Sunday, March 1, 2009

Power Switch and LED Indicators : Revisited

Finally got around to building (most) of the front panel LED indicators and switch assembly. There have been some overall design changes since the initial prototype was developed.

The overall external view will be as follows - with the internals build much as outlined previously. Note that the power LED no longer sits within the button.



I figured the long oval LED shapes would be easier to give an even LED light...

Starting with the LED arrangements, I started drilling and cutting the long oval holes...



These pieces are to be layered together...



The piece with the open ends sits away from the main face plate. The idea of the open ended bit is for allowing the LEDs and wires to be inserted (note that I changed this a little - see later pictures - to allow the LEDs to be inserted from one end). With the LEDs inserted, it looks something like this



And with the LEDs iluminated, and the lights turned down, like this.



You can see as usual, the RED LED is significantly brighter than the green one. When put behind a larger piece of perspex, you get the following effect of the LEDs.



The red is clearly brighter, and has a fairly irregular, spreadout shape. The green is pretty dull in comparison. There are no clear edges to the LED shapes either. Which were all the same kinds of problems that I ran into before.
Anyway - resorted to aluminum foil again to try and improve things a little.

Firstly using foil to define better the shape of the long ovals...



which when you put the perspex back in front, does tend to give a slightly more regular shape to the LED light.



The green LED is still however very dull in comparison to the red LED. Note that the scissors are there to help the camera to focus - otherwise it is all just a blur.

To help improve the greens LEDs appearance, I tried using Aluminum foil behind the green LED enclosure - as a reflector. The results seems to provide an improvement (wishful thinking ??).




The green LED is a little duller than the red, however as the red is only on in flashes for the HDD access - not too much of a problem.

One point to notice, when the LEDs are not illuminated, you can actually see the cut-away oval behind the perspex sheet as a blurry shadow :-( Oh well - not a huge problem.



Now all of these LED and button things need to be attached to a piece of perspex that is to be screwed into place later in the case. The basic layout of these pieces is as follows.



All the pieces will be attached to this backing plate, which screws into some mounting strips glued to the inside of the main case perspex. The mounting strips are made out of two strips of perspex with threaded nuts embedded in them.





Note that it was a strage convoluted process for ensuring the LED ovals aligned with the center line of the front panel :-)

For attaching the on/off button, I used the same method as in the initial prototype - but with slightly more robust pieces of perspex. The cut up pieces and hole are shown here.



Next point was the push button and the hole for it. Some Google-ing showed that potentially a tile drill bit could be used to drill into perspex to get a nice even round hole. Bought the following 28 mm diameter drill at the local hardware store, and started playing around with it.



To start off on a blank sheet of perspex, you need to angle the drill and get it started on one side - then you can switch it back to a 90 degree angle and drill normally. You can use this method to give you a template for cutting into the real perspex piece of work.



With the template clamped in place, I started drilling the real piece - from the outside in. Seemed to have a nicer edge on the side from which you drill from. Note that one advantage of using this tile drill, which does not have a central drill bit to locate the hole for drilling, is that the central core of the hole will be used as the actual button piece later. There is only around a 1 mm gap between the hole and the central button piece !!



You need to drill relatively slowly for the hole, otherwise the pieces heat up. It can leave a little lip on the central core piece that you are drilling out. Another issues is that the central core gets stuck in the drill bit - I am still looking for a better way to remove it without inflicting some small scratches on it.

The finished hole.



Now back to assembling all of the pieces...

Attaching the LEDs and the switch in place...


(note I will use a cable tie when finally fixing things in place... and the LED alignment will be tweaked - as there will be aluminum foil around)

and from the back view of this add-on plate, showing how the switch is mounted...



This whole assembly gets screwed onto the mounting strips glued to the inside of the case.



Rotating forward slightly you can see how it aligns with the hole drilled from the front of the case.



This is how the whole thing looks when assembled...



Note that the inner button piece has not been glued in place - still wanting to drill a 'perfect' piece for this :-)
Also note how you can see the internal infrastructure through the perspex - to be sorted when lined with aluminum foil or equivalent.

And the final look with LEDs illuminated (without the foil still - the topic of another post)




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