Author Topic: prototype led mounting using a foam earplug  (Read 4699 times)

Offline lderooy

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on: March 28, 2008, 07:53:01 PM
I have a prototype pen that I am working with.  It is made from a whiteboard marker shell with an IR LED in the location where the whiteboard marker tip is normally.  I found an easy way to hold the LED in the pen is to use part of a foam earplug - the kind you roll in your fingers and then stick in your ear where it expands to block the sounds.  I rolled the foam around the "legs" of the LED and then placed it in the tip of the barrel.  When the foam expanded, it nicely held the LED in place.



Offline UndCon

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Reply #1 on: March 29, 2008, 03:40:06 AM
sounds promising - now you need a simple wayt to mount the switch and something to hold the battery (more earplugs)



Offline lderooy

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Reply #2 on: March 29, 2008, 09:23:16 AM
Actually I did use another earplug to mount the switch.  I have a small hole in side where the button of a microswitch sticks out.  It is held in place with an earplug.  By doing this, I can easily take it apart etc.

I still need a good way to mount a battery inside the marker case.  The single AA battery holder from Radio Shack does not fit inside....



Offline UndCon

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Reply #3 on: March 29, 2008, 12:54:56 PM
More earplugs :D

Can you get some pics for us so we see how simple it actually is ?

I dont know the diameter of the whiteboard-markers (I have to nick a few at work) - but Im quite sure ive seen something that would fit snugly inside...

I tried to bring some life into an old Psion Revo computer (PDA) and it is powered by 2 AAA batteries (Had to take it apart) but the AAAs are with wings for soldering...nice, Ill pop them into my GP-charger and see if there is any life left in there...

If not there are new ones readily available downtown...



Offline lderooy

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Reply #4 on: March 31, 2008, 11:16:28 AM
[NOTE: If you want to see the pictures you need to log onto the board]

Using a whiteboard marker housing (same as a highlighter housing).

Here are some pictures showing the foam earplug holding the switch and the LED in place.  I got the idea of a bigger hole to mount the switch from another post on this site (thanks!).

I also attached a quick diagram of a possibility of a tip switch.  I was thinking of mounting a microswitch to a round disk (red square) that fits inside the housing.  I will then "glue" a short plastic rod (red) to extend the mechanical switch to the end of the tip channel and "glue" the LED to the end of the plastic rod.  When you write, the LED touches the surface of the whiteboard and depresses the short plastic rod activating the switch.  On the backside of the switch is a resistor and battery.
« Last Edit: March 31, 2008, 11:59:54 AM by lderooy »