Low Buck Infrared for CED Chronograph

[theinfamouselguapo]

Well it was bound to happen. First decent weather but a few clouds and I dumped about one shot out of each string. Not enough to make it a wasted trip, but enough to make me go back and rethink things a bit.

CED uses an infrared sensor. Both indoor, and outdoor, measurements can actually benefit and improve from using a steady, reliable infrared source. Take a look at the link.

http://www.airrifle.co.za/showthread.php?t=16969

I'm waiting on my LED's at this point. They ran me a total of $6.50 for fifty of them. Perspex is a bit pricey and hard to come by where I live so I'm either going to use plexiglass or Lexan. The latter is still a bit high but much easier to work with.

Not all infrared LED's are created equal. 940nm is a requirement. The angle of divergence needs to at least be 20 degrees. The current ratings can vary a little so that means you might need to adjust the limiting resistors just a bit as well.

If there's any interest in this I'll post the rest of the details as mine gets closer to completion.

[Walter Laich]

would like to see how this project goes

walt

[Reloader06]

Me too.

[theinfamouselguapo]

The original LED's used by Sighter are from a company called "Bright Lite", which is in China. I could not find a source in the US that deals in small quantities so I am substituting a different part. The substitute part is 940nm, has a higher output but a more narrow, 25 degree, half power beamwidth.

Here are the specs and the company from which I ordered -


www.vishay.com/docs/81014/tsal7400.pdf

http://www.taydaelectronics.com


There are a couple of different ways you can put this together. I am sticking mostly with the original skyscreen design. Because of the shape of the posts I'm going to reuse them. But the tops I am going to clone from Lexan.

One of the untried things from Sighter's build was a diffuser lense. If I can get this to work well enough I can reduce the number of LED's which will cut current drain back and extend battery life.

If there are any other features that you can think of that should go into this let me know and I'll try to work them in.