touchpad : alternative to using fingers

[pranav_j]

Hi,

I was trying to find a cheap solution to writing/sketching using
ordinary laptop touchpad. Is it possible? I mean, why doesn't touchpad
sense when I move some other object (eraser corner for ex) on it.

[pranav_j]

K. I found this http://www.eetimes.com/design/automotive-design/4009622/The-art-of-capacitive-touch-sensing

But it says nothing about a possibility of an alternative to human
skin (similar capacitance).

[This question may nt be related to WnCC, so sorry beforehand.]

[Antariksh Bothale]

Most touch-pads use capacitive touch technology http://en.wikipedia.org/wiki/Capacitive_sensing, as opposed to pressure-based resistive technology http://en.wikipedia.org/wiki/Resistive_touchscreen

If you have a look at the touch-screen phone available today, you will notice how a few come with a stylus while others don't. The stylus ones are pressure based, and people often tend to operate them with the tip of the their nail, while the ones without a stylus are capacitive and if you try touching them with the nail, they won't respond.

[Manav Kataria]

• Try using coin, it will work with your hand touching the coin. 
• Try using a battery it will work even without your hand touching it. 
  Disclaimer: The author takes no guarantee whatsoever of safe working of your touchpad post this operation! :p

Cheers! 

Manav

--
You received this message because you are subscribed to the Google
Group for the Web and Coding Club of IIT Bombay.
The website for the club is http://gymkhana.iitb.ac.in/~science.
To post to this group, send email to wncc...@googlegroups.com
To unsubscribe from this group, send email to
wncc_iitb+...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/wncc_iitb?hl=en_US?hl=en

[Ankush Jain]

I was looking for the same thing a couple of months ago. The answer I found is that u can use a anti-static conductive plastic (the plastics which appear to be shiny and have "keep away from children" warning :P). U can wrap a small piece of this plastic around the nib of a pen and use it as a stylus for your touchpad!

--
Ankush Jain

[pranav_j]

@All Thanks for replying!

@Ankush, cool, I'll try it.

[Uttam Sikaria]

I jus tried it..
doesnt work..
i hope i understood the right thing by anti-static plastic. i took a piece from the package of newly arrived dell motherboard

[Rachit Aggarwal]

I tried using metallic or any conducting objects on my capacitive touchscreen Phone.. it does work.. but the problem is that u need more surface area of the tip touching the screen for it to detect it..

I tried making a 4mm thick stylus using aluminium foil. It works well but causes scratches... so an alternative i found is to have a damp tissue on the aluminium foil stylus. it works gr8.

Also, on the contrary to earlier post of rejecting nail as non-sensitive to capacitive touch screen is wrong. You actually need to have more surface area of the nail to touch the screen.

There are some conducive stylus available in market which work well but all of them acquire more surface area on the screen. And this actually is a drawback of capacitive touchscreen over resistive touchscreen which are qualified more accurate.

As far i know, Tablet PCs have somewhat a combo of thermal and capacitive touch system. That is why they can be programed to avoid sensing hand touch and only use thermal stylus pens provided along with them.

Regards,

Rachit Aggarwal

First Year Undergraduate Student

Mechanical Engineering

IIT Bombay

[Rachit Aggarwal]

I observed one great thing in some of the HP laptops. The touch pad they use can be adjusted to sense only fingertip and nothing else at all. This is a very interesting feature as is help in avoiding accidental palm touch while typing.

So, I guess finger is most electrically sensitive part in periphery of the body.

Regards,

Rachit Aggarwal

First Year Undergraduate Student

Mechanical Engineering

IIT Bombay

[Karthik KSS]

I have just observed that sometimes the chords connecting a mouse to the laptop also causes the capacitive touch screen to react. How is this happening??

K S S Karthik

[sachin gautam]

actually touchpad uses our body  potential,i tried metallic object with my naked hand,it worked but when i tried with gloved or insulated hand using same metallic object it didn't worked,touchpad takes the advantage of our body,i really don't know what is so special with our body,sitting on insulated stool ,touch pad works with our finger so our body doesn't need to be at zero potential,so how potential comes in way???????

[Antariksh Bothale]

Your observation is correct, but I am skeptical about the conclusion you have drawn. As far as I see, the correction is software correction, i.e., the drivers detect stray palm flicks and do not send them to the operating system.

It is easy to test this - if you don't install the Synaptic drivers, your mouse works, but you get loads of stray flicks. Once you install the drivers, the palm flicks are ignored.

Look here http://www.techspot.com/drivers/driver/file/information/8293/

2010/10/10 Rachit Aggarwal <aggr...@gmail.com>

--
Antariksh Bothale
Institute Secretary for International Relations
4th Year, Mechanical Engineering
IIT Bombay

[Gaurav Meena]

1. Improved sizing (weight estimation) by using matlab code which was used in initial sizing
ye ppt me nahin aayega
Engine start, warm-up, taxi -
15 min at idle power,wf = (15/60 hr)*fuel consumption at ideal power,fuel cunsumtion at ideal power --- propulsion
Takeoff -1.devide takeoff in small segment and devide by the avg. velocity2. fuel burnt = CT(d/V)
Climb and accnprevious energy  methods of emperical formulaUsing avg. D/T by propulsioncruise height,V,g
Cruise and loiter-Emperical formulaR=range(L/D)cruise= AerodynamicsDescentEmperical formula = Cd0,W/S,K,V,roh,T/W,
Landing wi/wi-1=0.997

Required Parameter
Fuel comsuption rate = C, D/T,
L/D, Cd0, W/S, K, roh, V, T/W, E(endurance time for loiter)
Avg velocity and distance during take off segments,(done in initial sizing)

Sizing matrix plot
vary w/s (plus and minus)  20%
vary T/W (plus and minus)  20%
Each combination will produce diff. aeroplane the one with min. w0 and satisfying all the requirement will be final design (cruise, takeoff, climb, missed approach)
(By RDS, software from net and matlab code)



Carpet Plot (By RDS
Same but another representation of sizing matrix

Trade studies


Requirement trade studies
Cruise is our deciding factor of w/s  so change -
1. cruise speed, 
2. fuselage diameter or (aisle width) because it is very large
3. Second stage climb is our deciding factor of T/w so what variation does it can have


4. No trade studies for tail.

Aerodynamics (wing)
5. t/c and lamda
6. Airfoil shape and camber
7. A and lambda
                   
Structure
Materials - composite %
Payload




Sensitivity
aircraft operating cost and fuel price
aircraft operating cost and sfc

[Gaurav Meena]

sorry........................wrong thread :P