Hi, I'm looking to build an arcade style "DDR" dancemat for playing Stepmania on the pc. Instead of using mechanical contact for the sensor construction though I'm looking to use QTC Pills sandwiched between metal plates, for a sensor that's essentially got no moving parts.
I'll say at this point that I've only got a very limited knowledge of electronics, mostly picked up from when I worked at one of the maplin stores for a year. I have an understanding of logic and some soldering skills. I hope that they'll be enough to make this project work.
The basic construction of sensor would be 2 299x299mm metal plates with 12 QTC pills spaced out evenly between them. I'd also want to use the free space around the pills to apply 1mm thick high density, double sided self adhesive foam to keep the sensor held together and to stop the pills from moving around. The bottom plate would be screwed down to the mdf base, while the top plate would be screwed into the underside of an mdf tile, with an acrylic/polycarbonate tile screwed into the top of that.
The wiring from the 4 sensors will terminate at a 9 way D-Sub socket and then I'll use a standard RS232 cable to connect into an ABS plastic project box where the electronics will be housed. I'll be using the guts from an old USB gamepad as the interface (soldering straight onto that is a nice easy solution for me). Will also be soldering to some surface mount buttons to navigate the in-game menus.
I want to be able to do a rough calibration of how much pressure is applied to the tile before it triggers the gamepad's ic to tell the pc that a the tile has been pressed. I think that what I need here would be a voltage comparator connected to the sensor and a screwthread style variable resistor (10MΩ Log?). This is of course where my limited knowledge of electronics runs out.
So, questions at this point are:
Is a voltage comparator the thing that I need? If so, any sugestions on a part number that's easy to get hold of?
Can anyone that's used QTC pills before see any issues with the way that I'm intending to use them?
Anything that I've overlooked?
Many thanks in advance.
-Jon