The Marquee Clock

[zeke 693]

Lately, I have been admiring my whizzy cool LED strip full of WS2801Bs.

 

I have it laid out along my desk and it's making neato colors and patterns all through the night.

 

My kids are fascinated with it.

 

So, last night, a thought popped into my head spontaneously "I wonder what my Ikea clock would look like if I put these LEDs in behind it?"

 

Today, I ripped apart the Ikea clock and stuck the LED strip loosely in behind it and made an animated GIF of it in action.

 

I like what I see so I started work on a new project called The Marquee Clock.

 

 

 

What do you think?

 

I have started a blog series about the design and development process on my personal web server. 

 

 

 

@bluehash: I would love to store this image on 43oh.com but it's too big to upload.

[Fred 453]

What's the plan? Something like @Greeg's LED ring clock? Or just 12 LEDs to give you the time to the nearest 5 minutes - which if we're honest is all the accuracy we ever really need.

[zeke 693]

The plan is to entertain the kids. They love the clock idea.

 

I also want to make a design that can be retrofitted into that $2 Ikea clock. That way, I don't have to worry about an enclosure.

 

I haven't made any decisions on what brain to use or on how to mount the LEDs though.

 

A part of me wants to put a CC3200 in the design so that I can fiddle with the LED patterns remotely. For example, I could program the clock to do something special on each kid's birthday so they see it in the morning when they wake up. 

 

And, that Ikea clock is a perfect LED diffuser so the LEDs will have to face into the plastic and not towards the wall. 

 

In the end, my kids will be pleased because of binky rainbow lights, I will be pleased because I made something new and I will have another product in my portfolio. Additionally, it is best not to have idle hands.

 

 

 

[zeke 693]

I decided to simplify this design significantly to reduce the complexity and to increase the likelihood of completion.

 

I re-examined the physical structure of the Ikea clock 

 

 

and took some measurements

 

 

and decided the best thing to do is to make a single ring that will hold all of the LEDs and pretty much nothing else.

 

 

The board will attach to the clock housing with the use of 3M 300LSE adhesive transfer tape. The board will contact the clock in the black hashed area.  The clock housing has a flat ring that will gladly accept the 300LSE. That flat ring is visible when you flip the clock over (see above photo).

 

 

 

I will make another board to drive this one with power and control signals.

 

This board will be just a peripheral that fits a $2 clock nicely.

 

Hmmmmm... I wonder if I should put another ring of LEDs on this?

 

 

 

 

[zeke 693]

It turns out that WS2812B LEDs are affordable in bulk.

 

I think this looks better.

 

 

 

 

[zeke 693]

After researching what other people like @@greeeg has done with their ring clocks, I decided that I would like to change things a little bit.

 

This is what the ring looks like tonight.

 

 

I decided that one ring of LEDs was sufficient to satisfy clock functionality. Lowering the LED count will also reduce the maximum amount of current this will consume. 

 

I also decided to try out a different LED. I hear that the APA102 is much easier to talk to than the WS2812B.

 

Current consumption is 20ma per color or 60mA total when at full power.

 

It looks like the price hovers close to $0.20 USD on eBay when purchased in large quantities.

 

 

In its single piece state, this ring will cost about $200 USD (shipping included) to make a quantity of four (4) at Quickturn in South Korea. Yikes!

 

So, I will be slicing up the ring into four pieces to save on fab costs. 

 

Also. I think I will have to search for a fab house who will make this in white.  Anyone have ideas on that?

APA102 GREELED.pdf

[zeke 693]

After checking into pcb fab costs, I took the time to break the ring down into four parts. The pcb looked like this:

 

 

Fab costs of this were around $15 a piece since it's 4.5"x4.5" when looking at a square bounding box.

 

Something didn't sit right with me on that so I tried a new direction - flexible pcb. 

 

So, I started playing around with the layout to see what I could come up with. 

 

I figured out the circumference of the plastic housing to be C = pi * D = pi * 18.6 mm = 584.33mm.

 

Then, I fiddled around with part placement until I got 60 LEDs equally placed along the 584mm pcb. The perfect spacing turned to be 9.7mm.

 

This is what that looks like:

 

As I started to route the pcb, I noticed that the power and ground traces were not linear. They were staggered all over the place. So I decided that there was a more efficient way to make this happen. 

 

I rotated all the LEDs 90 degrees and checked the routing again. This time, the power and ground traces were linear and the signals were slightly twisted. Since they carry only intelligence and not hight current, I decided that they can remain twisted.

 

This is what that routing looks like:

 

 

At this time, I am thinking that I will put pads at the end of the strip so I can either solder on wires or crimp on a 0.100" connector. It's all about the current capacity of that unknown connector.

 

You may notice in the previous picture that the strip is longer than 584mm. There is intentional overlap. That overlap will allow me to create a connection point

 

This is my first attempt at the connection point:

 

 

I have to decide what to do in this area but this will fold over and stick to the backside of the clock housing and give me more room to put stuff on. 

 

 

[RobG 1,892]

Instead of making your own PCB, how about using standard strips?

You need to make a small tool, little bit wider than the strip, with shallow V on one end (or you can try to find jeweler's bending pliers.)

Bending strip on one side between LEDs will arc the strip.

I did a test once to see if I can make arcs and circles for xmas displays, and that worked pretty well.

[greeeg 460]

Strips would be the way to go cost wise, you can get very desnse ones at 144 LEDs/m (these are probably too dense to bend inwards. but would work outwards.)

 

The only downside is the standard spacings, which very much limit the different radii of your circle if you need to maintain exactly 60 leds.

[zeke 693]

Thanks for the ideas guys. They are viable alternatives.

[abecedarian 330]

What if instead of having the LED's facing 'forward', they were wrapped around a tube of sufficient diameter, and faced 'outward' or perpendicular to the center of the clock, and had a ring of Lucite or other acrylic that directed the light towards the face of the clock?

 Something like:

c     |\
l f   | \
o a   |  \
c c   |   \
k e   |    \
      ^^^^^^
        LED
      ------
       tube

Seems it'd be easier / cheaper to make the Lucite / plexiglass ring than to do multi-segment PCB's.

[zeke 693]

@@abecedarian

 

You are describing my design intentions perfectly. 

 

If you look at the photo of the clock housing, you will notice that there is a circular face that is perpendicular to the clock face. 

 

 

It is my intention to create some sort of pcb that will allow me to stick 60 LEDs all around the clock housing on this perpendicular face.

 

The animated gif above shows the WS2812B strip in action. The LEDs are loosely mounted on the perpendicular face and so they are pointing outwards. 

 

When the LEDs point outwards, the housing scatters the light perfectly and the clock then looks like it's a neon light tube.  Very cool!

 

Note:  

 

I realize that an LED ring clock is no longer a brand new adventure for people to charge into. A quick google images search on LED ring clock brings up some nice images. Yet, no one has figured out how to give this idea mass appeal.

 

In this thread, I have been openly working the design process to illustrate my train of thought so that people could see what the decision making process looks like.

 

I used the Ikea clock as a starting point because it is a perfect light diffuser and it is readily available at $2 each. Anyone can afford that.

 

I also had an LED strip on the table that the kids wanted me to use for Christmas lights. On a lark, I put it behind the clock housing to see what it looks like. The kids went bonkers for it!

 

So, I started experimenting with various design compromises to see what the resultant manufacturing costs become. First a ring pcb, then a quarter arc and finally a custom strip.  The custom strip is my preference because it will be a stick-on installation and the LEDs will point the way I want them to.

 

Once I get the hardware figured out, the software will become a brand new adventure. Besides clock functionality, what other functions ought to be included? Patterns? Temperature? Alarm Clock capability?

 

[abecedarian 330]

@@zeke

I might suggest just simple, small, postage stamp size boards each carrying one LED- something just big enough for the LED and some wire-pads, and you can chain them together using regular wire or ribbon cable. A simple wrap around the 'core' using something like foam tape or the DIY type foam weatherproofing stuff, then wrap the little boards around it, and maybe a piece of clear acrylic or even poster board ring over the back to enclose things. Heck, you could probably just 'dead bug' them together with short pieces of wire interconnecting things.

 

A benefit to this is that if one LED stops working for whatever reason, it's easy enough to just replace that one board.

 

To keep things 'simple', an F5529 might be useful since it has an RTC built in?

[zeke 693]

@@abecedarian

 

Yes, Good idea.  I pondered that as well over the weekend. 

 

But then I realized that I could buy a 144 per meter APA102 LED strip, cut them apart, then solder them back together with the spacing that I desire (9.7mm between LEDs).

 

I'll probably do this for prototyping.

 

 

 

 

 

 

 

 

[zeke 693]

As far as the processor goes, I was thinking of using this module for fun.