Can I use these ICs?

[MattAnonymous]

I got a few circuit boards from a junkyard and they have a bunch of socketed ICs.  Below is a list.  Can I use any of these?

SN7474n
SN74123n
DM7436/DM8095n
SN7402N
DM7415N
SN7404N
SN7400N
SN74116N
7451N 7849
SN74154N
SN74LS138N
5400DM
SN7451N

Thanks,
Matt

[ExpAnonColin]

Most 74__ series chips are digital-y, and pretty much useless to us, save flip flops and hex inverters and the like.

-Colin

[Brian Marshall]

you know someone told me the other day that when you salvage parts from boards, much of the time they are made overseas, and not subject to the same regulations that they are here.  many boards are coated with resins, glues, and sealers that release extreemly toxic chemicals when you put a heat gun on them..... just thought id warn you.

[Peter Snowberg]

Most 74xx and 74xxx chips are what's called TTL logic or Transistor to Transistor Logic. It was the big thing before NMOS was the big thing before CMOS was the big thing.

Almost all TTL chips are pure digital logic. They don't work in analog at all. One exception is the 74123 which can be used as an oscillator or a timer if you supply it with a regulated +5 volts.

The 5400 is a 7400 with military specifications.

The one 7400 series that is really useful for DIY stuff is the 74HCU04 which is like a 4049 and not a TTL chip at all. 4000 series CMOS is just a better way to go for most things unless you also need to deal with memory and microcontrollers.

Chips marked 74C or 74HC are CMOS and may be useful if you need logic functions. Check the datasheet for the part and see what you find.  

The SN in front says that they're from TI. That's a good place for datasheets.

Take care,
-Peter

[rankot]

The one 7400 series that is really useful for DIY stuff is the 74HCU04 which is like a 4049 and not a TTL chip at all. 4000 series CMOS is just a better way to go for most things unless you also need to deal with memory and microcontrollers.

May I use CD4069UBE instead of 74HCU04AP? I have a problem, 74HCU04AP are not arriving soon, and I want to finish my Echomachinex. Is it OK to substitute those two chips, pin layouts look the same, both are unbuffered CMOS inverters?

[anotherjim]

74HC ought to be faster than 4000 series. If the 74HC was chosen for its speed, the 4069 could give problems.

[rankot]

I don't think that the speed is so important in this case, it is simply two inverters in series and I suppose they are used as a oscillators (thus importance of unbuffered type). I wanted to be sure that this change can't harm the rest of a circuit, and to me it seems like a legit equivalent for this purpose, according to datasheets.



CD4069 has less I/O current capabilities, but those resistors limit currents to 1.5mA, which is not exceeding what datasheet says. But you're right, CD4069 is much slower regarding rise/fall times. So I will try to put it into the circuit and see what's going on.

[EBK]

I think the proper answer to the question, "Can I use these ICs?" is either "Yes," or "Yes, but we don't know how yet."