Bulbdial clock - Thoughts on build and question on shadows

williamlee

I just finished my bulbclock build last night.  I had a lot of fun with it, and it almost went off without a hitch.  Everything was fine until I got to the red LED ring and was connecting it to the clock.  I thought I had a potential solder bridge between one of the LED connectors and a leg of a red LED, and in my enthusiasm to cut it, I ended up twisting and lifting one of the LED leg pads off the PCB.  I tried not to panic despite the other LEDs going crazy when I tried to light the problem one, and followed the trace to the next solder point.  Luckily it was very close and I was able to solder a very tiny bridge made out of a cut off LED lead.  It worked like a charm.  In reading other troubleshooting posts, I guess the erratic behavior with the pad lifted was due to charlieplexing and one LED being missing.  Anyways, as always great kit.  I'm decent with electronics at this point, but it's so nice to see a very well labeled, thought out kit and instructions.

My question is related to a very large shadow that the LEDs cast.  In reading other posts, this appears to be due to the newer wide LEDs that were chosen for more recent kits.  What was the reasoning behind using these versus the older ones?  Is there anything I can do to minimize the size of this shadow from the LEDs?  It makes it almost impossible to see the minutes hand when it is overlapping.  I believe the LEDs are all mounted correctly so I don't think that is coming into play as a factor.  Thanks for any suggestions!

Oh one other question, I also ordered the rear projection back but currently have mounted the white one.  Dumb question, but what is the difference between the two?

wbp

I also found the light pattern from the LEDs to be a bit wide, and in some cases diffuse.  The folks at EMS tell me they are 20 degree (viewing angle) LEDs.

I poked around a bit and found some 15 degree Cree LED's on Mouser that I like.  I ordered a small quantity to try and I think the pattern from these is nicer and more focused.  I've ordered enough to replace all the LED's in my clock.  It will be interesting to see how it looks once I've made the switch.

If you're interested, here are the Mouser part numbers:  

Blue: C503B-BAN-CY0C0462  $0.14 each

Green: C503B-GAN-CB0F0792  $0.19 each

Red: C503B-RAN-CY0B0AA2  $0.23 each

William

Windell Oskay

Originally, we had planned to use wide viewing angle (40-degree) LEDs in the kit, but we were unable to get the right ones in time for the initial launch of the Bulbdial, so we used standard narrow-angle (~20-degree) instead.  A year or so later, when we were finally able to get the wide-angle LEDs in the right quality, we began shipping those in the kits.  These are pretty neat because they light up nearly the whole face, making neat cyan, magenta, and yellow shadows with a white background.  However, even though it was a better set of LEDs in certain ways, most people turned out to prefer the look of the narrower LEDs, and (for better or worse) we were somewhat forced to switch back to the original (narrow-angle) LEDs.  

My expectation, since you got your kit recently, is that you *do not* have the wide angle LEDs that you were reading about in the forums-- we haven't shipped any kits like that in a very long time, and we've exchanged most of those for narrow LED sets.  It is true that there is a bit more variation and width in the blue and green LEDs than we might like, but we've generally found it to be within what we expect from them.  However, thanks to this feedback, we're starting to look at a few other LED suppliers that might (hopefully) be able to give us a little better consistency in that regard. (BTW, the red LEDs in current-generation Bulbdial kits are actually Cree C503B-RANs, so you might want to skip swapping those, wbp.)

I'm not sure of the best way to ensure that the seconds/minutes hands are always distinguishable and readable.  (It's sometimes even a challenge with analog clocks!)   You might try playing with the relative intensities of the LEDs; that can help to bring up the contrast.  You might also consider aiming them a little bit differently.  If the blue (seconds) are aimed further out, you'll get a different character of shadow that doesn't overlap as much.

Windell Oskay

I see that I didn't answer the question about the rear projection clock face. 

 The standard clock face (included with the Bulbdial Clock kit) is made of opaque (non-see through) acrylic plastic, and has a white face with printed numbers on it. The gnomon (spike) protrudes up the same side that the numbers are printed on, and that face is installed facing towards the inside of the clock. When viewing the clock, you look through the three rings of LEDs to see the clock face and shadow hands cast by the LEDs and gnomon.

By contrast, the optional Rear Projection Clock Face is made of translucent and textured light-diffusing acrylic plastic. One side of the clock face is smooth, with printed numbers on it. Unlike with the regular clock face, the gnomon (spike) is attached on the "back" side of the clock face, protruding from the side without printed numbers. The clock face is installed with the gnomon pointing towards the inside of the clock (towards the LEDs), and the numbers on the outside of the clock. When viewing the clock, you look at the side with the clock that has the printed clock face, and see the shadow hands-- in rear projection --cast by the LEDs and gnomon upon that surface.