Competition Electronics ProChronoLTD CEI-3825 User manual

Please read this manual!
This manual contains
setup information
necessary to achieve
proper performance
from your chronograph.
OPERATING INSTRUCTIONS
Look inside
for accessories to use
with your ProChrono LTD!

PROCHRONO LTD
USER MANUAL / OPERATING INSTRUCTIONS
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TABLE OF CONTENTS
How It Works / Lighting Considerations .............................. 3
Common Conditions that May Cause Problems ......................4-5
Using the ProChrono LTD with Dierent Projectile Types .............6-7
Battery Installation ................................................. 7
Mounting the Chronograph ......................................... 7
Installing the Guide Wires & Difuser Hoods ........................... 8
Operating the Chronograph......................................... 8
Meters per Second/Feet per Second Selection ........................ 8
Getting Started: Recording Projectile Velocities ...................... 9
Duplicate Velocities ................................................. 9
Low Battery Indication .............................................. 9
Error Indication ..................................................... 9
Working with Projectile Velocities & Statistics ....................... 10
Pushbutton Controls ............................................10-11
Specications ..................................................... 12
Limited Warranty .................................................. 13
Accessories ........................................................ 14
Thank you for purchasing our product! It is important to
read and understand this manual before trying to use your
new chronograph.
We are here to help. If you have any questions or comments, please contact us
at 815-874-8001 or www.competitionelectronics.com. The ProChrono LTD is
designed and built in the USA, and with proper use and care it will give you many
years of trouble free service.

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PROCHRONO LTD
USER MANUAL / OPERATING INSTRUCTIONS
How It Works
The ProChrono LTD operates on the principle of measuring the time it takes for an
object to travel from the rst projectile sensor to the second projectile sensor. The
sensors, mounted internally in the case, monitor light through the two rectangular
openings in the top of the case. These sensors are specially designed electrome-
chanical devices that can detect the small changes in light intensity that occur
when a projectile interrupts light rays shining into the sensor opening.
If you can imagine looking up at the sky through a tube, you will gain an under-
standing of what the sensors see. The only light they see is what is directly above
them. Any change in light caused by an object passing over them is converted to a
signal that is detected by the chronograph circuitry. It then measures the elapsed
time between the light interruptions, converts this time into velocity, and displays
it on its LCD screen.
Lighting Considerations
Lighting Conditions
As mentioned above, the ProChrono LTD is a light sensing device. In the course
of use it must cope with a multitude of dierent lighting conditions… sunny
clear skies, overcast days, low light situations, reections, dierent colors and
shapes of projectiles, etc. Although the ProChrono LTD works awlessly over a
very wide range of conditions, there are times when the environment can aect
chronograph performance.
Diuser Use
It may be counterintuitive, but the best natural conditions for using the ProChrono
LTD are overcast, or cloudy days. This is because the ProChrono LTD works best
with a diused light source.
For this reason, white plastic diuser hoods are provided with the unit for use
on clear, sunny days. This will insure that the light that the chronograph sensors
see from above is homogenous and scattered and will greatly reduce errors in
velocities and missed detection.
On an overcast day, it is generally better to remove the diusers. This is because
the clouds act as diusers, so no further diusion is needed and is advantageous
to allow more light into the chronograph.

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Some Common Conditions that May
Cause Problems
You can encounter a wide variety of lighting conditions if you use your
chronograph outside. The following are some things to look out for:
Reections
On sunny days, reective projectiles may cause “glints” which can induce velocity
errors. This phenomenon is minimized by using the diuser hoods. However,
depending on the position of the sun, further setup adjustments may be
necessary. If false readings occur with the diuser hoods in place, you can correct
the problem with one or more of the following steps:
• Change the position of the chronograph relative to the angle of the sun
• Color the bullet tip with a black, permanent marker
• Move the chronograph to a location in the eld of a shadow cast by a building
or an opaque wall. Make sure the sensors have a clear view of the sky but the
chronograph itself is within the shadow. An alternate method for this is to
use shields taped on the sides of the guide rods to create the shadow. Be sure
to use cardboard or something similar that will not cause any problems with
ricochets. This will eliminate reections from direct sunlight, while still assuring
that the chronograph has a direct view of the sky. In some cases, doing this
may reduce the incoming light level too much and make the chronograph less
sensitive
Trees
You should not locate your chronograph in the shadow of a tree since the
movement of leaves and branches can cause instability in the lighting
environment.
Sunrise and Sunset
The lighting conditions at sunrise and sunset can cause errors due to reections
(glints), skewed shadows, or low light levels because of the extremely low angle of
the sun.

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PROCHRONO LTD
USER MANUAL / OPERATING INSTRUCTIONS
Electrical Interference
It is unlikely but possible that use of the chronograph in close proximity to a radio
tower, microwave tower, or large power facility could cause errors and functional
problems. Avoid use in these areas if you encounter these problems.
Using the Chronograph Indoors
Common problems that occur indoors include the following:
Not Enough Light
Indoor lighting is often not suitable for use with the chronograph. Most
common incandescent lamps positioned directly above the chronograph are
not a good light source because they provide an uneven amount of light over
the sensing area. A white background with even amounts of light over the
sensing area works best, (such as an incandescent ood lamp shining up onto a
white surface above the chronograph)
Wrong Kind of Light
Florescent lamps will not work as a light source for your chronograph, because
although we cannot see it with our naked eye, they are pulsing many times per
second and the chronograph can detect this which renders it useless because
the cycle rate is similar to the speed of projectiles.
If you would like to use your chronograph in an area where improper lighting
conditions exist, Competition Electronics oers a specially designed indoor
lighting system. More information on this is found in the“accessories”section of
this manual.
Lighting & Accuracy
Adverse lighting conditions can cause accuracy issues, and having read the above
you can understand why. Any change in light intensity that a sensor detects other
than the shadow of the intended projectile will result in errors.
(Some Common Conditions that May Cause Problems continued...)

PROCHRONO LTD
USER MANUAL / OPERATING INSTRUCTIONS
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Using the ProChrono LTD with Dierent
Projectile Types
Pistols & Rifles
The main consideration here is probably muzzle blast. Make sure you stand back
far enough from the chronograph to avoid the muzzle blast triggering the sensors
and introducing velocity errors.
• For pistols, the muzzle to chronograph distance should be 5 to 10 feet.
• For ries, we recommend a muzzle to chronograph distance of 10 to 15 feet.
If muzzle blast is aecting your readings, move back to resolve the problem.
If you are using a scope, be sure to check the boreline-to-scope distance and raise
your aimpoint to accommodate this measurement, otherwise the projectile may
hit the chronograph.
Shotguns
To chronograph shotgun loads, do not install the guide wires and diuser hoods
under any type of lighting conditions or they may be hit by the shot mass. Due to
the size and shape of a shot mass, diused light is not necessary.
Start by standing at a distance of 5 feet from the muzzle of the gun to the
chronograph and aim about 6 inches above the unit.
You may have to experiment with shot placement and muzzle distance to nd the
right spot to measure your particular load. If you stand too far away, the shot can
spread out too far causing inaccurate velocity readings, and the wad can separate
from the shot column and may hit and possibly damage the chronograph.
See the CEI Debris Shield in the accessories section of this manual, it can provide
an additional measure of protection.
Bow and Arrow & Crossbow
Make sure that you stand a little more than one arrow’s length away from the
chronograph when shooting to assure that the arrow is not accelerating when it
reaches the chronograph, otherwise your velocity readings may be inconsistent.
Regarding the arrow tips, we recommend using dark colored eld points for best
results.

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PROCHRONO LTD
USER MANUAL / OPERATING INSTRUCTIONS
Paintball Guns
Muzzle to chronograph distance is not a factor with paintball guns, however
paint buildup on the unit may aect its performance. See the CEI Debris Shield
in the accessories section of this manual, it can provide an additional measure of
protection.
Airguns, BB Guns, Pellet Guns & AirSoft Guns
Muzzle to chronograph distance is not a factor with these types of guns. The main
issue is that BB’s are probably one of the most dicult projectiles to measure
using light-based techniques because they are small and shiny. However, with
proper setup and lighting conditions the ProChrono LTD will measure them
reliably.
Miscellaneous
You may think of other uses for the chronograph. For example, some have used it
to measure the speed of sporting clays. If you can get it to pass over the sensors,
you can probably measure the velocity.
Battery Installation
Begin by installing a new 9 volt alkaline battery in the chronograph battery
compartment. There is also space to store a spare. You can expect at least 20 hours
of operation from a new alkaline battery.
Mounting the Chronograph
The chronograph may be placed on a sturdy table or mounted to a tripod
using it’s molded-in 1/4-20 threaded insert. Be careful to prepare adequately
for windy conditions, especially if you are using a tripod. The diusers make the
chronograph susceptible to wind gusts.
(Using the ProChrono LTD with Dierent Projectile Types continued...)

PROCHRONO LTD
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Installing the Guide Wires & Diuser
Hoods
(Note: Diuser Hoods are intended for sunny conditions only)
Insert the 3/16” rods into the holes on each side of the plastic diuser. Insert one
of the rods into the chronograph. Insert the other rod into the opposite side of the
chronograph.
Operating the Chronograph
To turn the chronograph on, move the small black slide switch on the side of the
chronograph to the “ON”position. The display will briey show all segments.
Meters per Second/Feet per Second
Selection
If you want to use the chronograph in ft/sec mode, just turn it on. To register
velocities in meters/sec mode, hold down the “review” button while you turn on
the chronograph until you see the “rdY” message.
You must do this each time you turn on the chrono when meters/sec readout
is desired.
Projectile
Sensors
Delete String
Button
Display Readout
Review Button
String Change
Button
Redisplay
Button
On/Off Switch
Delete Shot
Button
Battery Compartment
Tripod Mount
Insert 1/4-20 Thread
Delete
Shot
Delete
String
Review
Redisplay String
Change

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PROCHRONO LTD
USER MANUAL / OPERATING INSTRUCTIONS
Getting Started: Recording Projectile
Velocities
Getting a velocity is as simple as turning on the chronograph and shooting over it.
You must shoot along the long dimension of the chronograph within the triangle
formed by the rods and the diuser screens (even if they are not installed), being
careful not to hit any parts of the chronograph. On detection of the projectile, the
display will briey show the current shot string and updated number of shots in
the string, followed by the velocity recorded.
Duplicate Velocities
If the chronograph should record 2 shots of
the same velocity one after the other, the“duP”
(duplicate) message will appear (Fig. 1), followed
by a single digit number representing the duplicate
velocity. If subsequent shot velocities are also the
same, the number will increment. If 10 sequential
duplicate shot velocities are recorded, the number
will be reset to 1.
Low Battery Indication
If the battery voltage becomes low (6.8-7.0 volts),
the chronograph will ash the message“bAt” at
intervals to signal that it is time to change the
battery (Fig. 2). If the battery voltage drops below
6.8 volts, the chronograph will ash the message
“CbAt” to let you know it is time to change the
battery, and the unit will no longer register velocities.
Error Indication
In the event a signal is recorded by the rst sensor,
but no signal is recorded by the second sensor, an
error “Err” message will ash momentarily (Fig 3). You
should try adjusting your aim position if this occurs.

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USER MANUAL / OPERATING INSTRUCTIONS
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Working with Projectile Velocities & Statistics
The ProChrono LTD allows you to observe and work with your velocity data. This is
done through the use of the front panel pushbutton controls described below.
String and Shot Navigation
Each time the ProChrono LTD successfully detects a shot, it’s velocity is stored at
the end of the currently selected string.
The ProChrono LTD can store up to 9 strings of 99 velocities each and retain them
in non-volatile memory even if you turn the chronograph o and remove the
battery. You can shoot now and the chronograph will store your velocities for later
review.
Pushbutton Controls
String Change
When the ProChrono LTD is rst turned on, it automatically positions itself at the
end of shot string 1 and displays the most recent shot velocity. By pressing the
“String Change”button, the user can sequentially select each one of the 9 string
memories into which the unit will place the shot velocities as they are detected.
When shot string 9 is selected, pressing the“String Change” button will increment
back to string 1.
Review Shots and Statistics for a String
The “Review” button will cause the ProChrono LTD to display the previously red
shot velocity within the current string. Upon each subsequent press of this button,
the previous shot velocity will be displayed until the user reaches the rst shot in
the string. At this point, pressing the “Review” button again causes the display to
begin showing the statistics. The display will cycle through High Velocity, Low
Velocity, Average Velocity, Extreme Spread, and Standard Deviation. Finally,
pressing it again will reposition the display to show the last recorded shot velocity
in the string.