Wiimote Project

Wiimote Projects => Wiimote Interactive Whiteboard => Topic started by: jammin0 on May 10, 2011, 09:48:13 AM

Title: Pressure Sensitive Pen
Post by: jammin0 on May 10, 2011, 09:48:13 AM
I finally figured out how to make a decent pressure tip switch pen.  It only took me a year or so.  Just thought I would share with the forum since a few people were helping me on it way back when.

I have considered making these and selling them on ebay for $10 or $15 since it seems like the cheapest commercial ones are being sold for 2 or 3 times that much.  It was very frustrating for me because the pressure tip is so much more intuitive for hand writing and for my middle school students to use but I didn't like forking out so much money to buy one.  Finally got the one I like. :)
Title: Re: Pressure Sensitive Pen
Post by: JackieLee on May 10, 2011, 10:14:44 AM
Good luck
Title: Constructing Pressure Sensitive Pen
Post by: zainey on May 10, 2011, 09:25:14 PM

Could you please describe the method of your Wii Pen construction, to get the pressure sensitive function. According to your video, it seems to work well.

I have thought about some pressure sensitive tip methods, but they seem finicky and not well engineered.

One idea is for a 'zero-displacement' pressure sensitive tip.

Its possible to make a very simple, very low current transistor circuit which turns the IR LED on when the pressure tip contacts open.

In this way the pen activation pressure and required displacement to operate it can be made very low.

I have demonstrated such a test circuit on a breadboard, but I have not built it into a pen so far.

There is still some design potential left in the Wii pen.

Title: Re: Pressure Sensitive Pen
Post by: jammin0 on May 11, 2011, 08:39:56 AM
I'm working on an instructable with pictures.  Basically I am using a tact switch.  I too had really sketchy performance with spring methods.  It was just fine for mouse clicks but not reliable for handwriting or long drags.
Title: Re: Pressure Sensitive Pen
Post by: jammin0 on May 13, 2011, 05:28:51 PM
Ok, here's the instructable.
http://www.instructables.com/id/Pressure-Sensitive-Tip-IR-Pen/ (http://www.instructables.com/id/Pressure-Sensitive-Tip-IR-Pen/)

Feel free to ask if you have any questions.
Title: Re: Pressure Sensitive Pen
Post by: zainey on May 14, 2011, 03:35:55 AM

The pressure sensitive pen you have demonstrated is quite slick, and its simplicity and elegance shows a lot of thought.

I liked your Instructable as well. It seems Teachers makes great Salesmen as well.

Your pen can be distinguished from others on these points:

1. It is simple in concept with a linear assembly of components.

2. It is constructed from inexpensive and readily available components.

3. There are no unnecessary components, therefore saving cost, weight and labour.

    I liked the soldering of the battery terminals to the wires (never thought of that...)

4. The fitting up between the IR LED and Tactile switch is original too.

One small detail I could suggest an improvement.

Perhaps you could spiral the wires around the tactile button shaft when soldering to the legs of the IR LED. This would put less strain on the wires and solder joints, and means it would be less likely to break from long-term use.

Anyhow, great work, and good to see the bar being raised.