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Topics - skimmer

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IR Pens / TSAL6100 questions
« on: December 06, 2009, 08:30:29 PM »
I'm wondering if anyone knows more information about LEDs.  I have two questions.
First, I noticed that the TSAL6400 has a radiant intensity of 40 mW/Sr.  I'm assuming that this is an indication of how bright the light is.  The TSAL6100 has a smaller dispersion angle than the 6400 (10o instead of 25o) but has a radiant intensity of 130 mW/Sr.  This should make it a lot brighter, right?  I've also read that a lot of the IR light that the wiimote picks up is reflected off the white board surface ... so again, the brighter the better, right?  All other specifications between the two seem the same.   
Secondly, if a battery starts to become underpowered because the voltage falls too low, does the LED cease to work altogether, or does it just get dimmer and dimmer like an incandescent light bulb does?  If it does get dimmer, would the 6100 with a higher radiant intensity last longer on a lower voltage than the 6400?  In other words, say the voltage hits 1.1 V (or whatever voltage is too low) and the IR signal from the 6400 is now too low to be registered by the wiimote.  Would the 6100 still be bright enough at 1.1 V because it has a higher "native" radiant intensity?  I would really love to get the most out of my 1.2 V NiMH rechargeable battery.

I've been toying with the idea of marketing the tide-to-go IR pen.  I was just wondering if there were any legal issues with the pen using Tide-to-Go parts for the pen.  I've noticed that other pens use parts of existing products, such as pen casings.  Is this a non-issue, or are we all waiting for some corporation to come raining down on our parade?


IR Pens / video showing pressure-tip pen in action
« on: March 13, 2009, 10:11:59 PM »
Hello everyone,

I've been meaning to post a video of the Tide-to-go pressure tip pen for quite some time now.  I've finally gotten around to it. 

When I made my first push button pen, writing was quite a challenge.  To constantly push a button was too fidgety - the strokes had to be very deliberate and the writing was very slow.  Handwriting was definitely easier than printing, since you could keep the button pressed continually, but printing, writing formulas, chemical equations, and numbers etc... was quite slow.  I went from being very excited about an interactive whiteboard to being doubtful about its usefulness to me as an actual whiteboard.  To be able to use an interactive whiteboard in the classroom on a regular basis, I needed to be able write much, much faster on it. 

The solution of course was a pressure tip pen.  After many iterations,  I finally came up with one that writes beautifully - the Tide-to-go pressure tip pen.  It feels very much like writing with a regular white board marker.

The main reason for showing these clips is so that others who have tried the wii whiteboard but found it to be more of a novelty and too impractical to write with on a regular basis can see that it is very possible with the right pen.

The first clip shows the pen's weight and how little force it takes to activate the LED.  I've read some posts of pens requiring "only" 50 or 100 g of force to activate the pen.  My pen weighs about 22 g and the tip will light up at maybe 5 g - it's hard to tell exactly by looking at the balance.  The weight of the pen itself is definitely enough to activate the pen.  Naturally, the less force the better - writing is very natural and easy feeling and there is less abrasion on the LED.

The second clip shows some actual writing.  I teach chemistry, so I've used a chemistry example.  I hope the ease of writing comes across in the clip.  I'm writing on a 1/8" wood fiber board with a melamine surface which has been taped onto a blackboard.  I find it to be a pretty good surface to write on.  I've found that if the board is too smooth or glossy (eg. plexiglass, glass, plastic, smooth painted surface like a table or wall, varnished surface) the LED rubs against it with a lot of friction (it's very noticeable if you rub the led against the surface quickly).  I think a  lightly textured surface works much better.

If you want to actually write with the wiiboard, not just doodle, or write the odd word - but write for an entire lesson : notes, examples, diagrams, etc... you need a good pressure-tip pen.  I'm still on the hunt for a pen tube (other than the tide-to-go tube) which will accommodate a AA battery but still fits the tide-to-go tip.  If anyone finds one, please let me know.


IR Pens / improved pressure-tip pen
« on: February 08, 2009, 09:41:13 PM »
Hello everyone,

I've improved upon the tide-to-go pressure pen.
I'm assuming that you've already read about it, so if you haven't you should have a quick glance at the post:
The old pen was a bit fiddly with the assembly - the wires would interfere with the spring mechanism.
Now the wire IS the spring mechanism.  The pen also now uses the entire tide-to-go pen and an AAA battery.
I've included some photos of the pen and a short video of the spring mechanism and the working pen.
I'll try to post a video of the pen in actual action soon, so you can get a sense of how well it writes.
I hope the video shows how sensitive the pen is - others pens that I've seen look like you have to push down really hard.

IR Pens / IDEA for a pressure sensitive IR pen
« on: January 18, 2009, 03:23:05 PM »

I learned about this whole wii whiteboard idea just a little while ago and have been busy trying to make an IR pen ever since.  I first made a normal push-button pen and was excited to try it out.  I discovered that it was very difficult to write/print quickly with it (and my wife was absolutely disastrous at it).  So I tried to make a pressure sensitive pen.  The pressure sensitive pen is SO much easier to write quickly with (I am a teacher and am hoping to use this as a whiteboard in the classroom).  This pen is also very sensitive - ie. you don't have to press hard at all, and it feels very much like writing with an actual whiteboard marker on a whiteboard.

This website has been so helpful in guiding me, I thought I would contribute what I came up with.
The key to my pressure sensitive pen is a stain remover pen (Tide-To-Go) which already comes with pressure sensitive tip.  I've included a diagram with some comments.

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