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Sets, Parts and Service Information Wanted (private buyers only, no swaps) If you need help obtaining components, sets or equipment, post a message here. Private buyers only - no traders. No swaps.

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Old 5th Jul 2020, 9:40 am   #1
line sync
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Default Where can I buy SN74 series chips?

Can any one recommend a supplier for SN74 series chips ?
I know RS and Farnel sell them buy they have a very limited range.

Robin
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Old 5th Jul 2020, 9:43 am   #2
ValvoStef
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Default Re: Where can i buy SN74 series chips

Try Rapid Electronics or eBay.
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Old 5th Jul 2020, 10:08 am   #3
SiriusHardware
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Default Re: Where can i buy SN74 series chips

Robin, if you mention the specific types you need someone here may have some.
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Old 5th Jul 2020, 10:10 am   #4
barrymagrec
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Default Re: Where can i buy SN74 series chips

Do you only want Texas chips or do you just want 74 series.

Many variations,, L, LS, ALS, S etc.

Package, DIL, SM, Ceramic etc
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Old 5th Jul 2020, 10:55 am   #5
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Default Re: Where can i buy SN74 series chips

Any good branded names ok.
LS types & DIL.
Haven't made a list yet.

Robin
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Old 5th Jul 2020, 11:09 am   #6
mickm3for
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Default Re: Where can i buy SN74 series chips

Hi Jabdog electronics has most types http://www.jabdog.com/ Mick
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Old 5th Jul 2020, 11:12 am   #7
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Default Re: Where can i buy SN74 series chips

SN prefix is proprietary to Texas Instruments inc. Other makers made fully compatible parts (Motorola, National Semiconductor etc etc.

If there are letters after the 74, these are very important. Not all are compatible with others... some are even CMOS.

No letters immediately after 74 means plain original TTL. Then along came various improved families with added letters. High speed (high power!) Low power, advanced low power, Schottky, low power schottky, CMOS, High speed CMOS, Advanced CMOS all have differences in speed, power and driving/loading characteristics.

You had to live through the era as a designer to know how to mix and match all the families!

David
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Old 5th Jul 2020, 11:22 am   #8
barrymagrec
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Default Re: Where can i buy SN74 series chips

RS seem to have a pretty fair range of the more usual types:-

https://uk.rs-online.com/web/c/?pn=1...m=74ls&sra=oss
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Old 5th Jul 2020, 11:32 am   #9
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Default Re: Where can I buy SN74 series chips?

There are also the 54xx and 64xx series, functionally the same as the 74xx series but more robust and useable over greater temperature ranges and therefore more expensive. At Plessey, we used them in stuff designed for military/aerospace applications. My first encounter with TTL was in 1967 when I was a student working at Plessey for job experience and had to build a breadboard circuit using a mixture of 54xx and 74xx TTL. It had a 5V supply for the TTL and a 28V supply for an electromagnetic indicator. No prize for guessing who got them transposed! All the 74xx died, all the 54xx survived unscathed.
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Old 5th Jul 2020, 1:39 pm   #10
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Default Re: Where can I buy SN74 series chips?

Cricklewood Electronics list a large range of such devices
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Old 5th Jul 2020, 1:51 pm   #11
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Default Re: Where can I buy SN74 series chips?

Watch out that some electrical specs for the 54 prefix military spec types can be different and there can be compatibility issues. Check these on an individual basis not a family basis.

David
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Old 5th Jul 2020, 7:28 pm   #12
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Default Re: Where can I buy SN74 series chips?

I suppose my collection of chips is another thing I will never now use.

So, 12 various sized boxes of mostly DIL chips. There is absolutely everything here, lots of TTL, some CMOS, processors, DRAM, SRAM, peripherals etc etc. It is all pulls, so used but laboriously pulled from sockets.

Guess about 30kg in total.

Too much to try and pack and post, collection only, FOC.
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Old 5th Jul 2020, 8:29 pm   #13
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Default Re: Where can I buy SN74 series chips?

Ah, had a reply for the chips, but not the OP, better make sure he doesn't want them first.
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Old 5th Jul 2020, 9:03 pm   #14
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Default Re: Where can I buy SN74 series chips?

Hi Woodchips
Thank you for the offer of the chips but I don't go anywhere near grantham so please feel free to let the other person have them.
A very generous offer .

Robin
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Old 6th Jul 2020, 7:38 am   #15
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Default Re: Where can I buy SN74 series chips?

You should ask whover takes them, as a "condition of sale" (= gift), that they catalogue the collection in Excel and post it back here!

John
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Old 6th Jul 2020, 12:38 pm   #16
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Default Re: Where can I buy SN74 series chips?

There must be 20,000 chips, I wouldn't do that!

Not to say that they won't be plagued by requests for them.
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Old 6th Jul 2020, 6:28 pm   #17
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Default Re: Where can I buy SN74 series chips?

Thanks for all the reply's guys , I`d like to ask a few things.
The project I`m wanting the chips for are arcade video game boards from the early 1980`s.
Although 90% of the chips are the LS versions , the manufacturer does list some of them as the plain TTL version.
Now does this mean I can fit an LS version in place of a plain TTL version ?
I have fitted 7474`s in place of 74LS74`s and they work.

Robin
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Old 6th Jul 2020, 7:50 pm   #18
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Default Re: Where can I buy SN74 series chips?

The original devices were very power-hungry and required an accurate 5V supply for reliable operation. I never got to use the later low power devices.

I used to have a power supply intended for use with TTL, rescued from a skip at Marconi, that I used to use as a door stop: 5V at 20A, stuffed with large electrolytics. I am afraid it got left behind during an office move.

Last edited by emeritus; 6th Jul 2020 at 7:54 pm. Reason: Typos
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Old 6th Jul 2020, 8:03 pm   #19
barrymagrec
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Default Re: Where can I buy SN74 series chips?

Quote:
Originally Posted by line sync View Post
Thanks for all the reply's guys , I`d like to ask a few things.
The project I`m wanting the chips for are arcade video game boards from the early 1980`s.
Although 90% of the chips are the LS versions , the manufacturer does list some of them as the plain TTL version.
Now does this mean I can fit an LS version in place of a plain TTL version ?
I have fitted 7474`s in place of 74LS74`s and they work.

Robin
Mostly an LS version will replace a plain - not always however, there are some instances where they have to be the original type.

Early eighties was well into the time of LS being the norm so be careful when substituting families.
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Old 7th Jul 2020, 9:12 am   #20
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Default Re: Where can I buy SN74 series chips?

Quote:
Originally Posted by line sync View Post
Although 90% of the chips are the LS versions , the manufacturer does list some of them as the plain TTL version.
Now does this mean I can fit an LS version in place of a plain TTL version ?

Robin
The original 74 and low-power Schottky 74LS series TTL are generally compatible. Voltage levels and speeds are similar but 74LS uses less power. When mixing you need to take care about fan out.

An original 74 series with totem pole output such as the SN7400N has a low-level output current (IOL) of 16mA which can drive up to 10 inputs of the same family (IIL 1.6 mA).

A standard 74LS series with totem pole output such as the SN74LS00N has a low-level output current (IOL) of 8 mA which can drive up to 10 inputs of the same family (IIL 0.8 mA) but only 5 inputs of the original 74 series.

David
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