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Topic: Arduino WordClock (Read 18 times) previous topic - next topic

rmadhuram

Very nice!

Regards,
Raj

Stijn

Hey

Great work! I was more or less inspired by this post and by seeing one for real and started doing it myself as well. All is ready now but I'm facing serieus issues with the light: when using a sticker with a transparante background (so the letters are transparent) than the light is to strong and to much in one bundle (not enough spread) so you can't see the letters any more. Using a sticker with a white background makes it not transparent enough and my leds are almost not getting through... you only see it lighting up a bit... any hints how you handles this part?

Thanks!

Riva


All is ready now but I'm facing serieus issues with the light: when using a sticker with a transparante background (so the letters are transparent) than the light is to strong and to much in one bundle (not enough spread) so you can't see the letters any more. Using a sticker with a white background makes it not transparent enough and my leds are almost not getting through... you only see it lighting up a bit... any hints how you handles this part?


Hi Stijn,
Glad I could inspire someone  :D
After thinking of lots of possible ways to create the letter mask ranging from etching a copper clad PCB, printing on acetate, cutting letters out of sticky back plastic  and getting them laser cut out of card/plastic sheet I settled on a simple and cheap option of using a laser printer to print a reversed negative image on ordinary white printer paper. This piece of paper is cut to size then sandwiched between 2 bits of perspex. One is 3mm thick tinted that you lay the unprinted side of the paper on. Then you lay a 2mm thick clear sheet on top and tape/glue around the edges to keep it all together. I used a 2mm clear sheet because I had roughly calculated the light cone of the LED's would be the right size to illuminate the size of character printed on the paper when it's 2mm away without to much bleed into adjoining characters. This sort of worked when the display was dim but when it was bright I still got some bleed and had to resort to gluing black plastic straws between LED's. By luck more than judgement the printed paper worked very well and I did not have to bother messing around with different weight paper to get the desired effect.
You could try putting a ordinary bit of printer paper behind your transparency and see if it helps.

Stijn

Hey thanks for the fast response!

I started off with ordering venyl stickers which is rather expensive to 'test' so I feel stuck after ordering a few of them... the next one should be the right one. I'm working on a 50x50cm.

Here you can see the results so far:

Using a transparent sticker:


And a non transparent one:


I tried black 'light' paper between it, I tried white paper, I tried normal white paper, I tried so many things :) nothing works so far...

Riva

I must have been very lucky the first (and only) thing I tried worked for me.
Are you using MAX7219 chips or multiplexing with shift registers and are the LED's 5mm? I used 5mm high brightness white LED's and a couple of MAX7219 chips to keep the brightness up as multiplexing tends to dim the LED's.

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