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1  Screen Tablet malarky / Build Logs / Re: The MONARCH Build on: February 15, 2008, 01:06:27 PM
There is a fantastic article on building a router table in the April 2005 issue of Popular Woodworking (http://www.fwmagazines.com/product/22/1).  It may not be justified, though, if you aren't planning on doing a significant amount of routing work.  I do woodworking as a hobby and I only bought the cheapest router bits that I could find.  You'll may have some issues with tear-out, but that shouldn't happen until the bit dulls.  The bits will dull faster, but if you don't use that bit very often it really won't dull that quickly.  The only quality issue I've had was I did have a bit snap, but that was because I was trying to plow out the wood too quickly.  If you are just planning on using the bit on one or two relatively small projects, you can probably get by just fine with a cheap bit.
2  Screen Tablet malarky / Build Logs / Re: The MONARCH Build on: February 12, 2008, 08:58:07 PM
MDF and wood isn't temperature sensitive so much as it is humidity sensitive.  As humidity levels rise, the wood will absorb more and more moisture and expand.  That's why some doors stick in the summer but swing freely in the winter.  Sealing the wood, either with paint or some other sealer like polyurethane, will also help to overcome moisture problems.

A common trick for attaching table tops is to use figure eight fasteners.  One screw goes through the figure eight into the table base and the other goes into the table top.  The figure eight allows the top to expand independent of the base without splitting the wood. 

Other tips:  If you want to build something out of hardwood, rift or quarter sawn wood is more stable than plane sawn wood.  Basically, get the wood with the straightest grain that you can find.  It will tend to expand perpendicular to the grain but be very stable along the other axis and is less likely to cup bow or warp. 

Plywood is generally much more stable than hardwood, so a good candidate for case material is a hardwood plywood (NOT construction plywood).  This is likely what your kitchen cabinets are made of and carpenters generally make jigs out of birch plywood because it is so stable and repeatability is important in plywood.  If your local hardware store doesn't have any, you can get baltic birch plywood from Rockler http://www.rockler.com/product.cfm?page=846
3  Screen Tablet malarky / Build Logs / Re: Robcat2075 build log on: February 08, 2007, 10:21:24 PM
I can comisserate with you as you and I were using the same monitor and I had the exact same thing happen to my monitor. The FFCs connecting the top of the screen just kind of broke off. I could press some of them down and get the monitor to kind of display a picture, but for the most part it was just completely dead.

On a side note, I did find that placing a metal shield between the top controller board and my Aiptek tablet did elimitate at least most if not all of the jitter. I just used the metal shield that was inside the back of the monitor. It was very thin, but seemed to provide enough protection to shield whatever was causing jitter.
4  Screen Tablet malarky / Build Logs / Re: fpevul88's build log on: January 28, 2007, 02:08:49 AM
That's probably 20 mA per LED, so it's likely that you'll draw 360 mA if you are using 18 LEDs (from an earlier post of yours). The resisters will dissipate some current as well, I believe (is that right?). Most LEDs I've seen draw between 20 and 25 mA unless you get some super bright LEDs, so plan a power budget between 360 and 450 mA. A 500 mA power supply would probably be good just to be safe. I wish I knew how much current a backlight inverter drew so that we could try to determine how much current has been freed up by unhooking the backlight.
5  Screen Tablet malarky / Build Logs / Re: fpevul88's build log on: January 26, 2007, 03:34:57 PM
Yup, red + and black - (http://en.wikipedia.org/wiki/USB#USB_signaling). USB provides as much as 500 mA at 5 volts, though it is only required to provide 100 mA unless the device requests more current.
6  Screen Tablet malarky / Build Logs / Disaster on: January 26, 2007, 05:49:13 AM
Well, I've been kind of skulking about for a while here. After some small amount of hastle, my monitor arrived. I disected it and got to much the same point that Robcat got with his build (he and I have been chasing the same config. Same monitor and same Aiptek tablet). Robcat has done such a splendid job documenting his build that I haven't felt the need to add much.

My FFC cable extension came today. I ordered mine from lumenlab and hadn't considered that the length of the extension would be an issue. Indeed it is. The 6" extension just reaches between the two connectors. I hooked them up and then powered on the monitor to see if the extension worked. The monitor wasn't displaying properly, so I tried moving everything back to its original orientation and removing the FFC extension and just plugging the FFC directly into its ZIF socket. It was while I was moving things around there that I noticed one of the FFCs leading from the LCD controller circuitry to the LCD itself had torn free from its mounts. Several others suffered a similar fate.

I suspect that the tearing happened as I was unfolding the circuit boards. This monitor is rather old and things have gotten kind of brittle. This was quite the blow, though, as I've now killed two displays in the pursuit of the integrated tablet. I'm not really sure right now just what I'm going to do. I'd still like to continue with the build, but I may be a bit more picky about which monitor I purchase. I'd like to avoid FFC issues alltogether and I'd also like to get a monitor that's a bit newer than the IBM 9511 I've got now.

On other fronts, I've played around with LEDs a bit and believe that they are indeed a viable baclight alternative. I'm excited about their potential. The pictures included below use 3 5 mm LEDs as the backlight. The LEDs are wired within a 17 mm wide area. I'd like to wire up about 50 LEDs, which should cover the 27 cm monitor width quite nicely. Even though my monitor is now dead, I may still use its backlight slab for LED backlight experiments.
7  Screen Tablet malarky / Build Logs / Re: fpevul88's build log on: January 25, 2007, 10:01:38 PM
That's really going to be a function of the current draw of your LEDs. Also, if you plan on running your monitor and LEDs off the same power supply, then you need to sum up the current draw of both the monitor and the LEDs.

For instance, if you are using 10 LEDs that draw 25 mA each, then you need a power supply that can provide at least 10*25 = 250 mA. If your monitor says that it needs 3A, then you need to add that in to show that you need a total 3.25 A power supply. It's always nice to have a larger power supply than you think you need in order to handle peak current draw as well. If you only need 3.25 A, I'd shoot for a 3.5 A power supply or bigger.

The amperage doesn't matter so long as it is MORE than the sum of the current requirements of all your devices.

If you're current draw is low enough, you could even draw the power from USB.
8  Screen Tablet malarky / Design issues / Re: No backlight at all? on: January 25, 2007, 06:47:07 PM
Not even knowing much of the technical details of the retroflective stuff, I'm skeptical that a no-backlight solution would really work. Nintendo did that with their GameBoys for years. They were awful unless you were in an extremely well lit area. I really think that there needs to be some backlight, no matter how dim it is it should be better than no backlight at all.
9  Screen Tablet malarky / Build Logs / Re: fpevul88's build log on: January 23, 2007, 05:59:54 PM
Here's a handy wizard that will help you design your LED circuit: http://led.linear1.org/led.wiz

The wizard accepts the source power supply voltage, the forward voltage of the LEDs, and the current draw of each LED as well and outputs a wiring diagram that tells you how many LEDs should be connected together, the resisters that you should use, etc. Pretty neat.
10  Screen Tablet malarky / Design issues / Re: I May Be Dumb But on: January 22, 2007, 05:29:02 PM
Poked around the house and found that my Nintendo GameCube powersupply is 3.25 amps at 12v. Not too shabby. You should be able to get one rather cheaply from a used game store. Ebay has them for $10 USD plus shipping, so they will hopefully be similar at the store.
11  Screen Tablet malarky / Heyaaaalpppp / Re: Just about to Start on: January 22, 2007, 03:31:19 AM
Hey Chems. It is desirable to get a monitor with an external power supply because the power supplies can cause significant amounts of interference in the tablet. This results in the pen being jerky or simply unresponsive all together. It is also nice in that it makes the combined tablet just a bit lighter, but that is really a minor side issue.

Something else to consider is that some monitors have FFC issues. An FFC is a flexible flat cable. Often times the circuit boards in the monitor are connected by quite short cables that don't allow for the tablet to be inserted. If your monitor has a short FFC, you may need to order an FFC extension. I ordered mine from lumenlab, but I believe that DIY Beamer is located somewhere in Europe and may be more appropriate if you live on that side of the world. Unfortunately, you may not know whether you need an FFC or even which FFC you need until you start taking your monitor appart. If you snoop through the Lumenlab forums you should find a list of monitors with 'FFC issues' (i.e. short FFCs). If someone else here has a link to such a post, please include it!

As for the foam, I am actually not planning on using it, but it was inserted between the tablet grid itself and the top of the tablet. I'll defer to Drewid on where he inserted it in his build.
12  Screen Tablet malarky / Build Logs / Re: fpevul88's build log on: January 20, 2007, 05:29:28 PM
I've tried a number of different things and had no luck. I've even tried a metal shield. The problem with a metal shield, though, is how do you shield just the light, but not the tablet grid? I've even looked at 3rd party backlights (see my build log). I've pretty much moved to the point where I'm going to look at LED backlights.

Also, I've found that the controller circuitry on my LCD causes interference. That, fortunately, can be shielded easily using just some sheet metal. It doesn't shield the grid from the pen, though, as all of the circuitry is above the top of the LCD.
13  Screen Tablet malarky / Build Logs / Re: fpevul88's build log on: January 19, 2007, 08:25:24 PM
The two springs on the Aiptek need to be connected to the shield. I believe this is where they get their ground (or earth, for those of you on the other side of the pond). Connecting them does make quite a difference. The shield itself, though, will only shield magnetism if it is ferrous (iron, steel, etc.). i.e. if you can stick a magnet on it, it will help to redirect the magnetic field away from the tablet.
14  Screen Tablet malarky / Design issues / Re: adesso or aiptek on: January 05, 2007, 10:44:35 PM
Good luck with Aiptek's support. I sent them an email inquiry about jittery lines about a day or two after I got my tablet (before Christmas) and still haven't heard anything back from them. I did have very good luck when I called them on the phone, though, but that was just a shipping question. No idea how long the hold would be for a technical question.
15  Screen Tablet malarky / Design issues / Re: LED backlight? on: January 04, 2007, 04:28:48 PM
LED backlit laptops are expected to ship in 2007. http://www.digitimes.com/news/a20070103PD210.html
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