i have a project im working on, it will consist of 4 8" round targets in the 4 cornors of a hockey goal. when the targets are hit, i need a sensor for each target that will send a digital signal,(basicly send a 5v ref out) back teto my i/o board. the 8" targets are made out of 3/4" high impact plastic. they will be mounted to the goal with a gate closing sping like these.

rget

this should allow the target to take a hit and return to its position. i need a sensor that can mount to the back of the target, so it can not be hit directly by a hockey puck, but some of the kids are shooting 70 + mph. what type os sensor can i use?

 

I think a piezo transducer or strain gauge should work, with proper amplification and signal conditioning.

 

Coincidentally, I have been experimenting with a piezo transducer used as the trigger for a 555 one-shot. I agree with MrChips that a piezo would work. Are you going to wire the sensors to the control point or use RF?

 

i need 4 of them and each one will be wired to a usb controlled i/o relay board.

 

my main concern is false positives. if a shot hit the goal post next to were the target mounts i do not want it to read as a hit. how accurate are the piezo tranducers? can you adjust the sensitivity of them?

 

I imagine the piezo element sandwiched between the back side of the target and a small backer plate, with some thin padding, such that it would take a direct hit to propel the target rearward, thus compressing the foam sufficiently to put pressure on the piezo. Of course, at this point, I'm just speculating.

 

what do you think about these

http://www.ebay.com/itm/Vibration-Sensor-Module-for-Arduino-Fast-Free-Shipping-USA-Seller-/160943332317?pt=LH_DefaultDomain_0&hash=item2578f85bdd

 

I really don't know enough to have a valid opinion. It's apparently designed to be used with a microcontroller; the Arduino is mentioned by name. Do you have μC experience? The price is certainly reasonable.

 

they will be hooked to a usb relay i/o board. for the price i think i have to try it. hopefully they wont be over sensitive.

https://www.sparkfun.com/products/9669

 

I'd just do it simple and direct with a micro switch such as this:

I'd expect the puck to come in hard and fast so moving the plate & switch isn't the issue, supporting the plate so it doesn't push the switch off it's mounting is.