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Registered Member #1774
Joined: Wed Oct 22 2008, 02:51AM
Location:
Posts: 135
As the title says I need to know what I should be looking for to get the best responce time for my coilgun, I.e. sensitivity (high mW or low?). Because I have purchased 20 high quality 880Nm IR emmitters @170mW output. Does it need to be the three pin kinf or the two pin? If you know of a specific part number that would be great.
Registered Member #968
Joined: Fri Aug 24 2007, 04:54PM
Location: Norman, Oklahoma
Posts: 104
The diode should have 2 pins. Make sure it is actually a photodiode and try to match the peak sensitivity to your emmiters, such as Fairchild's Part# QSD2030. Other than that you will have to pick package size and viewing angle.
Registered Member #1774
Joined: Wed Oct 22 2008, 02:51AM
Location:
Posts: 135
Since that Is the peak wavelength should I try and get higher rated sensors (ie I saw some 940nm peak ones)? Also what is the sensitivity they have (in the link) . And would that be a suitable one, Because its responce time is 2.5nS
Registered Member #968
Joined: Fri Aug 24 2007, 04:54PM
Location: Norman, Oklahoma
Posts: 104
No you will want to match the sensors peak sensitivity to the peak output of the emitters. Any difference in these two numbers will decrease efficiency of your photogate.
2.5ns is very good but you will prefer 880nm photodiodes.
Registered Member #1774
Joined: Wed Oct 22 2008, 02:51AM
Location:
Posts: 135
Heres the emitters I got, . I just assumed they were good since the retail price for them is NZ$5.90 each. I wont be able to get receivers that are rated at 880nM because they cost over NZ$40 each! The next closest is 900nM but they cost $14 each... the closest cheap ones are the 940nM ones I posted before, will that be a problem if I used them?
Registered Member #968
Joined: Fri Aug 24 2007, 04:54PM
Location: Norman, Oklahoma
Posts: 104
It won't be a problem to use the 940nm ones. If you look at Figure 6 on page 3 of the datasheet, that photodiode is still slightly more than 90% as sensitive at 880nm as at the peak sensitivity(940nm)
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What to look for in photodiodes for coilgun optics.
