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Peter Bertini
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Post subject: 74LS02 iCs getting scarce.. Posted: Sep Fri 10, 2021 4:56 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 22694 Location: Somers, CT
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I needed several 74LSxx variety ICs for a board repair. I was surprised to discover the DIP packages were out of stock at Mouser and Digikey! Factory backorders, and they are not stocking huge quantities as they did the past. Jameco had them in stock. I'm also noticing the supply of MRF-150A devices are also slowly fading from view 
_________________ Just because it can be done doesn't mean it should be done.
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Tubologic
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Fri 10, 2021 5:42 pm |
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Joined: Jul Mon 08, 2013 2:48 pm Posts: 1016
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"Trough hole" packaged parts are no longer used in the industry and were all replaced by SMD devices. Demand has collapsed and suppliers have adapted their stocks accordingly and/or stopped manufacturing these parts. Nearly ALL "through hole" electronic parts are now considered as "obsolete" and supply will dwindling in the years to come. Also, 74xxxx series logic chips are considered as "prehistoric" parts and won't be remanufactured again. There should be still millions of these in dormant stocks at various parts suppliers warehouses but since there's is no demand and turnover is very low they'll very likely end up scrapped one day.
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Rich, W3HWJ
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Fri 10, 2021 5:52 pm |
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Joined: May Tue 30, 2006 4:46 pm Posts: 11381 Location: Santa Rosa, CA
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Airway Radio Fan
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Fri 10, 2021 7:05 pm |
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Joined: May Tue 05, 2020 5:08 pm Posts: 162 Location: Youngstown, OH
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SHenion
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Fri 10, 2021 7:08 pm |
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Joined: Feb Wed 07, 2018 6:52 pm Posts: 1273 Location: Stone Mountain, GA
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I'd be substituting 74HCTxxx parts. Much newer, lower power and still available.
They will work except when use with R/C delays (analog circuits.)
As an engineer, I stopped using 74LSxxx in the early '80s. HCT took over very fast at the time.
_________________ Scott. Powered by infinite improbability drive.
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Chris108
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sat 11, 2021 1:17 am |
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Joined: Jun Fri 19, 2009 6:34 pm Posts: 11921 Location: Long Island NY
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There are hundreds of thousands of semiconductors that were once popular but are now obsolete, forgotten, and unavailable except through surplus channels. 74LS small scale logic chips in DIP had their day and for the most part are following the pattern towards oblivion. 74LS02 in DIP is probably seldom used if at all in new designs, but if you just need a few to keep a piece of gear going it appears there are still tons of them for sale on eBay.
_________________ "Hell, there are no rules here--we're trying to accomplish something!"
Thomas A. Edison
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Pbpix
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sat 11, 2021 1:36 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 23901 Location: Haledon, NJ, usa
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_________________ To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind. -Emerson
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Scott
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sat 11, 2021 1:06 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 7309 Location: Montvale NJ, 07645
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Pbpix wrote: Thanks Peter. I never heard of them and I just bookmarked them.
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Jim Dutridge
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sat 11, 2021 3:52 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 8155 Location: Toledo, Ohio
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_________________ Jim KE8GMW --------------------- I have flying monkeys and I know how to use them.
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threeneurons
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sat 11, 2021 5:09 pm |
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Joined: Jul Sun 17, 2011 1:11 am Posts: 4571 Location: Tehachapi, CA - Bottom end of the Sierras
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Peter,
I have:
2 74LS02, 2 74ALS02, 1 74F02, and 15 74HCT02 ICs.
You can have any, or all, of them for postage.
All plastic DIP. I have no need for them. Bought & used them decades ago. These are just leftovers. PM me, if interested.
Surface mount sales, exceeded "through hole" sales ~1995. That's more than a quarter century, now. In addition to that, 3.3V logic replaced 5V logic, too, many years ago.
The only old logic family, that's still got some use is 4000 series CMOS, mostly because of it versatility. It can operate with supplies ranging from 3V to 18V.
When it comes to most logic circuits, programmable logic (PLDs to FPGAs) has mostly supplanted fixed logic in most areas. With existing logic, whole bus buffers, are used more than gate packages. Also a lot of custom chips, if the production volume justifies it.
_________________ Life is like a roll of toilet paper - The closer you get the end, the faster it goes - A.E. Neuman
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Pbpix
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sat 11, 2021 6:49 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 23901 Location: Haledon, NJ, usa
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Scott wrote: Pbpix wrote: Thanks Peter. I never heard of them and I just bookmarked them. Yeah.. they specialize in maintaining a supply of discontinued or hard to find semiconductors.. and they are an authorized distributor. I received some fake/counterfiet OP-275 op-amps via some Asian ebay seller ... who actually admitted they were fake and refunded me. I only determined they were fake when the current draw per chip was twice that specified on the Analog Devices datasheet. I contacted Analog Devices. who makes the op-275, to ask if there was any foolproof way of detecting fakes. The sales rep told me that counterfiets were the biggest problem in the industry and the only/best way to avod them is by ONLY purchasing from authorized distributors like Newark, Digikey, Mouser etc. And from other trusted authorized resellers such as Rochester ! That's how I found them.
_________________ To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind. -Emerson
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Airway Radio Fan
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sun 12, 2021 1:07 am |
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Joined: May Tue 05, 2020 5:08 pm Posts: 162 Location: Youngstown, OH
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Nasco is another broker we use at work. They have some fancy x-ray technology that allows them to examine the dies inside the device to detect counterfeits. We have great results with them on obsolete chips (but they aren't cheap)
_________________ Interested in buying Airway branded radios and parts from Toledo, Ohio made in the 1920s.
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Peter Bertini
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Sun 12, 2021 1:48 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 22694 Location: Somers, CT
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Thanks for the offers, but as I mentioned Jameco had a large supply of them for a decent price. What was surprising is that all of the other 74L$xx devices were in stock and available and just the LS02 chips were backordered. I'd rather not buy semiconductors on eBay since most of them come from China despite the seller's shown location. The radio is a JRC transmitter and I'd rather keep it original since it is a fairly scarce transmitter.
_________________ Just because it can be done doesn't mean it should be done.
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Usually Lurking
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Mon 13, 2021 12:47 am |
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Joined: Jan Tue 16, 2007 7:02 am Posts: 5239 Location: Lexington, KY USA
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Attachment:
46287.jpg [ 14.11 KiB | Viewed 1643 times ]
https://www.jameco.com/z/74LS02-Major-Brands-IC-74LS02-QUAD-2-INPUT-POSITIVE-NOR-GATE_46287.html It's interesting that Jameco's illustration for the 74LS02 they are selling shows a 8506 date code. That might be just what you get, too. It's safe to say that Motorola doesn't make those new any more. Ted
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SHenion
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Mon 13, 2021 1:04 am |
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Joined: Feb Wed 07, 2018 6:52 pm Posts: 1273 Location: Stone Mountain, GA
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Usually Lurking wrote: Attachment: 46287.jpg https://www.jameco.com/z/74LS02-Major-Brands-IC-74LS02-QUAD-2-INPUT-POSITIVE-NOR-GATE_46287.html It's interesting that Jameco's illustration for the 74LS02 they are selling shows a 8506 date code. That might be just what you get, too. It's safe to say that Motorola doesn't make those new any more. Ted Some of the parts Jameco sells are pulls out of boards. Others are old stock. Ordered some one-time programmable chips and they were already programmed. Like buying used flashbulbs. Their printed catalogs used to show the catalog number for used parts or old stock in a different color. Seems they now just show them as "various manufacturers". Used to use Jameco a lot and still like them for some things but I wish they were more transparent.
_________________ Scott. Powered by infinite improbability drive.
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Tubologic
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Mon 13, 2021 1:33 am |
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Joined: Jul Mon 08, 2013 2:48 pm Posts: 1016
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SHenion wrote: Some of the parts Jameco sells are pulls out of boards. Others are old stock. Ordered some one-time programmable chips and they were already programmed. Like buying used flashbulbs.
Exactly. Once burned, fuse type PROM's can't be erased or re-programmed. Pullouts are useless.
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Chris108
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Mon 13, 2021 12:07 pm |
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Joined: Jun Fri 19, 2009 6:34 pm Posts: 11921 Location: Long Island NY
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If the goal is to keep a vintage transmitter on the air, you may be better off with a NOS or good used "pull" device, rather than a freshly manufactured one anyway. Not for nothing, the masks, production machines and in some cases whole factories that made those chips 25, 35, or 45 years ago simply don't exist any more. Where the chips are still produced they are done with today's processes and equipment, using masks and materials suitable for today's production. So even though the part numbers are the same, the chips themselves probably are not. Unless you have compared the data sheets for the old chip to the new one, it is possible that there could be subtle differences in timing or voltage levels that can get you into trouble. A new chip that switches ten times faster than the old one is not necessarily an advantage if the latency was necessary to keep the board from latching up.
_________________ "Hell, there are no rules here--we're trying to accomplish something!"
Thomas A. Edison
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wazz
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Mon 13, 2021 7:40 pm |
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Joined: Jun Wed 08, 2011 2:33 am Posts: 13096 Location: Ohio 45424
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Well what did we do when the drugstore and Radio Shack stopped selling tubes? They are still out there, not where they used to be.
_________________ Reddy Kilowatt says; You smell smoke? Sorry about that!
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Tim Tress
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Tue 14, 2021 1:21 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11693 Location: Beaver Falls, PA. USA
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The old chips and germanium transistors are out there; I found the obsolete Motorola ECL chip that I needed for my Heathkit AJ-1510 on Ebay. Wasn't cheap, but whaddaya gonna do...
_________________ Tim KA3JRT
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Peter Bertini
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Post subject: Re: 74LS02 iCs getting scarce.. Posted: Sep Wed 15, 2021 5:26 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 22694 Location: Somers, CT
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The worst chip I ever tried to locate was a 74S90N. They were made for an extremely short run. I wanted one for a homebrew frequency counter since it was about the fastest decade counter at the time... I don't see anyone selling them.
_________________ Just because it can be done doesn't mean it should be done.
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