Homebuilt Phototransistor Chronograph

[rp181]

post what kind you ordered. Some phototransistors only work with IR, and may have a IR transparent epoxy(opaque to everything else). If so, you need IR LED's, datasheets usually specify matching LED's. If not, and normal LED will work depending on distance (farther= brighter).
Jimmy's page is the best I have seen, but here is mine:
http://rp181.110mb.com/index.php?p=1_24 ... speed-trap

[inonickname]

post what kind you ordered. Some phototransistors only work with IR, and may have a IR transparent epoxy(opaque to everything else). If so, you need IR LED's, datasheets usually specify matching LED's. If not, and normal LED will work depending on distance (farther= brighter).
Jimmy's page is the best I have seen, but here is mine:
http://rp181.110mb.com/index.php?p=1_24 ... speed-trap

http://www.altronics.com.au/index.asp?a ... m&id=Z1613

[rp181]

The VERY limited datasheet doesn't say much, but it says "packaged in a special dark plastic". That means it is probably only transparent to infrared, you may need infrared diodes or a strong light source (no frequency specific, a broad range, use a normal heated filament lamp rather than an LED). When you get it, if the plastic is clear, try normal LED's. If the plastic is dark, normal LED's probably won't work.

[jimmy101]

Like rp181 said. Any incandescent will probably work OK. Fluorescents are out. Sun light will probably be the best thing other than IR LEDs.