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ProChrono light sensor?


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#1 ericw

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Posted 29 March 2012 - 07:32 AM

I'm getting a ProChrono digital chronograph and thought I would make my own light setup for indoor shooting. I want to match the light color (wavelength) sensitivity peak of the sensors with something close in an LED light strip. Anybody know what the device part number is for the one used in the prochrono?



#2 DaveL

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Posted 29 March 2012 - 03:56 PM

I have a CED chrony with indoor light strips powered by LEDs. The LEDs are behind a diffuser of milky-white plastic and are positioned exactly above the front and rear sensors. That positioning is critical to ensure the distance between the two light sources equate to the distance used in the chrony's calculation of velocity. I would say that any LED that approximated daylight colour temperature would be OK, that is to say, erring slightly on the yellow side rather than the blue. It depends on what your sensor reacts to. You might be able to get away with red, for example.

Try Mouser or Digikey and have a look at their spec sheets on 5mm discrete white LEDs.

Don't forget, you'll have to power them. Unsmoothed DC will be good enough and they can be joined in series, preferably with a series resistor. You could, in fact, have them running at switchable illumination levels. Without experimenting, you can't determine just what level of current will give you the ideal illumination of the sensor(s) but with modern LEDs, chances are that a current of 10mA would be adequate. You will need to run the chains of series LEDs in parallel. I can help you further, should you wish, by contacting me directly.

DaveL

#3 ericw

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Posted 29 March 2012 - 09:16 PM

Thanks for the info. I'm an electronics engineer so no problem with any of that. Most photodiodes or transistors are sensitive to IR wavelengths but was just wanting to match the light source wavelength to the sensor peak sensitivity wavelength since I have to buy them anyway. I made a choice to not just homebrew my own chronograph after playing around with the optics, getting something to work by looking at pulses from sensors on an oscilloscope but then the thrill was gone .. and it is actually cheaper to just buy it. The prochrono indoor lighting package they sell would be OK but is too expensive for what it is. The same is true for the digital interface they sell .. for these i am rolling my own solutions. It seems the accessories are where the money is made.. like ink for printers. I'll post some info on the results when done.

#4 DaveL

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Posted 29 March 2012 - 11:21 PM

Hey, man! Talk about teachin' granny to suck eggs! Wheeze.gif I'm glad I didn't hammer on about it. Most of these rigs use IR diodes, so I'd head that way rather than the daylight whites, the IRs are cheaper, but stick a green or red one in circuit so you at least know the power is on LOL!

I went to do the smoke test on some stuff I'd finished building this evening, switched on, no bang, no sizzle, no smoke, NOTHING! Hells bells, what the heck have I done wrong? beg.gif Panic - be calm, deep breath, oooommmm, deep breath ooommm, deep breath, ooooommmm, beggar it, I've switched on the wrong PSU! poster_oops.gif withstupid.gif

amen.gif DaveL

#5 Jon

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Posted 30 March 2012 - 08:58 PM

Must be old age Dave.

Good choice on Prochrono, i nearly bought one but as you said by the time you have the extras you could have the best the CED M2. I have the infra red, weird shooting in pitch black but gives exactly the same readings even when fluorescent of all things is over head.





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