Author Topic: tip-push IR-pen  (Read 6350 times)

Offline sts70nl

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on: June 30, 2008, 02:01:52 PM
As promised a guide on how to build a tip-push IR-pen.  The key component is an Edding Retract 11 Permanent Marker.

The beauty of the Edding Retract 11 Permanent Marker comes from being well over engineered.  Amazing how much effort went into designing and producing this marker.  However, for building a IR-pen it is great for it comes already with its own battery holder.

The complete materials list:

- 1x Edding Retract 11 Permanent Marker (for Dutch: found at Primera @ Ä2,70)
- 1x Metal ring 4 mm diameter
- 1x Screw with flat head (5mm 20mm)
- 1x IR-LED (5mm, 940 nm)
- 1x ball point spring
- A bit of tin foil
- 1 piece of wire (8-9 cm, thin; I used one of the four inner wires of a phone wire)
- Small bit of sticky tape (for insulation purpose on the IR-LED)

A soldering set is required, although soldering is limited to two joints (which Iím more than happy about for Iím not that good at it).

Most difficult thing I found, besides the soldering, was to remove a spring near the tip.  This took me a couple of minutes.

Initially I was a bit worried about getting the tip-push good enough. However, in hindsight, due to the design I came up with, the error margin in building/constructing is pretty big.  This was additionally proven when I built tip-push IR-pen number two and recorded mean while my actions and steps (see the YouTube video).

What you get, is an easy to fine-tune tip-push IR-pen with an internal battery holder. The IR-pen does have the look and feel of a white board marker.

[youtube]http://www.youtube.com/watch?v=85GS6OKCS3Y [/youtube]

Stefan





Offline apdewith

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Reply #1 on: June 30, 2008, 04:17:46 PM
Thanks for the video. It looks quite a job but the end result is awesome!
I have to say that the video does not reveal all the details of your activities.
I made my first prototype tip-push IR-pen myself but took quite a different approach.
For the IR-LED I used a LED spacer, drilled small holes at each side so that the LED leads come out at each side.
Finally I glued the spacer on a microswitch. All this I built in a blue Conrad USB-rechargeable LED-pocketlight.
(search for 'USB LED' on www.conrad.nl, it can easily be modified)
Working with a tip-push is really great compared to my push-button version using the same LED-pocketlight.



Offline sts70nl

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Reply #2 on: June 30, 2008, 11:53:23 PM
Thanks for the video. It looks quite a job but the end result is awesome!
I have to say that the video does not reveal all the details of your activities.
I made my first prototype tip-push IR-pen myself but took quite a different approach.
For the IR-LED I used a LED spacer, drilled small holes at each side so that the LED leads come out at each side.
Finally I glued the spacer on a microswitch. All this I built in a blue Conrad USB-rechargeable LED-pocketlight.
(search for 'USB LED' on www.conrad.nl, it can easily be modified)
Working with a tip-push is really great compared to my push-button version using the same LED-pocketlight.


If you need details on specific steps, let me know and I'll provide them in prose.

The most time consuming was to find a suitable pen (took me 5 shops and only stumbled on it by accident).  While reverse engineering the pen, the design was made.  Even the tip opening turned out to be exactly right for a 5mm IR-LED (the only one I had).  And fortunately due to the actual design of the pen, most of the work is simple (except the soldering part).  Then it was a matter of finding a flat tip screw and a ring (trip to the hardware store for I couldn't find any good at home).

The most difficult part was the soldering. Attaching the wire to the minus lead was difficult.  Initially trying to solder the other end of the wire directly on the stainless ring turned out to be impossible (with my first pen I tried for about half an hour before giving up).  A piece of folded tin foil with solder and the wire in it and then soldering it went pretty well (still took me 3 tries and about 10 minutes).

The most important part is the switch itself.  And this is done by the positive of the IR-LED that makes connection with a flat tip screw. Distancing the IR-LED positive from the screw when not pressed is done by a spring (just like in a ball-point).  Even most ball-point springs nicely fit over both the 5 mm IR-LED leads while fitting snugly against the back of the IR-LED.

The battery holder consists out of a part of the marker. The positive makes direct contact with the screw head.  The negative by means of a wire soldered on some folded tin foil.  This end is kept in place with a ring, part of the big spring and the end with a bit cut off.  The casing of the plastic holder, the big spring and the end are part of the original marker.

So the end conclusion is that most of the work was done by the Edding company by designing and producing such an elaborate marker.

Stefan



Offline apdewith

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Reply #3 on: July 01, 2008, 05:01:01 PM
I will order the marker (www.conrad.nl also sells it) and try to do what you did. Just because of the professional looking result!
But I will try to apply my approach using a spacer and a microswitch.
« Last Edit: July 01, 2008, 05:21:34 PM by apdewith »