Paul Whiting

Well, I do thank you for all your efforts... I'm afraid I'm in deeper water than I care to navigate! I may have to put this project aside for now. It may end up with a friend more knowledgeable than I, and who thinks he can fix it. Again, my sincere thanks! Best regards, Paul Again, being new here, I'm not familiar with the protocol. Do I need to mark the thread as closed, or does the sysop do that, or...? Paul

Well, this am I had to go pick up a prescription and RS was just a few blocks away. The clerk and I looked through the clear plastic container and the IC turned out to be a LM339N, with the "N". It was simply mislabeled, without the "N", on the package. I hadn't received your response yet but at $2.49 I figured I might as well get it. When I got home I saw your post... unfortunately it is made in China. But on the chip was the Texas Instruments logo (that could be bogus of course) and this number: 2BML5REE3. I looked up the data sheet on the website you mentioned, thank you for that. However I couldn't find that exact chip under Radio Shack, but it was under Texas Instruments, manufactured by Fairchild. The word "buy" was after LM339N so I guess that means it's ok. I couldn't find the 2BML5REE3 number though. I'm willing to gamble that small cost... can I damage anything in the rest of the circuit if the chip is a bad one?

error in the phrase: "it is not surface-mounted and has a socket." Should be: "uses a socket".

Very helpful, thank you! (not sure what you meant by "gone from Canada"... I take that to mean you're in Canada and Radio Shack doesn't have stores there now?) Anyway... the IC at Radio Shack has no "N", but it looks to have the same package as my existing and possibly damaged IC, ie it is not surface-mounted and has a socket. Maybe the manufacturer of the one at Radio Shack simply forgot the "N". If it's the same electronically I guess I can't hurt anything by trying it. It's only $2.49. I'll take my device along and make another trip to our local store today to make sure it's the same package. And actually, the salesperson said she suspected the "N" was simply the physical aspects of the IC. She had several LM339's on her computer screen, each one with a different suffix and a different package. Mine does have pins and I do have a chip puller. Thanks again, I'll let you know if my shutter-speed tester works again. They're not available any more, now that most cameras are digital... am testing the shutter on a 50+ year old film camera! Paul

Hello, I'm brand new here, so I hope I picked the right forum! I'm working on a shutterspeed tester... it's already built, but I have reason to believe I may have zapped its IC. The IC is a LM339N - I can find a LM339 (no "N") at my local Radio Shack. Is that N important? If so, can anyone suggest a site to buy one? Most of the hits I get in a web search require buying several at once, and sometimes have a high minimum order. If anyone here has the IC I need I'd be happy to buy one from you! Thanks all, Paul