The ratio of dark to light current is hard to measure, but I can infer I'm getting about 150 nanoamps dark current, and 595 nanoamps with a solid object in front of the detector. What light current I get with reflected light from smoke I don't know since I've never been able to trigger it with smoke yet.. Remember this arrangement is based on pulsing the IR emitter at high amps for brief periods. I tried an arrangement with a phototransistor and an LED powered with DC yesterday, still no luck. The DC led was probably not bright enough to do any good. All of these have worked fine in detecting solid objects. ----- Original Message ----- From: "David VanHorn" To: "Lawrence Lile" Sent: Wednesday, December 20, 2000 9:12 PM Subject: Re: [PIC]: Sssssssssssmokin' > > >Had a chat with the OPTEK engineer I'm working with, and this is the > >arrangement he recommended. Said that the reversed biased LED was much more > >sensitive than the photologic module I was working with earlier. So far, > >you can't prove it by me. > > Phototransistor. > Also, what's your current ratio, target to no-target? > -- > Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body