Author Topic: Instructable for IR pen  (Read 6422 times)

Offline UndCon

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on: April 29, 2008, 12:53:38 PM
Here are the instructions of how to make an IR pen like mine

Sorry for the quality of the pics - I used the cam on my Sony Ericsson P1
(A link to bigger pics is at the bottom of this post)

OK here we go...I do this on a brand new marker so there might be some amounts of color that drips out (be careful)
We need 1 marker, Faber Castell (#48 is my choice of color)

Bring a pair of pliers from your toolbox

Start by removing the felt tip with the pliers, pull straight out

As you can see its quite long, just about to come loose...

There we go...throw it in the bin (we wont use it again)

Grab the rear cap...

It comes of very easy - and we see a clear cap inside

Time to remove the clear cap - this one is glued and requires more force

I forced it sideways and it came out in 2 pieces, just grab the rest and pull them out as well...

Time for the reservoir - push the pliers into the "fluff" and pull out

That's about it - only 1 step left this time

Rinse out excess color from the pen...

And here it is in all its glory

Now this part is finished - I let the pen dry up completely inside as we are going to mount electronics inside.

To view larger images go to this URL:

In part II we will make the hole for the switch...(by knife) and adjust the hole for the IR led...(by drill bit)

As this is an Instructable I choose to lock the thread - answers can be posted in a separate thread and it can be found here:

« Last Edit: September 08, 2008, 06:33:27 AM by UndCon »

Offline UndCon

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Reply #1 on: May 02, 2008, 08:52:36 AM
Part II.

This time we will use a knife to carve our way thru the plastic housing.

I choose my old and trusted Swiss Army Knife – I keep the small blade as sharp as possible.(If you have a better tool and/or a better way to make the hole – go ahead)

This is the things we will work with.

Align the micro switch where we want it positioned.

Mark the plastic housing with the knife.

Make the markings a bit deeper with the knife as we are going to carve our way down…

The plastic housing is actually kind of soft to carve in, be careful not to hurt your fingers or let the blade go past the marking.

Measure with the micro switch how wide the hole is going to be and to keep track of the alignment.
This is the result of 5 minutes work.

Start tracing straight lines along the housing, Measure with micro switch to verify alignment.

Carefully make the markings deeper by repeating the process, but with a bit more force.

Really soon you will break through the housing and it is really easy to overdo and get out of bounds.
Cut through the remaining line and start on the other side, when done cut diagonally.

With some force applied it is easy to bend down the scrap in the center.
Clean up the edges with the knife.

A bit more carving to do along the sides makes the hole nice and tidy.
Another measure – and this time the micro switch actually fits, almost.

Now it is in the desired position. Time for measuring again.

This time it fits up to the mounting brackets that are a little bit wider than the rest of the body, perfect in other means.

Carved a bit more..tested again

Now we are close

With a little bit more force I could get it into the hole but it has to be pushed down even further.

That is the desired position.

This is how it looks like from the rear. Inside we can barely see the micro switch.

And here from the front, the shiny parts are the plates to solder on.

Even more and big pictures can be found at this URL

Questions and comments in this thread please:

In part III we will do the electronics.


« Last Edit: September 08, 2008, 06:36:15 AM by UndCon »

Offline UndCon

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Reply #2 on: September 08, 2008, 05:53:14 AM
Finally I got my soldering iron back so I could complete this IR-pen instructable.

Start by mounting the IR-diode into a helping hand or something that secures it and holds it firmly while soldering.

Here I cut the positive leg a bit shorter.

This spring assembly is going to fit snugly into the rear cap.

1 wire soldered to the positive side of the IR-led and some shrinking tube is applied - heat up gently with the soldering iron...

This tube is actually a bit big in diameter but as log as it stays in place it doesn't matter...

The 2nd lead to be used to connect the IR-led and the rear spring assembly.

This is the microswitch we are going to use. bend the rightmost leg around the corner...

Really nice - this is going to be the negative connector to the battery.

Solder a short lead to the microswitch...

...and protect again with some shrinking tube.

Now we are going to make sure the IR-led fits snugly into the front hole of the pen - use a drillbit or sharp knife.

Thread the wire from the microswitch through the pen housing and out at the tip - cut off excess wire but leave some to make assembly easier.

Here I show the length of the wire - but do not solder at this time... or you have to unsolder...

The lead must go through the housing...

Done! - push the IR-led back into place gently...

now check length of wire at the rear...

Solder the wire to the spring assembly.

I bent the sheet metal to form a springclip that holds the assembly in place.


Now the pen is almost done. Push the microswitch a bit more down into the housing.

That's nice

Can't wait? neither could I...

Really nice...

This is what's next...

Some scotch to hold the rear cap in place

Verify that it all works before glueing IR-led into position

Comparison bewtween this IR-led (Kemo) and a unknown one from an old TV-remote.

The Kemo is way better...

better images and a gallery:

Questions and comments in this thread please:

The next thing is my comparison between Kemo and Vishay.. I can tell you it's not as big difference as above but the Vishay is better by ~20% or so...
« Last Edit: September 08, 2008, 06:01:42 AM by UndCon »