IC for shutter-speed tester

[Paul Whiting]

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

 

[audioguru2]

The "N" is the type of package. The LM339 in your photo was made by National Semiconductor and has pins so its package is called "N".

I do not know what Radio shack sells because they are gone from Canada. Make sure it is in a package that fits in your IC socket. 

 

[Paul Whiting]

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

 

[Paul Whiting]

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

 

[audioguru2]

www.radioshack.com does not list an LM339 IC. Maybe some US stores still have some. I hope the one you found is a real one and not a cheap Chinese fake one. Look at the datasheets of the LM339 at www.datasheetarchive.com where they have an entire list of manufacturers who make it. Find the manufacturer's symbol for the one sold at Radio Shack to make sure it is a real one.

When Radio Shack was in Canada they sold some cheap Chinese junk and cell phones at very high prices. They left Canada and sold to Circuit City who sold to Bell Canada and now they specialize selling Bell Canada cell phone contracts and some audio products. They are called The Source now. 

 

[Paul Whiting]

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?

 

[audioguru2]

If the IC is bad then it might damage the power supply. Then the damaged power supply might burn down your house unless it is fused.

 

[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