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I'm building a basic thermometer that displays the temperature on 4 seven segment LEDs. I want to put the circuit in a box with a clear plastic lid.

I'll mount the LEDs on the PCB around the other components, and fix this flat against the base of the box so the LEDs shine up through the clear plastic lid.

My question is how can I hide the electronics (i.e. the MCU, temp sensor, resistors, etc) but still be able to see the LED display, by some how darkening the clear plastic lid, and make it look more professional?

Alternatively, can you get enclosures with a translucent lid? I've searched but can't find any.

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  • \$\begingroup\$ All these suggestions are good, but I'll buck the trend and suggest.... nothing. Take pride in your project and the work, and keep the works so clean and pretty that you want to show it off. Exposed electronics are all the rage now. Embrace it! \$\endgroup\$ – user65586 Feb 27 '16 at 14:44
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You could mask off the section of the box above the 7-segment displays and then spray-paint the inside of the box to whatever color you like. If the alignment is correct, you'll just see the display.

Alternately (or additionally), take a piece of black paper or card stock and carefully cut out holes for the individual displays. Slide the paper over the PCB, and you'll be covering up your electronics. You could even add labels (or a logo) to the paper, if necessary.

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I'll try with a small square of those mirror films used to filter out sun rays from offices with lot of windows, or the black films used to darken car glasses.

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  • \$\begingroup\$ Yeah, I know what you mean.... do you know what this stuff is called? \$\endgroup\$ – BG100 Jan 13 '11 at 10:21
  • \$\begingroup\$ Unfortunately I don't know the name. Or, better, I know the name, but I'm italian, and "our" name can't help you to find it. :-) A colleague suggest to start from solutions.3m.com/wps/portal/3M/en_US/Window_Film/Solutions \$\endgroup\$ – Axeman Jan 13 '11 at 10:46
  • \$\begingroup\$ Thank you for this... I think this would be a really good solution, but the only problem is that I need a tiny amount of it, and I expect I would have to but lots of it. Thanks for the suggestion though. \$\endgroup\$ – BG100 Jan 13 '11 at 11:01
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    \$\begingroup\$ Try to ask to a car shop that installs those films. I usually can get small pieces for free as they are installation waste. \$\endgroup\$ – Axeman Jan 13 '11 at 11:21
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There are these mirror foils for smartphones: http://www.amazon.com/gp/search/ref=sr_nr_seeall_6?rh=k%3Amirror+foil%2Ci%3Amobile&keywords=mirror+foil&ie=UTF8&qid=1294916698

These could work!

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  • \$\begingroup\$ ummmm... maybe. I don't think I really want a mirror finish though... just dark. \$\endgroup\$ – BG100 Jan 13 '11 at 11:08
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This website has some tinted plastic normally used for windows and is pretty cheap.

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  • \$\begingroup\$ Thanks for this, but I'm in the UK, so I need to find somewhere that sells this stuff over here. I liked your first answer though, before you edited... I might try that! \$\endgroup\$ – BG100 Jan 14 '11 at 17:55
  • \$\begingroup\$ Spray paint & masking tape? Do it up! \$\endgroup\$ – Matt Williamson Jan 17 '11 at 17:31
  • \$\begingroup\$ Amazon will have it. \$\endgroup\$ – user65586 Feb 27 '16 at 14:43
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Could you attach a translucent sheet, like the thin Styrene sheet in the Sparkfun clock? "12ft GPS Wall Clock" tutorial http://www.sparkfun.com/tutorials/47 . Perhaps a few layers of HDPE milk jug would be adequately translucent?

Or even simpler: Could you use sandpaper to convert the clear plastic lid to a translucent plastic lid?

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Darkening will attenuate the indicator as well. Try a plastic foil appearing nearly same color with the indicator, to filter out other colors.

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Automotive shops sell a spray tint for plastic.. 1 layer gives you a slight tint, the more layers you use the darker the tint..

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