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Posted: Wed Jan 13, 2010 11:19 am
Would you guys know what replaced these components?
7474 TTL dual D-type flip-flop
7490 TTL decade counter
7805 +5V regulator (TO-220 pkg)
Posted: Wed Jan 13, 2010 11:36 am
these parts are still in use and available
7474 TTL dual D-type flip-flop - this part might beguin with 74LS* (74LS7474)
7490 TTL decade counter - same thing with this part. (74LS7490)
7805 +5V regulator (TO-220 pkg) this part typically beguins with "LM" (LM7805)
theres other vareitys of part numbers that are all the same parts.
hope this helps you,, good luck
Posted: Wed Jan 13, 2010 2:01 pm
that helped quite a bid.
Posted: Wed Jan 13, 2010 5:04 pm
What really replaced those chips are the 74HCxxx and 74VHCxxx families. Stronger, faster and less current consumption with a cleaner output pulse.These familys follow the same EIA numbering system and almost always are pin for pin replacements.I don't think any new design would even look at the 74XX family any more. The 7805s are just about anywhere you look. May have various prefixes such as MC or LM.
Posted: Wed Jan 13, 2010 6:34 pm
Well, I did search for them and seemed like no one carries them or are out of them. It was this late evening that I realized nowhere I could see Jameco website, Google just does not return anything from Jameco, the only supplier that has them.
Posted: Wed Jan 13, 2010 7:49 pm
Jameco 7805 search page
Hope you can get into Jameco's site this way.
Posted: Wed Jan 13, 2010 8:03 pm
I believe the 7805 (and similar members of the family) were originally developed by National as the LM340T-5.0 (change the number after the hyphen for the different voltages: 8, 9, 12, 15, 24) while the negative version, the 7905 was originally the LM720T-5.0, etc. Just another avenue of search (and history), however as mentioned, they're common as pea gravel in electronics catalogs.
Posted: Thu Jan 14, 2010 1:45 pm
Google just does not return anything from Jameco, the only supplier that has them.
Here are the 7805's at Mouser:
http://www.mouser.com/Semiconductors/Po ... 05&FS=True
And from DigiKey (this link shows more package options, etc - but mouser's site will do the same)
http://search.digikey.com/scripts/DkSea ... 290&k=7805
Hope it helps,
Posted: Thu Jan 14, 2010 4:02 pm
I have 15 different retailers catalogs I keep book marked from the largest companys to the smallest. Every one carrys these chips. You could walk thru them blindfolded and stumble on them every step of the way. ----OR, am I missing something here such as you are committed to only the 74xx TTL family?
Posted: Thu Jan 14, 2010 6:45 pm
This way, I searched google for those chips and most of the sites that would show them would be UK sites! If I went to digikey they would be out of them and several others. I am not making it up
That is why I posted.
Posted: Thu Jan 14, 2010 9:12 pm
But what I was asking- are you committed to TTL or can you use the same chip from another family?
Posted: Fri Jan 15, 2010 7:24 am
Sorry, I missed that point, no I am not committed and so it can be any other. I did try to see if I can find similar but I have not used it for so long I don't really know which ones would fall into that same category. If you know of the other ones I appreciate your help.
Posted: Fri Jan 15, 2010 9:40 am
You need a 'D' flipflop(7474, a decade counter (7490) and a 5 volt 1 watt regulator (7805).
The 74xx series falls into many family groups that differ in class by a two or 3 letter insertion following the 74 label. In TTL this would be none,S,LS generally. In more modern familys, this would be C (5 volt operation), HC( Fast 5 Volt operation) and VHC (very fast 5 volt operation). there are others with designations for low voltage operation (3.3 volts) and transistor/mos combos. There will be dozens of suffixes at the end of which most are of little importance to the home hobbiest. Just look at the lowest priced and thru hole spec (if that is what you are after). Also the CD4000 and MC4000 families have the same chips you want. Just look at the last two numbers that correspond to your selections. These chips will operate from 3-15 volt supplys, but are slower than the aforementioned ones. 7400 series - good to 25 MHz; 74HC00 - good to 70 MHz; 74VHC series - good to 150 MHz (actually I have used these at 180MHz);4000 series - slowest of all. Any of the chips should be less than a dollar apiece. I always buy 3 of any given chip -1 for use;2 for an "oops" and 3 for future backup and to help justify todays ungodly postage rates
Need more help?
Posted: Fri Jan 15, 2010 12:03 pm
You right about the shipping. It takes planning to put together the necessary components before I can even purchase any of them. It always delays my stuff and everything I am trying to do. I’ll look into those you described and see how slow. I am trying to build some small projects so I can get going and hopefully I can show it to my son to get him exposed, hopefully he might get into it.