Turning an optical mouse into an optical... pen! :3

[Avan]

Before I get an actual tablet, I'm thinking it might be a bit cheaper to use my soldering skills and love of messing with electronics to disassemble a dead optical mouse (bad USB wire), repair the wire, and modify it so that it would work sort of like a tablet: but for less than $5 (and without the tablet).

Basically all I'm doing is removing the buttons, scroll wheel, and optical device, and mounting them on a "pen" of sorts, then wiring them back to the original mouse's circuits which would in turn use the old (repaired) wire to connect to the computer's USB port... All I really need is a bunch of wire (which I have) and resin-core solder (which I also have - don't use non-resin core for electronics: it won't bond right: that stuff is meant for plumbing.)

[sniffswind]

if you get this to work, post the directions.  we, too, havve a dead optical mouse, and I could use the pen for some bits.

[Avan]

Here's what I'm experimenting with:
1) dead mouse (this is almost always because the connection wire will fatigue and break)
2) a whole lot of wire (50, but it can be a low gauge, actually its better if its lower)
3) prototyping circuit boards
4) perhaps some hinges (depending on how big the lens plate on the optical scanner is) - these allow it to operate nice and smoothly, but might drive the overall price up a dollar or two
5) the ability to solder

of course, I'll have to see how this works out first ^^ - it might not work out, but at least it's better to be safe and spend a few dollars on something fun than splurge immediately on a tablet.

[Nicholai]

I have an old optical mouse laying around here somewhere... (looks through abyss of computer junk)

Yah, it seems like the easiest way to do this would be to have the main board on a separate box, and just run wires to a small tube with the buttons and optical sensor. You would probably want to cut the bottom end of the tube at an angle, allowing you to rest it on a desk like a normal pen.
Dude, start posting progress shots right now! 

[Avan]

I have an old optical mouse laying around here somewhere... (looks through abyss of computer junk)

Yah, it seems like the easiest way to do this would be to have the main board on a separate box, and just run wires to a small tube with the buttons and optical sensor. You would probably want to cut the bottom end of the tube at an angle, allowing you to rest it on a desk like a normal pen.
Dude, start posting progress shots right now! 

First I need to find a reason to go grocery shopping near a radioshack store... I don't want to run all the way out there to grab a prototyping board worth a couple dollars... (I used to have one in the local shopping center, but they closed it when the economy tanked...)

[Avan]

I know, double post, but I kinda had a bad-news announcement - it's temporarily on hold, since the mouse turned out to be dead since the optical sensor is dead, not the wire... I'll need to scavenge around for another dead mouse with a working sensor...

[Yip]

Interesting idea, but how do you plan to handle the inherent differences between a pen and a mouse?

For example, with a pen/tablet the cursor will instantly move to the location corresponding to where the pen is placed. Whereas a mouse must be moved to the location.  If your optical pen works like an optical mouse, you'll have to move it along a surface to move the cursor (from my experience, optical mice don't work well if held up over the surface by just a tiny amount.)  Whereas normally with a pen, touching the surface is equivalent to left clicking.

Not trying to dissuade you from completing this project, just curious how you plan on handling these issues.

[Avan]

I plan for it to function just like a normal mouse... However, I will need to find a way to exactly position the light focusing mechanism so that it lands right under the lens for the sensor. That's probably the hardest part. The left-click switch I could have stick out by an extra millimeter or so from the bottom: enough so that if you don't apply much pressure, you can move the cursor, but if you push down, it will activate the "left click" function. Right-click will be a normal button, with the scroll wheel above that.

[Slylin]

Neat idea, you actually inspired me to try and make one too, it didn't work out too well because you need that led and that plastic part as a view point for the sensor unfortunately and I cant figure out how to add both the sensor and the led and the focuser to the tip of the pen so for now, I'm just going to have to make due with a mouse.

[Avan]

Neat idea, you actually inspired me to try and make one too, it didn't work out too well because you need that led and that plastic part as a view point for the sensor unfortunately and I cant figure out how to add both the sensor and the led and the focuser to the tip of the pen so for now, I'm just going to have to make due with a mouse.

Well, this can be achieved to sawing off the rest of the extra material around the lens (optional, but it makes it easier to use), and then attaching the remainders to the sensor and diode assembly (so it turns into something more of an 'L' shape, but close enough), and then making that hinge to the main pen assembly, the part you hold.
I found that it would be easier with an old ball type mouse, by taking the little position sensors and putting those on the base of the 'pen'.

[Ziel]

I'm really curious to know how this works out. You have to post some pics as the project moves along. And possibly make a demo video of it working when all's done?

This all reminds me of a project I've read about before. You can use the Wiimote's IR camera to track a simple IR LED placed into a pen shaft. There's lots of different versions of this sort of thing that people have done, some easier than others.

Here's a link to one version:
http://weblogg-ed.com/2007/the-wii-as-99-smartboard/

[Slylin]

You know what? I think I might actually just go and buy one Wii remote and try it with my screen. I would actually be able to draw on the computer. I'm going to the city in a couple days so I'm going to go try it, thanks.

[Slylin]

Haha, well I didn't own a wii so I just bought a controller, IR LEDs, a switch, a AA batter holder and a bluetooth usb. Turns out that only some bluetooths work and just my luck, I got one that doesn't work with it, don't buy a rocketfish one. So in about a week we are going back to the city so I will take it back and get one that does work. I will update when it works because Avan, this I think will be a good alternative to a tablet.

[Avan]

Don't you still need to buy some sort of sensor to detect position?

[Slylin]

Well, yes. The Infrared LED, AA battery holder, and the momentary push button was the "emitter". You know how you use a remote to turn on a TV? The TV has the infrared camera and the remote has the LED, well in a Wii remote it's the other way around so the remote has the camera and you need to make an IR pen, What you do is gut out a thick pen and solder the wires and stuff, (there are tutorials on youtube) and here is a picture of mine, and what you need: (warning, may be big pictures)

//EDIT: After my last edit the first link doesn't "link" just copy and paste it into browser.


This first one here is the IR Pen:  http://filesmelt.com/downloader/DSC_0020.JPG

This next one is How I soldered the IR LED (sorta): http://filesmelt.com/downloader/DSC_0022.JPG

This one is sorta a demonstration although I have to get a different bluetooth usb otherwise I would make a video: http://filesmelt.com/downloader/DSC_0023.JPG


Oh and I know I need to clean my screen but how do you clean lipchap off of it? That was my nephews doing, hes 3  

[Ziel]

I'm sure you've already done this, Slylin, but if not...

You can test to be sure the LED is functioning by having it on and looking at it with a digital camera. The camera can pick up the IR, and it just translates to what looks like a brightly lit spot on the preview screen.  You can do this with any IR remote if it isn't working to test and see if the LED is the problem. Also fun to use it to look at the Wii sensor bar. There's actually 5 IR LED's behind each of those black ends. Each one is put at a slightly different angle to maximize sensing area.

Back on topic a bit... can't wait for you to get a the bluetooth working so you can show a demo video.  I've only read about this before. Never actually seen it done.

[Slylin]

Well, I did do that test and for some reason its not working.. I soldered it all correctly I think. Does it matter if I have a 1.5v battery with a 1.2v LED? I soldered the short wire of the LED to the switch and the positive on the battery holder to the switch, then the negative wire to the long wire of the LED, if you know anything about electronics could you tell me what I did wrong? If all else fails I'll buy one off of ebay or use a remote to demonstrate but I will keep you updated.

[Ziel]

Well, you're in luck. I've actually tried making a wireless sensor bar for the wii, and thus have some good experience with IR LED's. Also studying electrical engineering. That could help, too.

You do have to be careful with LED's, as they do have a positive and negative lead. See here:
http://www.electronics2000.co.uk/pin-out/led.php

If you have the current going in the wrong direction, the LED will not work. I had that problem with my attempted sensor bar (turned out that my LED's weren't bright enough: if the room was completely dark it actually worked).  Easiest way to check is probably to switch around the battery.  Hopefully this is the only problem, and this simple switch will fix it.

You also should probably get a small resistor and throw it into the circuit. LED's have next to no resistance. And without resistance, you're practically just shorting out the battery. This will lead to low battery life, and the battery can actually get quite hot and could be a fire hazard (unlikely, but possible).  The resistor will provide the, well, resistance, needed to get the current moving safely. Do you happen to know any specs on the LED you bought? Most important would be the forward current. If you know the rated max forward current, you can calculate out what size resistor you need so the current is what you want.

[Slylin]

Thanks a bunch Ziel *husky hugs* flipping the battery worked, I will leave the battery out for now though so it doesn't get hot and when I go to the city for the bluetooth I will look into getting a resister. All it says is it's forward voltage and it says 1.2v it doesn't say anything about a max flow rate or anything so I would buy a 3v resister? Hehe, I'm not so hot with electrical currents.

[Avan]

Thanks a bunch Ziel *husky hugs* flipping the battery worked, I will leave the battery out for now though so it doesn't get hot and when I go to the city for the bluetooth I will look into getting a resister. All it says is it's forward voltage and it says 1.2v it doesn't say anything about a max flow rate or anything so I would buy a 3v resister? Hehe, I'm not so hot with electrical currents.

you mean .3v?

[Ziel]

Thanks a bunch Ziel *husky hugs* flipping the battery worked, I will leave the battery out for now though so it doesn't get hot and when I go to the city for the bluetooth I will look into getting a resister. All it says is it's forward voltage and it says 1.2v it doesn't say anything about a max flow rate or anything so I would buy a 3v resister? Hehe, I'm not so hot with electrical currents.

You mean Ohms (unit of resistance).
Where'd you buy the LED? And do you possibly know the part manufacturer? If not, I'll run a quick calculation assuming a common forward current. But you don't want to go too low, or else the LED won't be very bright.

Avan: You're kinda on the right track. We'll want to make sure that the resistor is dropping the voltage by at least .3 volts. But we also have to make sure it's putting the current at a good spot for the LED (i.e. it won't kill the LED prematurely).

[Slylin]

I bought the LED at radioshack and its a radioshack part if that answers your question.

[Ziel]

Yep. Checked the website, and it says it's rated to 100mA of forward current.

*runs to his calculator*

Okay. If my calculations are correct, you're gonna want to get these:
http://www.radioshack.com/product/index.jsp?productId=2062309

But I'm gonna complicate things even more for you. That's the smallest resistor value the store has, but you actually want smaller than that even. So I'm gonna have you connect two of them in parallel. This effectively halves the total resistance added (just trust me on that).

Quick circuits lesson:
To put two resistors in parallel, you need to have them both connected across the same gap in the wiring. That is, the two resistors will be right next to each other, rather than one following the other, in the circuit. Here's an example picture to show what I mean:
http://davebodnar.com/railway/LED_light_project/images/two_1000_ohm_parallel.JPG

See how the leads of the two resistors are soldered to the same wire?

This circuit should give you a little less than the maximum current of 100mA. But it will drop the voltage enough that the LED will be getting slightly less than 1.2V (which is good). Circuit should run safely for you, and the LED should still be plenty bright for the Wiimote's camera to pick up.

[Slylin]

Thanks a bunch. Okay I know how to solder it, now where do I solder it? on the battery wire that goes directly to the LED? or the LED to the switch? Battery wire to switch?

[Ziel]

Somewhere between the battery and the LED in the circuit. Sounds to me like you've got a wire going straight from battery + terminal to the LED. If this is the case, just cut that wire in the middle, and stick the resistors in there.

If you've got the switch already between the positive battery terminal and the LED, then it doesn't matter which side of the switch it goes on. Just that it's before the LED.