to wake me up. The clock runs fine without the CD player attached. There's a transformer that takes the house current down to something reasonable, but it's still unnerving to handle a big messy open circuit that's plugged into the wall outlet...

Some inspirational parts:

On the CD player this gear is mounted by this unique piece of plastic (the curvy piece with three parts/arms). It's thin and designed to be flexible so that if the CD read head is driven too far and jams, this part shifts and flexes instead of breaking the gear.

This is how the radio tuner works. It shows which station you're on by this white, plastic-rubber piece. It curls up around the tuning wheel, to which it is attached. It curls and uncurls as you turn the wheel, moving right and left.

Here's a limit switch that has two flat, bendable contacts that are pressed together by a lever when the CD cover closes.
This is the opened position.

Closed position.

A similar switch on the CD player assembly. It's the black and clear plastic extending down from the circuit board in between the two motors. The two metal contacts are visible.
Open position.

Closed position.

Initial Project Pictures

Here is the front of the clock showing the size of the buttons. The button tops are a two plastic molds that press on small tactile switches.

Here is the power button area. I've drawn reference marks on scotch tape stuck on the clock. The paper is a stencil of the circuit board that goes underneath.
The shaded area with the X is the only area I can cut and put a button into. There is only a quarter of an inch of depth underneath that (the same size as the grid on the paper). This is not very big compared to what I had in mind, which was to cut away nearly all the available material underneath the power button and put a big ol' button there. Because of structural components that can't be cut away and the button circuit board's ribbon cable, that shaded part is all I have to work with.

I decided that's not enough and I'd have to find a different solution. There weren't any good buttons available that would be as big as that space but not very deep. I also didn't want an unsightly skinny or tall button. I began to think of other places were I could put a button and rout wires to it.
I realized that I could put a button right into the middle of the CD cover. I could leave out the CD player assembly and have lots of space to work with. I never listen to CDs on this clock anyway. Now that there's tons of room, I'm going to put another button for snooze.

I picked Adafruit's new arcade style buttons because they're cheap and look great. They're translucent and have room for an LED, so I might fit one inside and wire it to the button leads so that it lights up when pressed. Hopefully there will be the right kind of current to run the LED.
My other button option was this more boring one from Digi-key.

The total depth that extends down from underneath the button lip is 31.7 mm (from the details tab on the product page). It does not extend far enough to reach where the main circuit board is mounted. I've checked with the circuit board in place and there's tons of room for the button and routing the wire.

Here's another view. The short post is for mounting the CD player and the tall post is for mounting the main circuit board. The penciled line is the limit.

So now I will plan out the size of the buttons and where I'm going to mount them. Then when they come in I'll  inspect them more, cut the holes, mount them, solder them to wires and solder those to the contact points of the original buttons.