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74XX

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alec_t

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Welcome to ETO!
Someone, somewhere in the world will be using them, if only for repairing old equipment.
 

kubeek

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I don´t think anyone still uses the original series (or maybe just for homebrew stuff from old stock), but the new families such as HC, LVC etc. are widely used.
 

Nigel Goodwin

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the new families such as HC, LVC etc. are widely used.
Don't know about 'widely' - the advent of micro-controllers has pretty well made most logic chips obsolete - why use 20-30 logic chips when a single micro-controller will do the job better and easier?.

There are obviously a few exceptions, with logic chips often used as port extenders or drivers.
 

schmitt trigger

Well-Known Member
I would say, not used for any new products which you intend for sale...it would be cost prohibitive.

Now, I'm sure some retro-enthusiasts are still building digital clocks (or even more complex projects) using 74xx chips and red 7-segment LED displays somewhere in the world.
 

kubeek

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Don't know about 'widely' - the advent of micro-controllers has pretty well made most logic chips obsolete - why use 20-30 logic chips when a single micro-controller will do the job better and easier?.

There are obviously a few exceptions, with logic chips often used as port extenders or drivers.
Most designs i have seen need a few invertors here and there, an AND gate, a latch, few level shifters etc. Although nowadays they are mostly used in those small one- or two-gate packages, instead of a huge SO14.
 

JimB

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I recently used a 74HC08 in a one off project.

I used it as an interface between a PIC and a motor speed control module.
There may have been other ways to do it, maybe it could have all been done in the PIC, but this way was easy to understand and worked perfectly at low cost.

Easy fix, job done, move on to the next problem.

JimB
 

audioguru

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I stopped using 74XX about 35 years ago and used CD40xx and 74HCxx Cmos logic ICs ever since.
I think some old teachers are still teaching about 74XX.
 

dr pepper

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Do you mean 74xx as in 7404, ie not 74ls or 74hc.
74nn have been obsolete for 25 to 30 years and are rare these days.
You can still get a range of 74hc and 74hct, it seems that only the more common ones are available these days such as inverters, counters and latches.
 

dr pepper

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I have 100 tube of those, and 74hc4094, 74hc4017, 74hc04's, and thats without looking, but I'm old and resistant to change.
 

audioguru

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74XX is old fashioned high input current TTL logic. 74HC and 74HCT are newer very low input current high speed Cmos which is completely different.
 

AnalogKid

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74xx chips, including all of the newer families, continue to be built and sold in the *billions* of units per year. The nice thing about a couple of logic chips vs. a PIC is that the logic gates do not need 6 months of firmware development, testing, and certification for a DO-160/DO-178 project. Same for space applications. Same for utility control systems. Same for patient-contact medical. Same for military. When *real* reliability is needed, the time to whip out a few dozen lines of code for a small task is only a few percent of the total effort.

ak
 

schmitt trigger

Well-Known Member
AnalogKid
Absolutely correct.

High reliability means the use of fully mature devices.
Also critical functions to be implemented in hardware, not software solutions.

Just last year, I designed a 3 phase motor controller where the overcurrent latch was implemented with some CD4093 schmitt-triggered NAND gates.

That could change in the future, though............
 

tomizett

Active Member
Off topic, I know, and a personal opinion but... As someone who repairs and maintains often undocumented electronics, I dread the day when all logic operations are relegated to the microcontroller. Hardware implementation is the ultimate in self-documentation; trying to troubleshoot a circuit containing a micro when you don't know what that micro is thinking is frustrating and usually fruitless. And of course if the mirco is dead, then the game is over - you can certainly replace it, but how was it programmed? No idea.
Don't get me wrong, I love microcontrollers and they have their place - it's just that I like to see them used for the things that they are uniquely good at and not just as a default solution.
 

atferrari

Well-Known Member
I presume the answer is yes but here it goes anyway: did actual TTL chips found their way in spacecrafts or their power consumption moved to other solutions?

I started learning digital techniques with them (Don Lancaster cookbook anyone?) until one day I decided to measure power consumption of a common 74??.

Still recall the day the technician in charge of maintenance and programming of an insanely expensive computer dedicated to process/display profiling data (oil industry), showed me the carefully wire wrapped boards full of TTL chips . I was fascinated.
 

RODALCO

Well-Known Member
Don Lancaster TTL Cookbook, I have that one too. Still have 3 or 4 power hungry TTL clocks running in my house 24/7. Extremely reliable for nearly 40 years and not missing a beat. All build with 74LS47, 74LS90, 74LS08 - 74LS00 and 74LS13 IC's. Written in older electrotech posts how to build them many years ago with schematics.
 

audioguru

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I got rid of my TTL Cookbook when I got my Cmos Cookbook in 1992.
 
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