Controller help needed

[Hlias]

Hello everyone.

I have an array of 20x20 electrodes (a pcb with a matrix of 20x20
terminals) and I would like to be able to control each one of them
separately through a computer.

How would I do that?

Thank you in advance.

 

[Tim Wescott]

On Tue, 01 Apr 2008 07:50:35 -0700, Hlias wrote:

Hello everyone.

I have an array of 20x20 electrodes (a pcb with a matrix of 20x20
terminals) and I would like to be able to control each one of them
separately through a computer.

How would I do that?

Thank you in advance.

Do you mean control their voltage or current? Which one? How
precisely? How much voltage, how much current? How fast do they need to
change?

If you are, indeed, controlling their voltage or current, then you need
appropriate amplifiers driving each electrode, and either each amplifier
needs to be driven by a DAC or you need fewer DACs and a sample-and-hold
circuit preceding each amplifier.

Whatever it is, it'll be a challenge.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

 

[Bob Monsen]

"Hlias" <Hlias.giannopoulos@gmail.com> wrote in message
news:55d27833-4bfa-41ee-ad5d-2bf051f2f5d8@c19g2000prf.googlegroups.com...

Hello everyone.

I have an array of 20x20 electrodes (a pcb with a matrix of 20x20
terminals) and I would like to be able to control each one of them
separately through a computer.

How would I do that?

Thank you in advance.

How much current do the electrodes require?

How is it all wired up? Do you have 20 rows and 20 columns so that one row
and one column intersects at an electrode?

How quickly do you want to change which electrodes are activated?

The answers to those (and possibly other) questions will influence how to do
this.

However, there are nice controller cards that you can control with software
to do this sort of thing. For 40 lines, it'll be fairly expensive (maybe a
couple of hundred dollars)

Regards,
Bob Monsen

 

[Freelance Embedded System]

Hlias wrote:

I have an array of 20x20 electrodes (a pcb with a matrix of 20x20
terminals) and I would like to be able to control each one of them
separately through a computer. How would I do that?
Thank you in advance.

What voltage levels and what currents?
0-3 volts and 20mA each?
If they are all on, that's still 8amps and 24 watts.

What's the application?