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Author Topic: Intuos4  (Read 10389 times)
random-jimmy
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« on: December 22, 2009, 01:14:38 PM »

Hi all! I'm new to the forums, and I decided to sign up so i could post build logs and to trawl your brains for knowledge. My plan is to fit a Dell Studio 1535 into an Intuos4 large. Both the screen and the active area are ver similar - the screen is slightly larger by about 4mm on all sides. By sticking the laptop right into the tablet I keep the portability of one device, negate any jitter problems (hopefully), and reduce cabling - I need a laptop for the portability offered.

I was just wondering if anyone here had any problems with the Intuos4 or with using not just laptops, but laptop screens. Or do you recommend I stick with the Intuos3, which has successfully been used in many builds, the least of these being the wei tablet.

Also, any helpful tips and suggestions. I'm a 17yo, but bright and I've got some very decent electronics and computer knowledge.
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monet
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« Reply #1 on: December 26, 2009, 08:31:30 AM »

Hi Jim

just tested 8.9" lcd on top of intuos4 medium, working, but not on the edge near the metal frame.
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random-jimmy
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« Reply #2 on: February 05, 2010, 01:21:39 AM »

yeah... there's a reason it's not working near the metal frame (i.e. shielding)

and big news for all: I have bought an intuos4 large and I have LOTS of good information.

First is that a 15.4" LCD screen is exactly the same size as the drawing surface (about 2mm error in that). This means that I will be able to just cut out around the drawing surface and get a neat, clean line (as the drawing surface is really an indent with a sticker in it).

Secondly, there is enough space in the intuos4 to fit the LCD inside without having to modify the case too much. There is some foam padding between the PCB and the metal reflector in the back of the case, and I'll see if I can remove that.

Thirdly, all the buttons and LCD's already in the intuos4 can be kept. Everything but the touch wheel button is mounted on a separate PCB screwed to the top of the case, not the bottom. The button in the touch wheel will need some padding to reach down to the sensor board, but it should work fine too.

If anybody wants detailed photos, I can upload them to dA but you will have to wait a few days until the internet quota is restored.

My only problems with the build will be actually screwing the laptop base onto the intuos4: I plan to use an entire laptop for the build. It is pretty heavy, so I may need to strengthen the tablet to hold the weight.
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random-jimmy
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« Reply #3 on: February 05, 2010, 01:24:00 AM »

Also, if anyone has any idea on how to start a build log, let me know: I couldn't see a "new post" link so I assume that it has been locked.
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cellofaan
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« Reply #4 on: February 05, 2010, 09:59:07 AM »

In order to start a new thread, you need to have at least 3 posts. You now have 2, so one more and you can start a build log. (guess your account was lost during the forum move too)

Laptop monitors aren't used that much since you need an lvds controller to drive them, and those aren't cheap. But since you'll be using the entire laptop, you won't have to buy the lvds controller. The wacom board is bigger than the screen, so depending on where you mount the laptop, you'll have to extend the cables between the monitor and the rest of the laptop.

Wei's build is a really really good one, so I'd try to copy his build as much as possible.

On removing the foam between the board and the metal plate, I wouldn't do that. The wacom works best with a specific distance between the plate and the board, which is why that foam is inbetween.

Good luck on your build!
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random-jimmy
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« Reply #5 on: February 05, 2010, 12:39:38 PM »

Hi! Thanks for the input. I didn't realise I had lost my account in the move (although I do remember having to re-register).

I did a bit of reading, and I have realised that removing the foam will be bad. However, on closer inspection, there is some ribbing beneath the foam that I can remove to gain an extra 2mm or so. It looks like I will have to install a plate to the Intuos4 base to make it strong enough to hold the laptop though. The plate will probably be a steel/plastic/steel material I have found scraps of that is exceptionally light, and yet can hold my weight. I just need to find a place to buy sheets of it.

Also, I have seen wei's build (and in fact it was his build that drew me into this dark mysterious world of DIY Cintiqs) however I will have a few improvements of my own to make to the design. One of the major ones is that I will simply keep the laptop base and screw that onto the Intuos4, rather than fabricating a new enclosure for it.

And I have already opened up my laptop (a long, long time ago back when I thought AS5 was cool) and I know that if I flip the monitor along the horizontal axis, instead of along vertical, I will have a decent 20cm worth of cable to play with (I hope that made sense). I am looking at just LED lighting the screen using SMD LED's - although I may have to find an alternate power source as I think my USB +5V is not off on standby.
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random-jimmy
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« Reply #6 on: February 05, 2010, 01:54:36 PM »

Update: All USB ports are ON on standby (meaning the laptop's backlight will stay on if I sleep the laptop, and I plan to do this quite a bit at uni). So for the moment I will try the current CCFL backlight, but if that causes problems perhaps I can make an LED adapter board to replace the CCFL inverter: hopefully the inverter uses a PWM control, and I can use this to drive the LED's via a transistor (and also retain the ability to change backlight brightness).
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bernard
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« Reply #7 on: February 06, 2010, 08:04:39 PM »

With all your electronic knowledge -- would you know of a way to "see" or "measure" these fields (or can you ask somebody that would know)?  First, from a frequency-wise standpoint (what to avoid using the same frequencies/harmonics) and then from a "force"/"spatial shape"/"direction" standpoint. If we could diagnose these things, I am sure it could help a lot.  In a LCD + Wacom combo, there is a lot fields going on...

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random-jimmy
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« Reply #8 on: February 07, 2010, 01:05:43 PM »

I could definitely try making a device to measure the field: it wouldnt be hard. Just what they call an LC tuned circuit (i.e. an inductor/coil - the L part - in parallel with a capacitor - the C part). However the antenna would be harder to make - and I haven't been to university yet, so I've missed out on a lot of that detailed knowledge.

It's just easier to take a monitor apart and sit it down on the Intuos4 at this point.
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bernard
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« Reply #9 on: February 09, 2010, 11:12:17 AM »

hum, I understand for the antenna -- and also to convert the "readings" that a "precise value".

A LC tuned circuit you said -- but wait a second -- Wacom pens - I think -- uses that type of stuff...

Could a re-use a pen's parts and start reading fields? These parts might be "perfect" since these are the ones that jitter is affecting!! 

Ok, so how can I "read" anything out of a LC circuit?  Can I hook my multimeter somewhere?  Do I absolutely need an oscilloscope to see the frequencies?
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random-jimmy
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« Reply #10 on: February 10, 2010, 01:13:08 PM »

I will most likely be very, very wrong here, but....

You could hook a multimeter up to the pen (directly across the coil i.e. at its two solder pads), and set the multimeter to read AC voltage. That *should* work. However, make sure the pen is dead first - there may be other components on the board which will affect the reading so you might have to completely destroy the pen. Also, I don't know how strong the reading will be (whether only a few mV or whether you might get some decent readings).

The only problem is that there may be other components on the board which will affect the reading (e.g. don't forget if the RF provides enough frequency to charge the pen, it uses the same coil as the "Send" antenna).

BTW if you plan on using this a lot, then solder wires directly across the coil, and perhaps but banana plugs on them. This means you can just plug it straight into your multimeter. Such plugs cost very little.
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bernard
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« Reply #11 on: February 11, 2010, 07:12:30 AM »

Speaking of the pen and your LC tuned circuitry...  The pen seems to essentially be a coil and then many combinations of capacitors+resistor loops hooked to that same coil. I mean this looks like a bunch of LCR circuits sharing the same coil. There is no other piece of electronic in the early pens.
My guess is that the tablet board try many frequencies that correspond to the various LCR circuits resonant frequency. Some of these circuits are only connected if you press the button on the pen (for example). I actually have no clue how this induction works and what to look for (we are fighting jitter here).

My pen is certainly not dead. I might be able to disconnect one of the coil wire to isolate from the rest, but wouldn't it be actually useful to use the current circuitry since they are already tuned to "resonate" at the frequency the wacom board uses.. no?

Is there a way to calculate the resonant frequencies by reading the values of the components using a simple multimeter and maths (i.e. without de-soldering anything?)  I am trying to make sense of all this...

thanks for answering.
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random-jimmy
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« Reply #12 on: February 11, 2010, 10:19:27 AM »

I am a little out of my depth here, but I will try as best I can....


If the capacitors have values marked on them, then it is possible to work out the resonant frequency. Google for an equation: I have never used it, but I know it must exist. (you will also need to know the inductance of the coil)

If there is no circuity on the board bar capacitors, switches and the coil, I would say you wouldn't need to modify it. Just solder wires to each end of the coil and away you go.

If you really don't want to ruin a pen, you might be able just to make your own large coil and measure the AC voltage/current across it (from my physics knowledge, it should be current, but voltage should work just as well). In saying that, I have just remembered I already have a large prewound coil at home that I can test stuff out on - it has about 40m worth of wire on it, so it should give a good result.
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bernard
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« Reply #13 on: February 12, 2010, 05:36:52 AM »

The pads for the coil are quite large, so, I should be able to solder wires without destroying the pen -- althought I might alter the pen tuning a little (?)   

I am looking for some online explanation on how the early wacom pen works (which I now think it is some sort of LRC) -- the circuit looks so simple!  Also, I think RFID use a very similar technology, although they use some sort of shifting register to feed bits onto the same carrier frequency instead of varying the frequency to make it resonate differently (if that is how it works!?).

Let me ask a "simpler" question to start this:

I have a toy for my kids here.  It is a train with 5 wagons.  But listen to this:  when you hook a wagon to the train, the locomotive (that has batteries) will detect which one is hooked in the "chain" (it talks and say which one is hooked).  I could not resist looking how it was done and opened a wagon.  Well, the wagons hooks are magnets -- but somehow there are 2 contacts so that is enough to make a "bus".  And inside the wagon there is a capacitor and a resistor in series hooked in parallel to the "bus" (if you follow what I mean)  The locomotive seems to be able to "read" capacitor/resistor is present.  This very much look like the early wacom pens btw (just that the locomotive the pen-tip "Coil"). Do you have an explanation for the train?  How can it "read" which one is present?

ASCII-ART schema for two wagons attached to the locomotive -- the bus has 2 wires (the horizontal lines)

   
        W1              W2
-------------------------------
        |                  |
        =  C1            =  C2
        |                  |
        Z  R1            Z  R2
        |                  |
-------------------------------

I assume the C/R values differ for each of the 5 wagons.

How does it work??
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random-jimmy
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« Reply #14 on: February 13, 2010, 11:40:53 AM »

From what I understand, the newer tablets actually work by first "charging" the pen, and then reading back the into from it via a digital signal. This is exactly the same way RFID tags work: first they are charged via an electromagnetic coupling with the coils of the reader, and then they transmit information - their ID, or balances for toll cards - via the coil to the reader.

However, I do not know how the older tablets work. Perhaps they work in a similar matter: first a large capacitor in the pen is "charged", and then it discharges through an RC oscillator (the wagons in your train analogy). Depending on the resistor or capacitor value (selected via a button, or in the case of the pen tip, the variable capacitor), a different frequency will be produced, which is sent through the coil back to the tablet. By identifying the frequency, the tablet can tell what button is pressed, and by identifying which coils register the frequency strongest, the position of the cursor can be determined.

The only difference between the old and new technology is probably the progression to a digital signal (like RFID) from the analogue FM signal (in terms of how the data is represented)

Looking at the pictures of the pen you provided, there is a large SMD cap mounted on the board, however I can't see one in the mouse... but still, that is how I think the pen/mouse works.
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