AndAway

Hi Is there a possibility to use for ex. 8xPCD8544 with MidiBox FM?? Andrew

No, You don't have to connect the ground here... You won't get voltages from 0V to 5V, but from something above 0 (on the left you have +5V ane when You press on the farest point to right) to something under 5V, that's why You need to change the software... Take normal pot - when You turn max to left You have a short-circuit between the ground and signal. Turn it max to right - a short-circuit between +5V and signal. With touchpad You'll never have such a short-circuit (but You can match a voltage divider to give You 5V output). Still You need more than 5V for such voltage divider...

That is the bigger one :) It's ok to have 4 contacts. Imagine one axis. You connect +vcc on one side (left), and the other side(right) is signal. The same with the other axis. And the matrix is also nice...

Each of these "2 pads" - the first picture (it is one in fact) has two connectors, one for +vcc and the other to the analog input. You would be able to connect it to the analog in if R=10Kohm, but they are max 1,5 Kohm, so You have to use a voltage divider with an impedance buffer (or play somehow with software). So You have 4 pins: two for +vcc and one for x-output and one for y-output. Btw. I don't think You should separate those 2 layers...

Hi List As moogah said: >For the softpots I was thinking of software that ignores the absolute position and only listens the the change in signal, so that If you slide >up it increments the value, sliding down decrements the value, reguardless of where you touch the pot. I think that this solution is used in laptops. And the soft would be easy (for somebody with basic prog. skills :) ). Also some sensitivity value should be taken into consideration... I've made a very simple circuit which changes the output of the pad to values 0-5V but I don't have a place to post it. I have schematics and pcb in the eagle format (my first drawing). If someone is interested i can send it to him.

Hi Look at the flex sensor. I see 5 sensors, each for one finger, that gives me an idea of midi-glove. That would be nice :) Andrew

That should do the trick - but remember, when You don't touch it, it will send a constant value

What have You connected? XYPad or the soft-pot? It flickers because when You don't touch it works as if it wasn't connected (open circuit) - the same situation when leaving an AIN pin not terminated to ground.

Ok, i've figured it out. I'll post a circuit in the next few days. But as far as the software is concerned... i've no idea :) Andrew

It seems that it won't be so easy... In fact You don't get diffrent resistance values for x and y. Peel off the adhesive paper from the pad and You will see why... There are 2 'sheets' of that carbon resistive material placed one over the other, each with 2 connectors on the opposite side. Pressing in some point makes the 2 sheets touch each other. When You connect a multimeter, You will get values from "upper-left" connectors and "lower-right" connectors. Connecting one sheet (ex. upper and lower pin) makes the multimeter show 0,5 KOhm - impedance of one 'sheet'. When connected pins are lower and left, in this corner You get 0,5KOhm. Diagonal is the line of constant impedance equal 1KOhm. In the upper-right corner of the pad You get 1,5Kohm. The other connector behaves simmilar. The idea with voltage divider may work, but additional impedance buffer may be needed. Any ideas??

The spectra pad consists of 2 resistors, each of imp about 1KOhm. You can build a simple voltage divider - the only con is that You need more than 5V as the input (my PSU delivers 5 and 12V)                      Vin--???---------?-----------Vout         R1-pad   ?                   ?R2                   |                   |                  Gnd Vout=Vin[ R2/(R1+R2)] Assuming Vin=12V, R1=1K and Vout=5V You get R2=450Ohm You will need 2 of those circuits for x and y axis. But I'm not sure if this will work (loaded voltage divider - Thevenin's theorem???), waiting to have some spare time to check if it works in practice. Andrew