microphone (or pressure sensor) to BS2sx

Elie

Hi,

I'm trying to hook up some sort of pressure sensor to a stamp that will detect when I tap it with my hand, and that can send a different signal depending on how hard I hit it (I'm trying to make a drum pad).

I thought of using a microphone but I can't get the basic stamp to see anything. Does anybody know how to hook up a microphone to a BS2sx to get any numerical results?

Also, if the mics aren't a good idea, does anybody know what I can use as a pressure sensor that would be cheap and have (almost) no delay, and how I would connect this thing to a stamp?

Thanks for the help,

-Elie

Dave Paton

Most inexpensive electronic drum pads use piezo discs for sensors, among other things. You can buy drum triggers at your local Guitar Center. You might also want to take a look at the ThumbDrum from Paia, at:
http://www.paia.com/midibrn.htm#thumdrum
and also published in an old issue of Radio Electronics, back when it was a solo publication. Paia also has a note on the sensors they use:
http://www.paia.com/drumsens.htm

Doing realtime force sensing is a little tricky, because you'll need to constantly monitor the voltage from the pads, probably with a multichannel ADC (analog to digital converter). I bet with a tight sampling loop you could make it work pretty well. You'll need to SHIFTIN() the apropriate data from the ADC and look for a maximum value, and then process that value into whatever you want it to do.

-dave

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
This is not a sig. This is a duck. Quack.

KenLem

Good links there, Dave! I didn't even know Paia was still around. I remember building one of their kits over 20 years ago.


Ken
www.speechchips.com

Tracy Allen

Piezo PVDF film is good for this purpose. Look at app notes at this URL:

www.msiusa.com/piezo/

Digikey carries some of the pickup films. A good strong tap can be picked up by the Stamp with no additional electronics other than the film itself.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tracy Allen
www.emesystems.com

radray

The BEST sensor to use for a drum trigger is what the manufacture uses and that is a· piezo transducer part #273-073 And· its only $1.99. Once you removed it from its plastic housing its the exact same trigger element that edrum manufacturing companies use. I know because I sell· Electronic drums and have designed and built my own drum pads and triggers. What I dont know is how the piezo element triggers my sound module, IE voltage, current,resistance. I dont know what it sends to it. I do know that hitting a piezo hard will light a LED for a fraction of a sec. http://www.allinonedj.com/trigger/index.htm·I put up a webpage to help you with your trigger, I hope you can help me find out what it is sending to the sound module as a signal. If you can email or post it here.
RadRay

Forrest

FYI that's a Radio Shack part number for the Piezo transducer in the message above.