More piezo transducer/sensor trigger troubles.

Discussion in 'The Projects Forum' started by jdevereaux, Mar 25, 2013.

  1. jdevereaux

    Thread Starter New Member

    Mar 25, 2013
    I looked around, ran a number of searches here and on google, and while I've picked up several circuits and tested a few of them that claim to work well for this application, I haven't found the right ticket yet, so to speak. I'm hoping some of the brilliant and talented minds on here can help me out. (Please keep in mind that while I'm handy with a soldering iron, to me electronics are largely discreet components that work by way of magical fairy dust...I'm really more of a software guy.)

    My current project requires 2 sensors mounted to a 36" long metal bar (currently using piezo elements as they're cheap and seem to be effective). These senors will feed an xbee module directly, it will have other duties, but this is the one giving me trouble currently. (trying to avoid tying up a microcontroller for such a mundane operation). The idea is that when the metal bar is struck (think drum controller, or a bb shot at it) the sensors detect the hit. However, I'd like to convert that nasty ringing ac wave into a clean digital high/low pulse to detect the hit. Velocity/force and decay time are all unimportant as this isn't intended as a musical device.

    Secondly, It is important that "sensitivity" of the sensors is highly tuneable (thinking a big pot here) so that a hit on one end of the bar triggers trips the first sensor/trigger and a hit on the other end will trigger the other sensor, without triggering the first, and vice versa. Unfortunately the easy answer of using two mechanically isolated bars isn't an option.

    Thirdly, While a clean digital out isn't absolutely necessary as I could pass the analog read value back through the xbee back to base unit and do some basic software comparison signal >threshold=hit, and comparison signal 1>signal 2 & signal 1>threshold=hit on 1, etc...I'd rather solve it in hardware if possible.

    Any thoughts or help would be greatly appreciated as I'm currently driving myself mad with these darn piezo discs.
    Last edited: Mar 25, 2013