Monday, June 23, 2008

My Wiimote Whiteboard and Light Pen

By now, unless you have been living in a deep dark hole of non-geekdom, you've probably heard of Johnny Lee's incredible experiments with the wii remote or "wiimote". Basically, he has discovered a way to turn a $30 wii remote and a small light pen made at home in to a multi-touch whiteboard technology that can be adapted to any surface. I had to give it a try.

First I needed a wii remote, because I don't currently own a wii. I found one on eBay for $29.98 shipped. Next I needed the components for my light pen. A trip to Radioshack and a local art supply store took care of that. It's funny to see how Radioshack employees react when you ask them how to calculate the right resistor for your LED.

The formula for that btw is:

R = (V1 - V2)/I

V1 = The voltage of the battery
V2 = The voltage rating of the resistor
I = The current of the resistor in Amps

Here are the components I used from Radioshack. The cost is higher than if I would to have ordered from a somewhere else, but for a prototype it's nice to just be able to go down the street:

Lithium 3V CR1220 (230-0188) $5.49 (probably over kill)
5mm IR LED 940nm (276-0143) $1.99
P/B Switch SPST (275-1547) $0.87 (I bought a pack of 4 at $3.49)
10OHM resistor (271-1301) $0.20 (I bought a pack of 5 at $0.99)

For the casing, I saw Johnny Lee using a dry erase marker at his TED talk and realized you could fit all the components inside as opposed to using a Bic pen and needing an external power supply. However, dry erase markers are expensive. I was about to buy a back of 3 for about 8 bucks when I found hidden in another section the "Mr. Sketch" scented markers. They are the exact same shape as dry erase markers and much cheaper. I bought a pack of 8 for $5.49.

The total cost of my light pen: $9.22
The total cost for the entire project: $39.20

Cost of a standard electronic whiteboard: $2,000

Now I needed the software to run my whiteboard. I have a mac and Johnny's Wiimote Whiteboard software is written in C# for Windows. Luckily some smart people ported the software to java and also created an OS X native version. I used the OS X version.

The light pen was constructed with lots of trial, error, solder, and electrical tape. You can see in the video demo, I taped the contacts to the battery and later just shoved it in and recapped the bottom of the pen.

One cool thing I learned while surfing discussions about the light pen is that you can test your IR pen using a camera phone. The camera phone will pick up inferred light. You can see this in the video of my light pen.

Here is my light pen up close:

Here is a demo of the whole set up:


Rshacker said...

You write "It's funny to see how Radioshack employees react when you ask them how to calculate the right resistor for your LED."

Actually, it's funny to see customers that ask our employee's these sort of questions.

RadioShack does not train it's employees to know this information.

It's like asking your car salesman about the transmission in your car, why does it go thunk ? He won't know.

You are fast to ridicule an employee's lack of knowledge of a product that the company does not provide training on.

There is a reason there is no training, those little parts do not provide a large profit for the company.

No employee in there right mind is going to waste time watching a customer selecting LEDs, diodes, and so on, only to lose a sale to another customer that will make him money.

Yes, it's all about money. As an employee, we get paid to sell, and make a commission on what we sell. (as long as we sell over a certain amount per week)

We, as employee's make nothing on those little parts what so ever.

Hope this will help you & your buddys understand why we do not provide you the information you are requesting.

We are not required to, and don't have the time to not make money.

We have to make a living.

PC Maho said...

@ rshacker

Thank you for your comment. Let me explain.

As an ex RadioShack employee I know all too well about the lack of good training in most of the items in the store.

The problem with Radioshack is a huge lack of specialization. This is expected with a commission based system and not all that uncommon.

However, they do sell the stuff (and I really hope they never stop, I was in fact surprised they still do)

When I asked if the employee knew how to calculate the size of the resistor I didn't expect him to know and I wasn't being demanding. I just went out on a limb and asked because hey, they do sell it and (at least when I was working there) there was a training manual for Parts, no one read it though.

Also, you should know it didn't always used to be that way. RadioShack used to hire really smart people who knew a lot about electronics as a whole. RadioShack used to be the #1 destination for hobbyists. Some years back they made a decision to move away from that and compete with Circuit City and what not. It worked out well for them.

In conclusion, me and my buddies will stop asking silly questions, RadioShack: "You've got questions, We've got cell phones".

And I hope you have figured out that RadioShack seriously underpays their employees. Take a look at how much you're making vs. how much work you do. Other places have stock people, just saying....