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  #1  
Old 12-02-2012, 10:39 PM
kylix.rd kylix.rd is offline
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Default Homemade Chronograph

Hello folks... I'm back with another home build project. Within the next week I'll be testing my new homemade 3-stage IR ballistic chronograph. I don't have all the pictures together yet, so I'm trying to gauge the interest in posting more information about it. I can even go into a detailed description of the whole build similar to my other projects. I have to say that this project is not for the faint of heart. I found it extremely challenging, but in was fun and allowed me to bring a lot of my mechanical, electrical, electronic and computing experience into it. Based on some simple calculations, the chronograph should be able to handle well above 4000fps.

Here are a couple of teaser pics.

The screens:




The controller box:

An earlier photo during development showing some test code running for the touch keyboard driver:


And the final UI main screen, shot capture screen and shot series stats and review:




My cave is a little cluttered... Hey! You can see the just lubed cast boolits drying behind the chronograph screens. And there is also a bunch of cardboard I use as a back stop for testing with a .177 pellet/BB air rifle (Shhh!!! don't tell the wife that I took some of her fabric bolt forms). In fact the stats in the last photo are from testing with the air rifle. Yes, the screens are sensitive enough to regularly detect the passing of a BB. I think a 230gr .45 LRN will be easily "seen" ;-).

The controller code will handle up to 32 shots in a series and can be stored in eeprom. I can also save the shot data to the on-board 4gb SD card or send the data out the serial port to the computer directly. It will calculate the min/max, extreme spread, average and standard deviation for each series. Given the graphic display I could even add some code to show charts and graphs ;-).

Here's a quick rundown of the spec's:

For the screens:

o 4 950nm IR emitter LEDs & 4 950nm PIN photodiode for each screen.
o Detection amplifiers right at each screen to minimize noise and interference.
o Lightweight aluminum "U" channels and angle brackets for screen support.
o 3/16" steel rods hold the plastic "U" channel with the detectors 1' above emitters.
o Steel rods just slip into threaded and drilled steel spacers as a quick-disconnect. Detector channels and rods all come apart for transport.

Controller box:

o Main microcontroller - OSEPP Arduino Mega2560 - Frys
o Mass storage - Seeed Studios SD Card Shield - modified to work with Mega2560 - 4gb SD card - Radio Shack
o T6963 based 240x64 graphic LCD with parallel interface & LED backlight
o Fujitsu 6.4" N010-0554-T048A-TW resistive touch panel - Half of panel over display and half over keyboard template
o Surplus aluminum box found at HSC.
o Custom written software along with custom code for touch panel keyboard and on-screen buttons.

For folks in the SF Bay area, the display and touch panel are from Halted Specialties Co. You can find them on their website. The touch panel is only $8 on sale (I paid $12.50).

I shamelessly copied the detector amplifier circuitry from this project: http://nutsvolts.texterity.com/nutsv...?folio=36#pg36... however that is where the similarties ended.

I'll be happy to go into more detail if folks are interested. I think folks main question will be how does it work at the range with "real" bullet velocities? Like I mentioned from the outset, depending on the weather, I plan on trying it within the week. I already know it works perfectly fine in my cave detecting BBs and .177 pellets. This is even with the room being filled with florescent fixtures and several LCD computer monitors. I placed the detectors in the upper plastic "U" channel facing down so that ambient interference is eliminated. I also added some extra "baffling" to keep reflected light at a minimum. I'm getting about a 70-80% detection rate for BBs. I don't have any clue how well the commercial units detect the smaller projectiles since I've never actually used one before. If I had one why would I build one, right? ;-).

I'd be interested in hearing from folks about how well their commercial chronograph works and how reliable the detection is.

If you've already made it this far... I'd say I've piqued your interest ;-).
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  #2  
Old 12-02-2012, 11:04 PM
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interest is piqued

looks like a fun project
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Old 12-02-2012, 11:38 PM
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Old 12-02-2012, 11:41 PM
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I prefer the MagnetoSpeed design, but can appreciate the level of effort that goes into making a chrono. Good luck with your project!
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Old 12-02-2012, 11:44 PM
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Interested
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  #6  
Old 12-03-2012, 12:00 AM
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Quote:
Originally Posted by wizdumb View Post
I prefer the MagnetoSpeed design, but can appreciate the level of effort that goes into making a chrono. Good luck with your project!
How would that work for a handgun with an active slide?
Rifles, sure; handguns I don't see it working.
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Old 12-03-2012, 10:57 AM
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How much has this project cost you so far?
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Old 12-03-2012, 11:33 AM
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im interested.. I too would like to know what it has cost and how well it works with real bullets instead of bb's and pellets.
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Old 12-03-2012, 12:24 PM
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Halted--I just loved that place when I lived in SJ. Legend has it that Jobs and Wozniak got their original Apple stuff there.

Tim
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Old 12-03-2012, 12:34 PM
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  #11  
Old 12-03-2012, 7:09 PM
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Quote:
Originally Posted by gemini1 View Post
How much has this project cost you so far?
So far I'm probably into it for about $150. I justify some of that because the microcontroller can be removed and used for other projects. That was the single largest purchase. About $50 from Frys. I was able to get a lot of the components from Halted. I did buy some IR emitter LEDs for only $.20 each from mouser.com that better matched the sensitivity of the PIN photodiodes that I got from Halted.

If you visit Halted, make a list and plan on several hours roaming the isles. Also, make sure you bring some extra "oooh! that is cool! I gotta get that" impulse buy funds. So budget about 50% more than you plan on ;-).

Some of the components I was able to scrounge from previous projects and what I had in the proverbial "parts bin."

If it works as well as I suspect it will, it will be better than many of the commercially available 3-stage systems. I doubt you could build one for less than a low- to mid-level Chrony, but once you trick out the Chrony with remote displays, PC interfaces and printers, I'm still doing better than that.

If I were to design something to be sold commercially, parts cost, manufacturability, and ease of assembly would all be factors that would have to be taken into account. I have the luxury of using lots of one-off surplus components without worrying about availability. If I do any kind of "here's how you build one" series there will be a lot of steps that will be "exercise left for the reader." That is largely why I said that it isn't a project for the faint of heart.
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Old 12-03-2012, 7:35 PM
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Originally Posted by TimRB View Post
Halted--I just loved that place when I lived in SJ. Legend has it that Jobs and Wozniak got their original Apple stuff there.

Tim
I frequented a place in St. Louis, MO back in the early 80s that was much like Halted. St. Louis had a lot of defense contractors and other tech companies so the local surplus electronic market was well stocked. When I was right out of high-school, I got a job at the place and not much of my paycheck made it home :-/. I was hired on the spot by one of the owners when I was able to recite (from memory ;-) the datasheet specs on a chip that a customer was interested in buying. I just happened to overhear their conversation and interjected myself...
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Old 12-03-2012, 9:45 PM
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So i should be able to pick one up at Wally world soon

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Old 12-03-2012, 10:06 PM
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Originally Posted by BACKTOSHOOTING View Post
So i should be able to pick one up at Wally world soon
Define "soon"...
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Old 12-03-2012, 11:52 PM
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Quote:
Originally Posted by kylix.rd View Post
How would that work for a handgun with an active slide?
Rifles, sure; handguns I don't see it working.
I'm certain they know that this is something folks want. I'd expect to see a version in the coming year that connects to a picatinny rail on many handguns (and some rifles).
It's a bit trickier to attach it to others, sure, but it's not impossible.

WAY faster/easier to setup at the range.
No distance-from-muzzle correction calculations are required
Not sensitive to light.
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Old 12-04-2012, 1:23 AM
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Like wizdumb said, I too prefer the Magnetospeed chronograph, based on experience with two Oehler chronographs an M-33 and 35P. The main flaw in screen based chronographs is the time and hassle of setting up the screens unless one has range facilities where the mounts can be permanently installed. With the advent of inexpensive chronographs such as the Chrony, there is little to recommend building an IR chronograph, except as a rewarding learning experience. The IR chronograph would have greater utility in shooting tunnel or other indoor applications and ballistic labs. I build rifles from manufactured parts, cobbling them together from commercial actions, custom aftermarket barrels, and semi finished stocks not for any other reason than I find it fun to do with a superior product as a result. Same with desktop computers. For all that, most of this stuff in the forums and magazines is the same old stuff rehashed, your chronograph would be something new and different. Sort of like resurrecting the old Heathkits, where us old fans of DIY learned basic electronic skills.

I'm waiting for someone to develop a rifle scope or spotting scope (recoil disturbance of a rifle mounted scope may preclude that option) that incorporates some sort of LASER, IR or RADAR chronograph into the design. The concept would feature constant velocity measurement of the bullet from muzzle to impact, with the ability to recall velocity data at any given distance interval. This could also generate a dynamic B.C. for each bullet weight, shape and constriction, over the range.
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Old 12-04-2012, 1:42 AM
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Quote:
Originally Posted by wizdumb View Post
I'm certain they know that this is something folks want. I'd expect to see a version in the coming year that connects to a picatinny rail on many handguns (and some rifles).
It's a bit trickier to attach it to others, sure, but it's not impossible.

WAY faster/easier to setup at the range.
No distance-from-muzzle correction calculations are required
Not sensitive to light.
The Magnetospeed Bayo can be attached to a modified rifle or pistol rest so the muzzle is properly spaced above the sensor. They show such a test rig on their web site. I would be reluctant to attach the Bayo to heavy recoiling revolvers, such as the .480 Ruger and up, because I have had scope turrets and front sights part company with these revolvers, broken transfer bars, screws that disappeared, and even a hammer spur fall off from metal fatigue. Not to mention the excitement of having the entire revolver fly out of one's grasp, causing a juggling performance suitable for the Three Stooges. Indeed, anyone that has spent long hours in load development for big bore rifles and hand cannons, has suffered concussions, excessive sound level exposure symptoms (dizziness and nausea), scope cuts, bruises, bleeding hands and fingers, elbow damage and eventual carpel tunnel syndrome and arthritis, if not outright bone fractures. I don't want to expose my chronograph to such pounding.

Last edited by Wrangler John; 12-04-2012 at 1:45 AM..
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Old 12-04-2012, 10:39 AM
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Quote:
Originally Posted by Wrangler John View Post
Like wizdumb said, I too prefer the Magnetospeed chronograph, based on experience with two Oehler chronographs an M-33 and 35P. The main flaw in screen based chronographs is the time and hassle of setting up the screens unless one has range facilities where the mounts can be permanently installed. With the advent of inexpensive chronographs such as the Chrony, there is little to recommend building an IR chronograph, except as a rewarding learning experience. The IR chronograph would have greater utility in shooting tunnel or other indoor applications and ballistic labs.
I chose IR so that I would not be beholden to the weather or ambient conditions. I do understand the limits to an optical system. Even an IR system can be screwed up by ambient lighting. I've already seen that first hand where if I'm wearing lighter colored clothes and I stand next to the screens, the reflected IR energy from the florescent fixtures will send the detectors spasming :-).

Quote:
Originally Posted by Wrangler John View Post
I build rifles from manufactured parts, cobbling them together from commercial actions, custom aftermarket barrels, and semi finished stocks not for any other reason than I find it fun to do with a superior product as a result. Same with desktop computers. For all that, most of this stuff in the forums and magazines is the same old stuff rehashed, your chronograph would be something new and different. Sort of like resurrecting the old Heathkits, where us old fans of DIY learned basic electronic skills.
When I looked at the chronograph systems out there the inexpensive ones where very simple and didn't provide any built-in statistcal functions. The others that did have these functions were very expensive or you had to add lots of extra goo in the form of expsensive add-ons. I can twist and turn the data any which way I want by merely updating the code on the device. Something "wizdumb" brought up that I may look at adding is compensating for the distance from the muzzle. Since I can actually measure the deceleration rate of the projectile, I can extrapolate from that all the way back to the muzzle by telling the device how far away it is. I can then get a much more accurate reading of the actual velocity at the muzzle. With my simple air-rifle tests, I easily can see nearly a 5-10 fps drop between screens 1-2 vs. 2-3. As you would expect, BBs decelerate less quickly than flat-nosed pellets. Since I can see the deceleration rate, the B.C. could be calculated as well (or at least the drag coeficient).

Quote:
Originally Posted by Wrangler John View Post
I'm waiting for someone to develop a rifle scope or spotting scope (recoil disturbance of a rifle mounted scope may preclude that option) that incorporates some sort of LASER, IR or RADAR chronograph into the design. The concept would feature constant velocity measurement of the bullet from muzzle to impact, with the ability to recall velocity data at any given distance interval. This could also generate a dynamic B.C. for each bullet weight, shape and constriction, over the range.
Radar... hmmm... Those are based on doppler shift. I wonder how much reflected RF energy would come from a smaller projectile. If shooting away from the radar system, the frequency would drop. A flat bottom projectile would present the best cross-section, whereas muzzle-loaders with round lead balls would tend to scatter the energy in all directions and may not reflect enough energy back. I don't even know if the lead would tend absorb the RF energy and not reflect it.

Just thinking out loud... :-).
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Old 12-04-2012, 10:54 AM
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You mentioned it already but the first thing that occurred to be was that you can with 3 detectors also very accurately identify the effective BC given the precise local atmospheric conditions.

What was the total cost you poured in? I'm extremely interested as I have the skills to do it and the inclination as well but I'd rather know before investing too much time and $$ if it's going to be excessively expensive without having to do any actual shopping. Any detail you want to post or PM would be very much appreciated.
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Old 12-04-2012, 11:28 AM
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Originally Posted by spamsucker View Post
You mentioned it already but the first thing that occurred to be was that you can with 3 detectors also very accurately identify the effective BC given the precise local atmospheric conditions.
Yes, I could add barometric and temperature sensors .

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Originally Posted by spamsucker View Post
What was the total cost you poured in? I'm extremely interested as I have the skills to do it and the inclination as well but I'd rather know before investing too much time and $$ if it's going to be excessively expensive without having to do any actual shopping. Any detail you want to post or PM would be very much appreciated.
I covered some of the cost details in post #11 above.

Last edited by kylix.rd; 12-04-2012 at 11:31 AM..
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Old 12-04-2012, 7:26 PM
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This is ridiculous. I love it!
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Old 12-05-2012, 12:37 AM
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This is awesome. I'd be interested in seeing a tutorial!
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Old 12-05-2012, 7:04 AM
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Holy S! That's badass.
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Old 12-05-2012, 1:16 PM
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FYI the Chrony Beta Master (about $110) does give rudimentary statistical calculations of Low, High, Average, Extreme Spread and Standard Deviation of readings in each of 6 strings with up to 10 shots in a string. I keep all my shot data in an Excel spreadsheet (also usable with free OpenOffice Calc) so these functions are all easily programmed and all I really need to do is to enter the data. Transferring the data via USB/Bluetooth/Wifi would be convenient.
If you look at the Shooting Chrony website, you can get these manuals and see that it uses complicated button press sequences and a user interface conceived in the 80's.

Once you get it working, you might want to make this a little more "bullet proof" (pun intended). The skyscreen sticks should be capable of being shot without tearing out the mounts. I make mine out of easily replaceable wooden dowels. The front should have a deflector so when (not if) you shoot it, you'll minimize the damage and parts replaced.

You might look at some folks who modify their traps by putting black cloth along the "walls" and "roof" to increase the S/N ratio. Cloth instead of cardboard/paper because a slight wind turns the whole contraption into a sail.

Good luck.
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Old 12-05-2012, 3:07 PM
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Quote:
Originally Posted by rsrocket1 View Post
FYI the Chrony Beta Master (about $110) does give rudimentary statistical calculations of Low, High, Average, Extreme Spread and Standard Deviation of readings in each of 6 strings with up to 10 shots in a string. I keep all my shot data in an Excel spreadsheet (also usable with free OpenOffice Calc) so these functions are all easily programmed and all I really need to do is to enter the data. Transferring the data via USB/Bluetooth/Wifi would be convenient.
That's what I found when I was shopping around. To get those kinds of stats from the device, you start moving up in price. The physical hardware is the same, only the software changes.

Quote:
Originally Posted by rsrocket1 View Post
If you look at the Shooting Chrony website, you can get these manuals and see that it uses complicated button press sequences and a user interface conceived in the 80's.
And if I were building commercially, I'd want to make it for as little as possible too. I don't fault them for keeping costs low. Their "user interface" is tedious to use. I am not constrained by that so I can go "go nuts" I have a fully functional touch screen with a keyboard and on-screen "buttons". It's also resistive so I can use a gloved hand or a small stylus. I've toyed with putting a real-time clock chip into it so that I could timestamp all shots and series so I have a record of the data/time so I could track the data over time. With the keyboard, you could even enter other comments and caliber/load information. Its only software at that point.

Quote:
Originally Posted by rsrocket1 View Post
Once you get it working, you might want to make this a little more "bullet proof" (pun intended). The skyscreen sticks should be capable of being shot without tearing out the mounts. I make mine out of easily replaceable wooden dowels. The front should have a deflector so when (not if) you shoot it, you'll minimize the damage and parts replaced.
I intentionally did keep the "brains" separate from the core of the unit. That was one thing I did notice about the lower-end systems, espcially the Chrony stuff. It's certainly compact and easily transportable... but one errant round and you'll be leaving it in the trash bin at the range.

Using wood dowels is certainly a good suggestion. The way I currently have the rods attached is via 1" steel spacers that I tapped one end at 8-32 and drilled the other out to 3/16". The rods just slip in and out. They are friction fit and since the plastic top "U" channel flexes a little it keeps them from flopping around. I had a bunch of them in my parts bin... so I used what I had.

Quote:
Originally Posted by rsrocket1 View Post
You might look at some folks who modify their traps by putting black cloth along the "walls" and "roof" to increase the S/N ratio. Cloth instead of cardboard/paper because a slight wind turns the whole contraption into a sail.

Good luck.
Hmmm... that's a good idea too. I could probably use that thin black, porous cloth that stage designers use for the back "scrim". It needs to block/absorb light while also not flop around on stage in any movement of the air.

Hopefully the use of high-output IR emitters will be enough, but if I run into issues that's still an option.
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Old 12-05-2012, 3:22 PM
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I'll PM you for more technical discussions.
Good job in putting this together. I know it would cost less to simply buy one and be an "appliance operator", but this is a hobby and half the fun is in the making and tweaking of what we are doing.
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Old 12-05-2012, 3:57 PM
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Wow! This is really great, and seriously, kudos to you! But, doesn't this belong in the thread "Home Made Time Machines, Phasers, and Other Devices from the 23rd Century You Can Make in Your Basement"?
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Old 12-05-2012, 6:29 PM
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This is pretty sweet, glad to see another ECE hobbyist putting their skills into a hobby they enjoy. That AVR micro doesn't have an embedded RTC? Should have gone with an MSP430
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Old 12-05-2012, 8:10 PM
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Speaking of MSP430s, I have about 12 bare DIP packages sitting in a box by my bed... I should really get around to doing something with them! I wonder if I can rig up a bluetooth module and start getting smartphone crazy? Hm...
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Old 07-20-2014, 11:57 AM
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Hello Kilix.rd
Congratulations on the project, I found very interesting especially for those who do not have access to high-quality chronograph, like me.
I'm building one too, and used the detector amplifier circuit from the project: http://nutsvolts.texterity.com/nutsv...?folio=36#PG36 , but it did not work.
Have you made ​​any changes on the amplifier circuit to work?
Could provide the amplifier circuit you used?
I am very grateful for your help.

Alan Sales
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Old 07-20-2014, 12:53 PM
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You electronix engineers make me sick...


and green with envy.
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Old 07-20-2014, 1:34 PM
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So ... Have you tested your prototype yet?

What are the results?

To tell you the truth ... I probably would NOT use the circuit that is depicted in the URL you posted.

At 12 millivolts peak .... This circuit does not have enough rejection of ambient conditions to be considered very reliable.

You would be much better off capturing the amplified PD output, (high pass filtered of course), straight into your A/D converter on your microprocessor ... (provided you can sample fast enough)... Then, you can double correlate the ambient conditions with the signal created by the flying object.

... or something along those lines.

Me? personally? I probably just get me one of those el-cheapo Shooting Chrony's... this is what I did.

If I were to do a project like this for myself; I would synchronously control the infrared LED's and sync those up using a DSP along with a high speed sampling circuit. Actually, it does not need to be too fast. This is because the main signal is pretty much in the audio domain.

Doing this, and doing it as a very high quality instrument is not so easy to do. Kudos to you for taking this on.
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Old 07-20-2014, 2:26 PM
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Nerds-R-Us...
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Old 07-20-2014, 5:46 PM
nahpungnome nahpungnome is offline
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Pretty sweet! The laziness in me always wins, so I'd just buy one Same reason I bought a brass catcher instead of making one myself

However, I'd be pretty damn proud if I made my own chrono like you did, you'll surely get some people walking up to you asking about it.
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Old 07-20-2014, 5:55 PM
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OP,

You are awesome. Now make a cheap labradar and sell it to us. Thanks.
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Old 07-21-2014, 8:43 AM
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Quote:
Originally Posted by kylix.rd View Post
So far I'm probably into it for about $150.
You can buy one for about $80, Shooting Chrony F-1 Chronograph on Amazon

http://www.amazon.com/Shooting-Chron...graph+shooting
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Old 07-21-2014, 8:50 AM
J-cat J-cat is offline
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But it doesn't have three screens.
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Old 07-21-2014, 10:15 AM
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Impressive!

What about just starting with an Alpha Chrony and just developing better software?
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Old 07-21-2014, 10:54 AM
Mike402 Mike402 is offline
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Color me impressed as well. Just curious if you gave any thought to going the electromagnetic sensor route (i.e. Magnetospeed). I just bought one, and it seems like there is probably $50 worth of actual components, and what you are paying for is the R&D/new product costs. If this was something you could fab on your own, that would be a WIN
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Old 07-21-2014, 5:16 PM
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