Projectile Sensor #2
Due to a few request I decided to make some improvements over my original version of this sensor.
The major improvements are a new 3 PCB design, which makes this much more durable than the previous version. The other huge improvement is using the Honeywell SD5600 Optoschmitt Detector which has a fall time of 15 ns. Previously I was using a standard photo transistor which had a response time of 15 us. This new design is 1000x faster! This actually matters on faster bullets since sometimes the old sensor wouldn’t notice a fast small bullet. The SD5600 never misses.
The only downside to this new design is that it’s a little more expensive. Here’s the BOM.
This sensor has two IR sensors spaced exactly two inches apart. The user inputs the distance from the sensor to the desired position of the projectile when the picture is taken. Based on the time it takes the projectile to travel those two inches between the sensors, a velocity for the projectile can be determined. Since bullets and other projectiles basically travel at a constant velocity, it is easy for the microcontroller to calculate the delay in microseconds until the picture is taken.
PCBs
Here’s a link to the Eagle files I used to create the PCBs.
Using the Projectile Sensor with the Camera Axe
There are 3 PCBs and everything is labeled so it’s supper easy to plug them together. You will need the 3.0.04 or newer version of the Camera Axe software. Turn on the Camera Axe and hit menu until you get to the projectile menu. Set the distance you want the bullet to be from the second gate when the picture is taken and then push the right button until you get to the “Trigger on” menu for the projectile sensor and set this to low. Now hit the set button. If the sensor continuously displays the speed of the projectile that means the sensor boards aren’t lined up correctly. Look at it from the side and bend the boards so the emitter is pointed directly at the detectors. Once it’s sitting there waiting for a projectile put your finger through the two sensors and it will report back to you the speed of your finger. Once you get this it’s working.
Mounting the Projectile Sensor
I mounted a projectile sensor to my pellet gun and it is working great. The pellet’s velocity ranges from 985 feet/second to 1060 feet/second. Below are a bunch of pictures of how I did this mounting.
Results
Tomas said,
June 21, 2010 @ 2:28 am
This is really neat! High-speed action shots are amazing, and it must be nice to have the ability to make the special kit required yourself. Thank you for an interesting article.
Anonymous said,
July 8, 2010 @ 4:05 am
What camera/lens setup have you used for these photographs compared to your water droplet ones? I’m building a similar camera controller and am looking into what macro kit I can get on a relatively small budget.
Maurice Ribble said,
July 8, 2010 @ 4:55 am
I use the Canon 100mm Macro with my trusty old Canon 30D. For these sorts of photos AF doesn’t matter so you could buy an old macro lens on ebay that only has manual focus and save some $$$. There are also other cheaper ways to make a macro lens like extension tubes or the old lens reversal trick. Google can help you out here.
Anonymous said,
July 8, 2010 @ 5:30 am
Thanks. Would you recommend extension tubes on my 18-55mm kit lens? Again, as AF doesn’t matter, I think I might just buy s cheap set of tubes without the electical contacts to test this out.
Modular Robots said,
February 8, 2011 @ 12:02 am
Nice picture collection of the Hobby robot Projectile Sensor its very informative i like it its amazing.
Thank you for post..
Greg said,
June 4, 2012 @ 1:36 pm
Looking at the version in the store, it looks like there are two more orange LEDs below the optical sensors? Could you please explain their purpose. Great product BTW.
Maurice Ribble said,
June 4, 2012 @ 2:11 pm
I posted a video about the updated projectile sensor here: http://www.techphotoblog.com/tpb-34/
Richard Thomas said,
February 5, 2013 @ 10:47 pm
Cool project but I think I can cut the cost down some. The essential parts are the emitters and the detectors. I’m wondering if it would be possible to cut down from two of each too. Perhaps one of each and two small mirrors and detect the double pulse.
Richard Thomas said,
February 5, 2013 @ 10:48 pm
I’m guessing the orange LEDs were indicators to show when the beam was interrupted and not really needed
Sebastien P said,
August 11, 2013 @ 8:17 am
Is it Fast enought for &+ 1250 Feet per Second bullet??? Like .22LR?