I could use your help !. I'm trying to use a bunch of 1129 touch sensors with Max to build a sort of musical instrument.. I have no trouble creating a simple demo where the 1129's can trigger simple midi notes in Max.. The issues I'm having are with sensitivity, hysteresis and delay
Sensitivity- I've attached the 1129 touch point to a piece of fine copper mesh behind a thin lexan sheet . I'm easily able to sense my hand on the other side of the lexan.. what's bugging me a bit is that the plate is quite sensitive to surroundings.. eg. metal beneath a table, etc. I was trying to figure out a how to calculate the right size for my sensing pad.. and/or.. a way that I could discriminate between static coupling and the presence of the hand. I believe the sensor is ratiometric.. but the phidget interface in max seems to be showing only two values.. 0 or 999, Is there a way to change the scaling on these things so I can some interpretation about how near and/or big something is ?
hysteresis- I'm also noticing that there is some sort of built in hysteresis in the 1129. I.e the Phidgetinterface registers presence of a hand at (say) 2cm distance.. but then does not register that the hand is not present until it's raised to (say) 5 cm. Is this hysteresis somehow in the phidget interface.. or is it set in the 1129. If it's the latter, is it possible to control ? It's creating some difficulty in 'playing' the instrument
delay- similar question.. I've created a simple feedback mechanism using leds to indicate when the 1129 sensor is active. There appears to be a surprisingly long (many mS) long delay between the placing of your hand and the sound of the midi note. I've tried changing the sample rate (setSampleRate) message on the phidgetinterface.. I've tried -1 (trigger on change) and 1 (1 ms poling i think. or is it 100mS ? ) and 0.. (no clue).. -1 seems to have the least delay... Any ideas on how to improve this ?
Is it possible that the whole 1129-> phidget 8/8/8 controller ->Max interface is going to be too slow to use to trigger a musical instrument ? Have others tried to do similar things and either succeeded or failed ?
Any help/comment on any of the above would be most appreciated !
ps. On a similar bent.. does anyone have a contact touch sens design that would work with phidgets ? Perhaps one that works with coupled noise (ie. you need to physically touch the antenna).. that would be a nice compliment to the existing sensors...
pss. . one suggestion.. there should be some sort of of better solder connection for the sensing tab on the 1129..
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