Hi Gus, I went through this confusing topic sometime time ago. It would appear that they make LEDs to provide two separate functions. One is as an indicator where you are interested in light intensity. The plastic around the LED helps to focus the light in a narrow direction. (Usually the thru hole type, 3mm, 5mm, etc). These have their specs given i= n candela or viewing light intensity at a distance. The second function is as a replacement light globe. These units (often SMDs) have their specs given in lumens, which is more about how they illuminate a particular area at a particular distance. For your project, the narrow viewing angle, indicating LEDs will be more useful. Paul Owen Jasdip Message: 1 Date: Sun, 5 Apr 2015 22:17:27 -0600 From: 99guspuppet Subject: [EE]: LEDs ...SMT versus through hole To: piclist@mit.edu Message-ID: <76D34F9A-4CE2-41A3-B306-9AB6097EA705@nope9.com> Content-Type: text/plain; charset=3Dus-ascii I found some CREE LED product at Mouser. C503B-AAN-CY0B0251 http://www.mouser.com/ProductDetail/Cree-Inc/C503B-AAN-CY0B0251/?qs=3D%2fha= 2py FaduikwXp24CmdxMq1GICdnzBgcXgvOzTm4AXFnV0CcevnzJNQ6PWF7qwK This is a through hole Amber LED rated at 13000 mcd at 20 ma. ( there seem= s to be some variance in output specifications depending on where I look in the data sheets ) I have not been able to find an equivalent part that is SMT. Am I missing something ? Is there reason why SMT LED devices would be a whole different world ? I am using this LED in signage ( hand-held ) that will be read in the range of 5-20 meters. The sign will be pointed at cars and pedestrians. Would a viewing angle of 15 degrees that yields a diameter of visibility of ( 20 * ..26 ) 5.2 meters at 20 meters work out well ? Or would 30 degrees ( 20 * ..0.5 =3D 10 meters ) be a better choice ? Gus in Denver ------------------------------ -- http://www.piclist.com/techref/piclist View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist End of Piclist Digest, Vol 129, Issue 6 *************************************** __________ Information from ESET NOD32 Antivirus, version of virus signatur= e database 11433 (20150406) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .