I'd appreciate on any advice or explanation for what happened with the chono yesterday. It worked great for 70 rounds, then error'd for 10, then nothing for 30, then no problems with the next 50 or so. I can't think of what I did to make it start working again except to change the powder/bullet. 

https://2ahawaii.com/index.php?topic=26240.msg254739#msg254739

https://www.amazon.com/Caldwell-Ballistic-Precision-Chronograph-Premium/dp/B00HTN5290/ref=sr_1_1

I'd appreciate on any advice or explanation for what happened with the chono yesterday. It worked great for 70 rounds, then error'd for 10, then nothing for 30, then no problems with the next 50 or so. I can't think of what I did to make it start working again except to change the powder/bullet. 

https://2ahawaii.com/index.php?topic=26240.msg254739#msg254739

https://www.amazon.com/Caldwell-Ballistic-Precision-Chronograph-Premium/dp/B00HTN5290/ref=sr_1_1

Operator error.

I usually charge $50 for that, so ... you're welcome!   

Are your shoes on too tight?

Are your shoes on too tight?

Shoes?  This is Hawaii.  Nobody wears shoes in the house!   

So seriously, was it operator error? It's not like I can run out there and mess with the chrono while the range is hot. After the 7th set with the errors, I turned the chrono off/on during the break and got no errors but also no measurements. I did nothing to get it to start measuring the ARcomp rounds. Very puzzling.

For me, Light activated chronograph units have always been finicky.
Back in the 80's There was only the Oehler 35p. Very expensive.

So I bought a Tepeco time meter for much less.
It was primitive but accurate. I had to wait for the right daylight to make it work.
The best light is cloudy days. Conversely, the worst days are clear sunny days. Especially around noon.
I found that sometimes I could cheat the sun by tilting the sensors maybe 45 degrees left or right to reduce the amount of light.
Eventually I ended up with a Chrony, but even with the sun baffles, it's still finicky.
That's why people buy the magnetospeed or radar units.

I pulled the Tepeco out and it still works....

Hey RKL 

 We've had the same unit for about a year now and here's what we've found.

1) Sunlight is an issue. At our range, the chrono used to go chronic at the same time of the day. Found it was the angle of the sun hitting the chrono.
a) adjust the sun shades or better yet, b) use the light kit. for some reason it nullifies the sun light issue.

2) Having it  closer than the recommended 15' v it receives "muzzle blast" which causes intermittant error message.
Someone next to you with a compensator or just plain loud or powerful firearm will also cause your unit to error.

Opto chronys uses 2 optical sensors to detect the bullet and computes the difference in time when the bullet passes through to give you velocity. Lighting conditions obviously have a factor. I use a white transluscent plastic for screens to give sensors a solid background. Like shooting, consistent conditions. You can use LEDs to give the optical sensors a more consistent and predictable light source.

Like every one said, light.  Different lighting conditions mess it up.

I was about to build a screened in box, to put my optical chrono in, to try and even out the light the sensors see..   then I decided to get a magneto speed instead.    Too much headache and hassle trying to set up even more extra shat

Just for $#it's and Gigg!es, try just putting a dark towel over the top of light lenses letting it drape all down the sides.
Too easy ?

Hey RKL 
 We've had the same unit for about a year now and here's what we've found.
1) Sunlight is an issue. At our range, the chrono used to go chronic at the same time of the day. Found it was the angle of the sun hitting the chrono.
a) adjust the sun shades or better yet, b) use the light kit. for some reason it nullifies the sun light issue.
2) Having it  closer than the recommended 15' v it receives "muzzle blast" which causes intermittant error message.
Someone next to you with a compensator or just plain loud or powerful firearm will also cause your unit to error.

Hey Rocky,
I'm thinking that the muzzle blast is the most likely explanation. I don't have a muzzle break on the 223. In the bright sunlight, I have to set up the unit in the shade about 4 to 6 feet in front. The LED lights are installed. At the 7th load set, the muzzle blast overpowered the units ability to detect the bullet. I recently installed a muzzle break on the AK so wasn't a problem. There's not too many cloudy days at Kokohead. Perhaps it's time for Dexter to add a muzzle break to the varmint rifle.

Just for $#it's and Gigg!es, try just putting a dark towel over the top of light lenses letting it drape all down the sides.
Too easy ?

Worth a try. If the towel was long enough, I could clip it together under the unit so it doesn't sail away in the wind.

Opto chronys uses 2 optical sensors to detect the bullet and computes the difference in time when the bullet passes through to give you velocity. Lighting conditions obviously have a factor. I use a white transluscent plastic for screens to give sensors a solid background. Like shooting, consistent conditions. You can use LEDs to give the optical sensors a more consistent and predictable light source.

This.

I use a Competition Electronic Prochrono digital.  Mostly airgun pellets these days, very small.  Just the right amount of light is crucial to consistent readings with no errors.

Remind me of project to have a powe supply for the LEDs and the chrony. Plan to use a 7812 reg for the LEDs and 7809 for the chrony with a sealed lead acid batt to power them.

The wires to the left of the shades is the power supply for the LEDs. I'll play around with it in my yard and use a rubber band. Previous tests have shown 68.2 FPS. I'll lay a thin cardboard over the LED lights, then cover with a dark fabric and secure with binder clips. Mwahahaha...

The wires to the left of the shades is the power supply for the LEDs. I'll play around with it in my yard and use a rubber band. Previous tests have shown 68.2 FPS. I'll lay a thin cardboard over the LED lights, then cover with a dark fabric and secure with binder clips. Mwahahaha...

I was planning on using some window screen, on the sides, to block out light, yet allow air flow, so the wind doesn't knock it over.

I do have spare screen in my garage. I tried to reproduce the error in my yard in full sunlight. The chrono worked okay in both full sunlight and shade. It passed the rubber band test until I finally lost the rubber band. Annoying because I've probably thrown away more rubber bands than I kept.

I do have spare screen in my garage. I tried to reproduce the error in my yard in full sunlight. The chrono worked okay in both full sunlight and shade. It passed the rubber band test until I finally lost the rubber band. Annoying because I've probably thrown away more rubber bands than I kept.

I dont see how rubber bands fit into the picture

Ha, I shoot the rubber band through the chrono to see if it works. Seems to work better than throwing rocks. I was able to measure a few passes in full sunlight. I guess it's hit or miss at the range, literally.

Seems to work better than throwing rocks.

No way I would be able to throw a rock that accurately. 

Now, a pea shooter.....But, do they even make those these days?  Probably requires a permit and fingerprinting.

I saw them at SEC on Saturday but probably do need a permit.