I have comprehensive and practical knowledge of resistive and theoretical knowledge of capacitive touch pads. I was wondering if there are velocity sensitive touch pads out there.

I'm guessing if they do exist these pads will be impossible to recreate in home based workshop - kind of like the capacitive touch pads (or are those feasible?)

Just want your input, if it is not out there, I want to start a constructive discussion as how to it could be built.

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transistance is futile...

 

Just a thought: would this be possible by implementing a piezzo array below the capacitive/resistive layers? Can piezzos be built small and thin enough?

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Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Can you explain the term "velocity sensitive touch pads"?
Is this the same as pressure sensitive touch pads?

Thanks,

 

Not sure, i don't think so though.. It should involve some kind of acceleration sensor the way I'm thinking. Kind of like how modern synthesizers' keys.

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transistance is futile...

 

..for what I know synthesizer keyboards determine velocity value (MIDI information) by sensing 2 switches. The closure time difference between the 2 switches determine the velocity (volume) value. Is this what your are looking for?

Is there a synthesizer that used an acceleration sensor?

 

please i have a dell laptop pentum m d600 and it is not charging the battery, but the computer is working properly. the only problem i am facing now is that is it not charging the battery, i need a solution and the laptop diagram.

 

Hello ikennaobi,

Please start new threads when you want to start a discussion. This thread is about something else entirely. Posting an off-topic question in someone else's thread is known as "thread hijacking" and just confuses things.

At a glance, it sounds like your laptop battery has just gotten too tired to hold a charge anymore. As far as I know the only solution is to buy a new battery.


Torben

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2 switches make more sense, but I'm guessing it is also the reason behind having cheaper and more expensive synthesizer keyboards possibly. Since having individual accelerometers in my opinion will give better continuous data, and will cost a lot more.

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transistance is futile...

 

I don't think any do such a crazy thing - two switches works perfectly - I don't see as accelerometers would improve it, quite the opposite probably as it couldn't detect a held down key.

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I've heard of the two switches thing and others which use FSR (the two switches method does not allow for aftertouch). I've never heard of accelerometers being used.

Then again, I've never made a keyboard. I've cleaned lots of them, though.


Torben

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Curiosity was framed. Ignorance killed the cat.

 

If I wanted to measure the length of time a key was pressed, I would use a microprocessor, which can be programmed to measure times. However, this does not fully address the velocity question. The microprocessor approach can measure length of depression at microsecond precision - can you somehow relate velocity to 'depression time'?

On another line of thought, I built a velocity measurer, based on 2 laser beams. When they were broken and remade, velocity was measured using pretty simple microprocessor code. This does not seem practical in your application, but perhaps a variation of it would work. I am thinking of a user-built keyboard, with 3 layers of foil, and button cutouts. When pressed, the first contact would be between layers 1 and 2 of the foil, and then layer 3. The speed beteen layers 1, 2 and 3 would give you a key press velocity. The theory is sound but I wouldn't care to have to make it.

=OR= How about a keypad with break before make contacts? The break time would be measured, also giving velocity.

 

Not that I know of, but if you read the posts in this thread, you will find some other ways to detect velocity. You can use a microcontroller or not--depends on how you want to solve the problem.


Torben

__________________
Curiosity was framed. Ignorance killed the cat.

 

You seem to be ignoring how velocity sensitive keyboards work?, there are two sets of contacts, one closes before the other - the velocity is very simply worked out by how long the time between the two closures is.

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Re: above comment

The switch would need to be a changeover switch - and you measure th time between the NC contacts opening and th NO ones closing