simpChrony-a Handy Ballistic Chronograph

[pratik_mahale]

BD

IR is the most common sensor used in the Ballistic Chronograph
I have also made similar kind of chronograph few years back with IR
http://indiansforguns.com/viewtopic.php?f=21&t=12570
Also manage to build a chrono like F1 Chronograph


@harshvardhan

I used BPV22NF photo diode with SEP8706 IR LED
You can buy it from
http://in.element14.com/vishay-siliconi ... dp/1469362
They are much cheaper than Sharp GP2Y0A21YK0F

LCD with backlight is power hungry so I will suggest try nokia 5110 lcd its consumes less power

[harshvardhan]

there is option for entering pellet weight by pressing buttons
and buttons are present in lcd keypad shield,which makes it compact
led backlight can be disabled,to save power...

[pratik_mahale]

Ok you brought the arduino UNO with LCD keypad shield

[moulindu]

Hi
First of all welcome back to IFG after your long hibernation, I am glad that you are back again & back with a bang. Wish you were a bit early in approach, that would have made my wallet Rs 6500.00 richer as I would have not spent on Chombro chronograph. Well after using your DIY chrony with Combro MK4 chrony i can say that your DIY chrony is at par with the professionally built one. Since it is barrel mounted I think it is lesser prone to misreads/errors. Moreover DIY chrony is sturdily built & lesser prone to shooting the sensors as the sleeve to hold the barrel is longer, but in my Chombro chronograph i always have to be over cautious not to shoot those sensors. I also think the programming that you did in the audrino meter is very clever with possibility to change the sensor reading sensibility/time(Combro chony has this...can calibrate the sensor reading). Overall its pro DIY product & i can help you patent this as there is a wing in my department which deals with patenting

Regards Moulindu

[harshvardhan]

thank you for your love and support, i want to make it available to shooters who are buying chrono from abroad paying high cost
and letter if any problem persists they suffer a lot

[Big Daddy]

BD

IR is the most common sensor used in the Ballistic Chronograph

Thanks! That's a learning

BD

[ganeshn]

BD

IR is the most common sensor used in the Ballistic Chronograph
I have also made similar kind of chronograph few years back with IR
http://indiansforguns.com/viewtopic.php?f=21&t=12570
Also manage to build a chrono like F1 Chronograph


@harshvardhan

I used BPV22NF photo diode with SEP8706 IR LED
You can buy it from
http://in.element14.com/vishay-siliconi ... dp/1469362
They are much cheaper than Sharp GP2Y0A21YK0F

LCD with backlight is power hungry so I will suggest try nokia 5110 lcd its consumes less power

simbly brilliant Pratik, you are truly multi talented.
guess this design is very practical with greater sweep area than F1 and it can be placed downrange rather than restricting it to knowing just the muzzle velocity, can it be modded to display the reading on the ubiquitous smartphone using wifi.

[pratik_mahale]

Thanks Ganesh
Yes it can be upgraded to send reading to Smartphone via Wi-Fi or Bluetooth

[airgun_novice]

Great work Harshvardhan. Pratik why don't you two pull up your resources and make a "smart" device for Indian and global market. Surly you will find customers worldwide - couple that with Make in India initiative.

[harshvardhan]

For last two months i have studied lots of literatures related to Ballistic Chronograph and have done various R&D to test various logics practically,
I think this is the time to explain little ,to elaborate the principals logics and many other things about Ballistic Chronograph
Lets start with the basic principle, with simple wordings to make it understandable to all members, to make the technology more lucid
How Chronograph works
In ballistic chronograph the bullet or pellet travels from one end to other through a predefined distance..the entry end exit of the projectile
Is trapped in sensors, then the entry and exit time is captured and by subtracting one from another the elapsed time in milliseconds(as projectiles are very fast for example 800 fps) .As the distance is small so minimum unit is required to capture the appropriate time elapsed. then the processor divide the predefined distance by elapsed time and calculate the velocity, then the display circuitry is engaged to show its in readable form, often lcd or seven segment leds are used to display circuitry
What about Sensors
Sensors are device that react to specific physical activity and convert the change into electrical signals. The sensors reacting time should be fast enough to capture the projectile motion otherwise it will remain idle while the projectile passes both the end..
So what I discovered by various R&D process that the reaction time of both the sensors should be lesser than the projectiles passing time.Imagine a moving target which is moving at 1000 FPS and you are shooting with a 10 fps rifle..can u hit it..
On the other hand if you are having a 1000 FPS rifle and shooting a target moving at 10 fps,you will be able to hit it easily……This simple logic applies in sensors sensitivity.
In my prototype I have used IR sensors and further Amplified its signals by advance electronic circuit to enhance their effectiveness.
Sensing area and sensitivity responsiveness are others two factors which should be taken into consideration to build a chrony…if sensors are using light beams of 5 mm and pellet of 4.5 mm is passing through it it will be hard for the sensors to react promptly as beams are partially broken…So, after much R&D ,I have incorporated sensitivity adjustment mechanism in my chronograph so that each time and every time its detects the pellet.
What happens if the sensors are Slow?.....
If both the sensors are slow by say X millisecond. Then time taken will be with error of X milliseconds
Say First sensors time=t1+X and Second sensors time =t2+X,
So the elapsed time T=(t2+X)-(t1+X)= t2-t1
So you can notice that the delay is cancelled in the equation, So delay does not play any role if it is equal for each sensors.

The Processing Unit
Processing unit is a chip that interprets the input signals sent by the sensors and interpret the result and send data to display unit.
I have used Atmega 328 for this Purpose…
These Arduino Boards are having Crystal oscillators to keep track of time of various frequency..In my circuit its 16 Mhz,In Pratikjis Circuit its
8 Mhz,
Higher the number higher the resolution..16 Mhz ossilarators can take pulse in every 4Milisecons,Events in between can not be trapped by the device….
So the time elapsed will be always in the multiples of 4 in case of 16 Mhz and 8 in case of 8 Mhz,
So if elapsed time is actually 350 Milliseconds for 6 Inch or 0.5 foot ,Actual velocity=(0.5*1000000/350)=1428.57;
But the chrony will take the time in multiple of 4 =352 Milliseconds so Calculate velocity=(0.5*1000000/352)=1420.45;
So the deviation is ofvious in case of chronographs..More the mhz of oscillator more the accuracy….
Rest of the Things will be explained in further posts…
Thank You

[ganeshn]

For last two months i have studied lots of literatures related to Ballistic Chronograph and have done various R&D to test various logics practically,
I think this is the time to explain little ,to elaborate the principals logics and many other things about Ballistic Chronograph
Lets start with the basic principle, with simple wordings to make it understandable to all members, to make the technology more lucid
How Chronograph works
In ballistic chronograph the bullet or pellet travels from one end to other through a predefined distance..the entry end exit of the projectile
Is trapped in sensors, then the entry and exit time is captured and by subtracting one from another the elapsed time in milliseconds(as projectiles are very fast for example 800 fps) .As the distance is small so minimum unit is required to capture the appropriate time elapsed. then the processor divide the predefined distance by elapsed time and calculate the velocity, then the display circuitry is engaged to show its in readable form, often lcd or seven segment leds are used to display circuitry
What about Sensors
Sensors are device that react to specific physical activity and convert the change into electrical signals. The sensors reacting time should be fast enough to capture the projectile motion otherwise it will remain idle while the projectile passes both the end..
So what I discovered by various R&D process that the reaction time of both the sensors should be lesser than the projectiles passing time.Imagine a moving target which is moving at 1000 FPS and you are shooting with a 10 fps rifle..can u hit it..
On the other hand if you are having a 1000 FPS rifle and shooting a target moving at 10 fps,you will be able to hit it easily……This simple logic applies in sensors sensitivity.
In my prototype I have used IR sensors and further Amplified its signals by advance electronic circuit to enhance their effectiveness.
Sensing area and sensitivity responsiveness are others two factors which should be taken into consideration to build a chrony…if sensors are using light beams of 5 mm and pellet of 4.5 mm is passing through it it will be hard for the sensors to react promptly as beams are partially broken…So, after much R&D ,I have incorporated sensitivity adjustment mechanism in my chronograph so that each time and every time its detects the pellet.
What happens if the sensors are Slow?.....
If both the sensors are slow by say X millisecond. Then time taken will be with error of X milliseconds
Say First sensors time=t1+X and Second sensors time =t2+X,
So the elapsed time T=(t2+X)-(t1+X)= t2-t1
So you can notice that the delay is cancelled in the equation, So delay does not play any role if it is equal for each sensors.

The Processing Unit
Processing unit is a chip that interprets the input signals sent by the sensors and interpret the result and send data to display unit.
I have used Atmega 328 for this Purpose…
These Arduino Boards are having Crystal oscillators to keep track of time of various frequency..In my circuit its 16 Mhz,In Pratikjis Circuit its
8 Mhz,
Higher the number higher the resolution..16 Mhz ossilarators can take pulse in every 4Milisecons,Events in between can not be trapped by the device….
So the time elapsed will be always in the multiples of 4 in case of 16 Mhz and 8 in case of 8 Mhz,
So if elapsed time is actually 350 Milliseconds for 6 Inch or 0.5 foot ,Actual velocity=(0.5*1000000/350)=1428.57;
But the chrony will take the time in multiple of 4 =352 Milliseconds so Calculate velocity=(0.5*1000000/352)=1420.45;
So the deviation is ofvious in case of chronographs..More the mhz of oscillator more the accuracy….
Rest of the Things will be explained in further posts…
Thank You

In fact the heart of the chrony is a very accurate clock and the sensors only act as binary devices, its not how fast the sensor are but how sensitive they are rather to generate the signal/event 0 and 1,the time starts when it registers a "1" from the first sensor and stops with "1" from second sensor.once the time and the distance are given velocity follows.for obvious reasons higher the frequency of the clock finer the granularity of velocity.

[harshvardhan]

Sensor generates signals only high and low,which later interpreted by the processor as boolean value true and false denoted as 1 and 0.the pulse stays for micro second so the output of sensors is further amplified and feeded to the processor.to do the time count between boolean value change.the processor uses the crystal oscillator for time ticks

[pratik_mahale]

Good explanation Harshvardhan

For higher resolution using 16/20 MHz crystal is not a big deal just needs to do small changes in the software that you also know.
You can see in my post I have made the same thing first but one has to be very careful about the PVC pipe & the wiring attached to the barrel when he is cocking the gun so I drop that idea & used 5 “X 5 “screen which gives me more flexibility in testing more than one gun at a time & you can measure the velocity of pellets at different distance by placing the screen at desired distance.

I have design my won circuit & PCB

Chrono.jpg

It has 64 k of EEPROM can store 100 series of 100 shots
Also have manual calibration option can send data to PC via Serial port
Big Display with Back light ( 20 x 4 LCD) for better vision
Power saving mode

[harshvardhan]

Good explanation Harshvardhan

For higher resolution using 16/20 MHz crystal is not a big deal just needs to do small changes in the software that you also know.
You can see in my post I have made the same thing first but one has to be very careful about the PVC pipe & the wiring attached to the barrel when he is cocking the gun so I drop that idea & used 5 “X 5 “screen which gives me more flexibility in testing more than one gun at a time & you can measure the velocity of pellets at different distance by placing the screen at desired distance.

I have design my won circuit & PCB

Chrono.jpg

It has 64 k of EEPROM can store 100 series of 100 shots
Also have manual calibration option can send data to PC via Serial port
Big Display with Back light ( 20 x 4 LCD) for better vision
Power saving mode

Thank you pratikji,
I have also done experiment with Serial window and EPROM and Larger pellet detection area like yours,
but every thing is advantage in larger detection area except accuracy of chrony....Pipe chronys are more accurate due to its constant straight motion path,
Larger areas as well as f1 chronys suffer from angular displacement of projectile,hence increase pellet path,which results in error as chronys are feeded with predefined distance,Later i will explain how to minimize the error and amount of error..
What do you think pratikji....
You are the first Man to build indiginious chrony and I am the Second...I dream to Provide all Ar Shooters a handy chrony..

[pratik_mahale]

Best of luck & let me know if you need any kind of help

To develop any microcontroller based project one has to give time with dedication but for some reason I have lost touch in electronics from few months may be because of knifes