I was sorting a bunch of my old stuff and found a bin of logic gates I used in my old engineering class in high school. IIRC it's stuff like AND, NOT, OR, NOR, XOR, NAND, etc. gates, along with a few 555s and some unidentifiable chips. I know the 555s still enjoy a cult following, but is there anything I can really "do" with these things anymore that would be actually useful and not something just like "turn on a series of lights if switches X and Y are on but Z isn't"? It'd be a shame to throw them out, but I'm not sure what use they still have.
>>1681348do logic nigga
>>1681348I once used a 555 to create a touch sensitive circuit to latch a relay. My old Ford rangers ignition tumbler was broken, and it allowed starting without a key. The circuit cut off the pilot wire to the solenoid until the the ignition was on and the antenna was "touched". This latched the relay and the car could start as normal. I hid the wiring and ran the antenna to a screw on the seat that was well isolated from ground. After a few years, that little circuit sold that truck.
>>1681348You can literally make a computer with logic gates. Just use your imagination and mess with them.
>>1681348I used plenty of 74 series logic gates in a computer I designed and built around the 65c816 CPU (derivative of the 6502 found in many popular old computers). I could've potentially used some CPLDs instead, but programming those can be difficult, along with finding them in hobbyist friendly packages.To make a long story short, logic chips are great for glue logic, although you'll provably end up with heavy enough gate delays that they'll only be useful in a slower system of only 1-20 MHz, and thats if they're HC, AHC, or similar. LS chips will only reach a couple MHz before they're tapped out.
>>1681444And you can do 10000x more with a modern $3 chip so why bother.
>>1681468I think you learn a lot by building an entire system, rather than buying a single chip to do the job. Don't get me wrong, my computer is not very powerful or capable compared to many things, but it did teach me quite a bit on the digital design front, and provided quite a few challenges along the way. Then I had to learn assembly to program it to do anything.I guess what I'm saying is, the point of the machine was not to compete with an arm SBC or microcontroller, the point was to build a computer from scratch.
>>1681468>he has never created things for the learning experience and personal amusementsad.
>>1681444You mention 74HC and the like topping out at 20MHz, but don't forget all the modern 74 series families like ALS, VHC, and AUC, which run in the 300MHz range and faster.>>1681468Depending on use case, a $3 microcontroller may not be fast enough.Like, you can run a AVR at 20MHz, but it won't be able to react to input as fast as discrete logic, since the AVR has to execute several instructions.Granted, most of the time when you need that kind of speed FPGAs are the modern solution, but for simple things like glue logic a 74 series chip will perform quite nicely.
>>1681348You can make a computer with these and even run a proper OS on it:http://www.homebrewcpu.com
>It'd be a shame to throw them out, but I'm not sure what use they still have.Give them to a student or list them in the classifieds for free. Everyone ends up happy.
>>1681905I know theres quite a few modern families, but in my experience most of those come in smd only, and a lot aren't 5v compatible, some don't even do 3v3, so I don't have much experience with them, since the parts I was working with were all 5vYou're right though i should've mentioned them.
>>1682975Off the top of my head, VHC and AS are 5v compatible.Your right that you can really only get them in surface mount packages though.I've kinda come to accept that passive components and legacy ICs popular in electronics courses are the only things still produced in through-hole packages, to be honest.