Then the circuits are changed so that the electricity comes to each magnet through a wire screen. The rods are re-hung on the electromagnets. As mentioned in the intro, this chronograph also has a Rate of Fire (RoF) mode. This allows the user to determine how many shots per second their paintball marker is capable of. It is pretty straightforward, when switch #2 (S2) is pressed, the chronograph switches from velocity mode to RoF mode and vice versa. All in all, I am quite pleased with how the chronograph works. It wasn't very difficult to build and the code itself is pretty easy to follow. Eventually I plan to update the code and use INT0 and INT1 to detect when a projectile is being shot through the chronograph. This will increase the accuracy and allow for much more efficient code. I would like to make a smaller version of this chronograph, but it is pretty tough to make a lot smaller due to the 16x2 LCD Display. Perhaps I will look into using 7-Segment Displays as a means of relaying the data to the user. If for some reason parcels are required to be redirected then an additional charge might be levied (where applicable). Also if goods are refused or not called for a charge might also be incurred. This list is not a full and exhaustive list and other reasons may apply. Now that we have the chronograph up and working, we will find the worst case scenarios and error tolerances of this device. I will calculate the accuracy according to a 300fps velocity (I assume that the IR Transmitters/Detectors are placed exactly 4" apart, I won't account for manufacturing error).

The difference is that since the short rod started a little later than the long one, the mark is made higher up on the long rod. Since we know that the acceleration of gravity is 32 feet per second per second, we can calculate the time the bullet took to travel between the screens. Used with permission from Travis Terry. Patented in 1874, the Le Boulenge ballistic chronograph was the most accurate way to find the speed of bullets until electronics changed everything, but that was well into the 20th century. Here, John explains how this device works. After all the holes are drilled, the two IR transmitters are placed in their respective holes. Seeing as we used a 3/16" drill bit, the holes diameter is only ~4.8mm. This means that the 5mm LED will not completely fit in the hole, this is what we want though. We just want the IR LED's to slightly poke into the barrel, for two reasons. First, it helps direct the IR beam in a straighter path to the IR detector. Second, it reduces the chance of a projectile striking the IR LED itself and damaging it. The sunshades are extra wide for better reliability on sunny days and are constructed of a durable synthetic material. Caldwell Ballistic Precision Chronograph Premium Kit Contains everything you need to capture reliable velocity data in one convenient kit. Includes Chronograph, IR LED Light Kit, Tripod and Custom Carry Case that conveniently holds all items. The Caldwell Ballistic Precision Chronograph Premium Kit provides accurate velocity measurements across a wide range of shooting conditions. Higher accuracy was achieved by using a high speed 48 MHz processor and by designing a circuit with an advanced data interface that allows each unit to be computer calibrated at the factory after assembly. The end result is the ability to provide much better accuracy than other chronographs on the market (+/- .25%). Although technologically advanced, the unit is designed to be simple to operate, displaying velocity in Feet per second or Meters per second on the large built in LCD screen.When an object breaks the first beam the microcontroller starts a timer (Timer1). This timer will keep running until the object breaks the second beam or the timer causes an interrupt (on the 65,536th instruction cycle). If the object breaks the second beam before the timer causes an interrupt, it will stop the timer and read the 16-Bit value in the registers TMR1H and TMR1L. We can then calculate the amount of time that it took the projectile to travel the length in between the IR beams, which are 4 inches apart, and find the speed of the projectile. The True Ballistic Radar Chronograph measures actual speeds at four different velocities readings from 0 - 300yrds to determine actual ballistic coefficient using G1/G7 drag models. This provides actual data in your conditions, info that provides the difference between a hit and a miss. Whats it worth to you to hit your target? Use the on board display or connect to the FX Radar app to get more out of the ballistic data. Features Say we fired a paintball through the chronograph. Once the paintball has traveled through the chronograph and broke beam #2, we go and read the value of TMR1H:TMR1L (it's a 16-Bit value). For examples sake, we'll say the value we read was 15,930. Here is how we calculate the velocity of the paintball: The Caldwell Precision Ballistic Chronograph provides accurate velocity measurements across a wide range of shooting conditions. Higher accuracy was achieved by using a high speed 48 MHz processor and by designing a circuit with an advanced data interface that allows each unit to be computer calibrated at the factory after assembly. The end result is the ability to provide much better accuracy than other chronographs on the market (+/- .25%). Now that we got all of the requirements and setup out of the way, we can move on and finally get to the exciting stuff. The operation of this chronograph is rather simple, there are two IR transmitters and two IR Detectors, each transmitter/detector pair is placed exactly four inches apart.

After you have drilled the two holes for the IR transmitters, put the drill in the second hole you drilled and make sure it is completely perpendicular to the PVC pipe (there is pictures for most of these steps). Drill through the other side of the PVC pipe. You have just drilled out the hole for the second IR detector. Next, flip the pipe over and measure 4" across the pipe from the exact center of the second IR detectors hole. Make a mark and drill another hole, this one is for the first IR detector.Seeing as I am polling the IR Detectors and waiting to see when an object has broken beam #1, it takes 8 instruction cycles per loop when I am trying to detect if there is an object breaking the beam. Then once it has detected an object, it has one more instruction cycle to perform because it has to start Timer1. After it has done all of this, it has begun recording the time period that it takes the projectile to travel from beam #1 to beam #2. The same goes for beam #2. It takes 8 instruction cycles per "detection" loop and one more instruction to turn Timer1 off. Therefore the worst case scenario is: Now we'll take a look at what calculations are needed to get the actual velocity of the projectile.

Now that is not the actual accuracy of this chronograph. If this microcontroller could detect an object at any instruction cycle, it would have an accuracy of 99.9925% at 300fps because its worst case scenario of not detecting an object when it has broken the beam could only be 83.3333ns before it would actually detect it. If a paintball is traveling at 300fps, it takes 3.3333ms to travel 1ft (1 / 300fps = 3.3333ms). Seeing as our IR Transmitter/Detector pairs are spaced 4" apart, we have to divide 3.3333ms by 3 (1ft / 4in. = 3). So the time it will take the paintball to travel 4" at 300fps is 1.1111ms. We know that the distance between the IR "beams" is exactly 4 inches. So all we need now is to know how long it took the projectile to travel from beam #1 to beam #2. This is what Timer1 is used for. Every instruction cycle (83.3333 ns) the value of TMR1H:TMR1L will increment. So assuming that there are no other sources of error (distance is exactly 4", beams are broken identically on each side, etc) we would have an accuracy of 99.865% at 300fps for this chronograph. This is very good, however, there are many other small sources of error that I have not accounted for. Therefore it is highly unlikely that the chronograph that I build or you build will be 99.865% accurate. Nonetheless, it works quite well and I am very pleased with it. The reason I don't drill through both IR transmitter holes and instead I measure 4" from the second IR detector hole is for accuracy. It is to ensure that both IR transmitters and both IR detectors are spaced exactly 4" apart from each other. This minimizes the error in the calculations and allows for greater accuracy.The PIC18F13K50 is setup to run at 48MHz. It takes 4 cycles to perform one instruction cycle, so the MCU is running at 12 MIPS (Million Instructions per Second). So the time it takes for the PIC to perform one instruction cycle is equal to (1 / 12MIPS), which is 83.3333 nanoseconds/instruction. The bullet then passes through the second screen, releasing the short rod, which again triggers the chisel to make a second mark on the long rod. Please note that your goods may be sent to you in instalments as availability of products can vary. For example certain products have specific delivery requirements which are explained below.

Custom Carry Case Designed to store and transport Chronograph, Sunshades, Light Kit and Tripod Constructed of Durable Ballistic Fabric Heavy Duty dual zipper design These items normally require Identification (Passport) or a Firearms / Shotgun Certificate before they are handed over. Shotguns, Rifles, Airguns and Moderators are usually good examples. When purchasing a 'collection only' item you are in effect paying a deposit for your goods. In all instances you can choose to collect your item from one of our stores (Exeter, Dorset or Newport) or from a 3rd party gun dealer. The latter may be at an additional cost to yourself.

Ballistic Precision Chronograph