best way to detect impact on a paper target...

Brownout

Joined Jan 10, 2012
2,390
Back when shooting popup targets was my profession, a 'hit' was considered anywhere on the target, regardless if it was a 'bullseye' or not. That a prefectly valid goal, IMO.
 

Bernard

Joined Aug 7, 2008
5,784
Target 22 X 28 X .oo9 in. paper, spring suspended from 4 corners.
Sensor, seismometer ( 3 in speaker with 3 US penneys glued to voice coil & 8 ohm : 1k ohm transformer ).
Sensor suspended horizontally from bottom center of target, light strikes regestered ( .2 V - pulse ) from all quadrents.
Moveng target back & forth gave no output.
 

Thread Starter

Jesse Klein

Joined Dec 5, 2014
26
I was told that the target is a E-Type Facer. Which looks like a silhouette. So a hit on that would mean a hit in general, a miss would not even hit the target.
These are the targets that might be used:
http://www.letargets.com/content/e-target-e-type-military-plastic-target-green.asp
http://www.letargets.com/content/usmc-srq-us-marine-corps-marksmanship-qualification-target.asp
http://www.letargets.com/content/fac-gr-die-cut-e-type-target-facer.asp

I was also given a ball park budget finally. Now I can start sourcing parts.
Target 22 X 28 X .oo9 in. paper, spring suspended from 4 corners.
Sensor, seismometer ( 3 in speaker with 3 US penneys glued to voice coil & 8 ohm : 1k ohm transformer ).
Sensor suspended horizontally from bottom center of target, light strikes regestered ( .2 V - pulse ) from all quadrents.
Moveng target back & forth gave no output.
Bernard,

Is something you just tested? and it worked? I wont be able to suspend a sensor in the middle of the target. It will have to be mounted at the bottom of the target
 

wayneh

Joined Sep 9, 2010
17,496
20.8 uS implies a frequency domain of 24,000 Hz
I'd approach it a little differently. There is a pressure wave generated when the bullet strikes the small disk of paper and knocks it out of place. The energy in that pressure wave travels through the paper and through the air to the fingers and ears of our imaginary observer. It's a small amount of energy - the bullet is not slowed much - but my gut tells me the observer would certainly hear the impact and would probably feel it in the paper also. A sensitive instrument should be more than able to detect the impact.

I can watch the live data streaming from my laptop's accelerometers. I'm impressed that it easily registers vibrations that I don't notice.

But playing around with applying this to the OP's problem would take time. Bernard's results are intriguing.
 

Bernard

Joined Aug 7, 2008
5,784
Note word " bottom " center of target ie, center of lower edge. Test about an hour old. Crude but satisfied my curosity.
 

Bernard

Joined Aug 7, 2008
5,784
Frame - light weight wood, maybe 2 X 1/2 in held together with C clamps. Shaft has 2 in steel strap welded on to clamp frame to. 6 in crank fixed to shaft. Connecting rod connects crank to wheel so that 180 deg wheel rotation gives 90 deg. target rotation. Sensor hangs on bottom of parer target with aligator clip. Target held to frame with springs or rubber bands & alligator clips.
A gearhead motor turns wheel, single direction. Maybe something like a window lift motor, All Electronics, Cat# DCM- 467, 60 RPM, 12V 2.5 A no load. Torque ??
Another version of sensor uses a 64 ohm 2 " speaker with 2 gm wt glued to voice coil. no transformer required.
 

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Thread Starter

Jesse Klein

Joined Dec 5, 2014
26
Frame - light weight wood, maybe 2 X 1/2 in held together with C clamps. Shaft has 2 in steel strap welded on to clamp frame to. 6 in crank fixed to shaft. Connecting rod connects crank to wheel so that 180 deg wheel rotation gives 90 deg. target rotation. Sensor hangs on bottom of parer target with aligator clip. Target held to frame with springs or rubber bands & alligator clips.
A gearhead motor turns wheel, single direction. Maybe something like a window lift motor, All Electronics, Cat# DCM- 467, 60 RPM, 12V 2.5 A no load. Torque ??
Another version of sensor uses a 64 ohm 2 " speaker with 2 gm wt glued to voice coil. no transformer required.
Awesome thanks.

I think I am going to use this:

http://www.jameco.com/jameco/pressroom/recipe4.html

I am going to buy a bunch of different elements similar to this and try them out.

http://www.jameco.com/webapp/wcs/st...amecoall&ddkey=http:StoreCatalogDrillDownView

How do I modify this circuit to accept 24V DC?
I also do not want it to light up an LED, I want it to trigger a solenoid. This solenoid probablly:

http://www.digikey.com/product-detail/en/F0474A/527-1027-ND/668312

What about fusing it? What size fuse should I use?

 

Bernard

Joined Aug 7, 2008
5,784
There are less expensive solenoids, 24V & 12V, on All Electronics, Electronic Goldmine, & others.
Are you limited to just 24V?
You will need a pulse generator following comparator output with a relay driver ( 555 & FET ).
 

Thread Starter

Jesse Klein

Joined Dec 5, 2014
26
There are less expensive solenoids, 24V & 12V, on All Electronics, Electronic Goldmine, & others.
Are you limited to just 24V?
You will need a pulse generator following comparator output with a relay driver ( 555 & FET ).
My power input will be 120V AC and 24V DC.

If I got a 12V solenoid, I would need to get a voltage regulator, which just adds yet another piece.
I will check out the solenoids on those sites.

Does the pulse generator replace the LED? I am not an electronics person. I am a point to point wiring, mechanical assembly guy. So forgive me if that is basic stuff that I should know. I have barebones basic electronics knowledge. Which is why I am on this forum, to learn.
 

alfacliff

Joined Dec 13, 2013
2,458
no mention of caliber, a small pointed bullet like fired from an ar15 would make very little movement to the paper. the muzle blast might be greater, especially on a large area target.
 

Thread Starter

Jesse Klein

Joined Dec 5, 2014
26
no mention of caliber, a small pointed bullet like fired from an ar15 would make very little movement to the paper. the muzle blast might be greater, especially on a large area target.
primarily .223 or 5.56 rounds, but I want to detect a wide range of munitions.
 

alfacliff

Joined Dec 13, 2013
2,458
I do a lot of club shooting indoor and outdoor, and the targets do not move very much when pierced by a .223. my .44 mag, on the otherhand makes them move quite a bit. I have even seen near misses cause the paper targets to wave.
 

Thread Starter

Jesse Klein

Joined Dec 5, 2014
26
They might not move much, but if something pierces the paper or plastic target, it has to create some vibration. I am trying to figure out how to detect that vibration and make it trigger a solenoid.
 

blocco a spirale

Joined Jun 18, 2008
1,546
My power input will be 120V AC and 24V DC.

If I got a 12V solenoid, I would need to get a voltage regulator, which just adds yet another piece.
I will check out the solenoids on those sites.
If the drive pulse is short enough there is no reason why you could not use a 12V solenoid on a 24V supply. If necessary; just add a series resistor to limit the current.
 
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djsfantasi

Joined Apr 11, 2010
9,156
Can you have a heavy metal backing, angled down to control ricochets? A sandbag beneath the back guard would trap the bullets. That way a round would certainly create a loud enough sound and/or vibration to detect.
 

Bernard

Joined Aug 7, 2008
5,784
Lost my post again. Either 12V or 24 V solenoid will work. Just need a resistor & 12 V zener diode or 7812 VR for low V part of ckt. Keep LED, good for testing. I believe that the Jameco # 1956784, $ 3.25 or # 336314 $ 1.59 speaker would make a good seismometer. I like the 5 cm but the 2 cm has advantaje of having a case which with care back can be removed to add a weight.
What part of the world are you in? I have a pot full of the 2 cm sensors available.
 
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