Anything I can use these ICs for?

[docz]

I just got a box of goodies from a friend who works as an electrician. They had cleaned out their storage rooms and binned a lot of electronic parts they didn't use anymore. My friend gave them to me instead of tossing them. I got a lot of good stuff, resistors, caps, connections etc. but I got a bunch of ICs I'm not quite sure what is used for. So far I've found two different types, SN74HC74N and MM74HC00N. From what I can find on google the first one is a dual NAND gate, and the second one is a dual flip-flop. What on earth are these things used for? And can I use them for amp/stompbox stuff? NAND is that like programming? (NOT AND) which basically returns false if both operators are true, but how can I use that in electronics? And what the heck is a flip-flop? I thought those were beach shoes!

DocZ

[PRR]

> What on earth are these things used for?

If you have to ask, forget it. There are 2,345 different logic chips, you are unlikely to ever run into a need for an 'HC74, and you can buy any gate-level logic chip for under a buck, often under a dime. Use them to shim wobbly tables.

BTW: you got your '74 and '00 reversed, I think.

NAND is really AND plus an invert (which is incidental to how early ones were made). NAND has a "fascinating" property: *ANY* logic machine can be built with only NAND gates. But most logic can be built more simply with an assortment of gate types, and you are a practical man, not a logician.

Flip-flop is a 1-bit memory. They come in a dozen internal connections. On yours, you hold the D pin at a high/low level until your CP pin (a system clock) rises. Now the flipflop remembers that level forever, or until the next clock, or until you tickly the set/reset pins.

The 'flop which might be useful "here" is the toggle flop. Blip it, it goes one way, blip again, it goes the other way. Connect the outputs to relays or FETs, you can switch between two states (such as bypass or effect). However a T-flop is so simple you often wire it from a couple NAND or NOR gates. And in effects, you don't need the high speed of HC logic, but you often want the low power and high voltage of CMOS logic.

So your friend had the right idea. Put the ICs on eBay for $5 and you probably won't get any takers; they are hardly worth shipping.

[docz]

Ok, just so we are clear, I'm actually a logician trying to be practical

The reason I ask is that is how I have learned everything I know. By asking people who knows more about stuff than I do.

So if I got this correctly, the NAND is a logical component, meaning it can be used like a NAND boolean operator just this is done by power?

if A has power and B does not, output will be on,
if B has power and A does not, output will be on,
if neither A or B has power, output will be on,
if both A and B has power, output will be off

correct?

And the flip flop is a one bit memory, and can be used as a switch combined with a toggle?

hit toggle once, flip flop is 1
hit toggle again, flip flop is 0?

DocZ

[jammybstard]

Correct!
That takes me back, my first job was working for a company that repaired obsolete industrial controls, it was nearly all 7400/4000 series TTL/CMOS logic; I had to sit at a desk with a big sheet of A3 paper and a stack of texas instruments data books and draw out the logic circuits, which we would either repair or replace with a microprocessor clone! I havent seen any for a while, the cheap tweakable microprocessor killed it all off really, shame really, hard wired logic was much more elegant.


http://en.wikipedia.org/wiki/7400_series
http://en.wikipedia.org/wiki/NAND_gate

[docz]

Great!

Ok, so how could this be used in a stompbox?

Could I use that NAND to hook up two guitars to an amp, with two switches? Making sure only one guitar is hooked up at a time?
Could I use that Flip-Flop for instance as a switch for a mid scoop pushbutton on amp for instance?

Or don't these things fall into the working conditions of the IC's?

DocZ

[Seljer]

you can use the flipflop to debounce a switch in a situation where that might cause problems, or use it to use a momentary switch two toggle between two states

or the octave down effect in the mxr blue box is achieved with a flip flop

[Top Top]

Octave down, also can be used for some synth-like circuits. Google "lunetta."

But don't the 74x chips run on 5v? Not necessarily a problem, but probably need their own supply.

[PRR]

> By asking people who knows more about stuff than I do.

Some of them already wrote it down. That's really a better use of their time than one-by-one questions. jammy gave you two links. Google will find more. A trip to a *good* used-book shop will probably turn up a bunch of texts and databooks, hours of reading.

> how could this be used in a stompbox?

Logic chips are tools to a task. Like a shovel or hammer. The number of ways they can be used is infinite. Yes, it will take a little leap of insight to see what is possible, and what is useful.

But an observation: You have a box of "tools". I have a box with shovel, hammer, saw. Do I look in and wonder "What can I dig with a shovel?" Ah, no. What happens is I find some dirt where I want a hole (fence, garden, etc), and I wonder what tool I should use, and if I already have it or will have to spend money for one.

You could invent a use for these chips. But at this stage of learning, you will probably use someone else's plan. And they will specify the "tool", logic-chip, they used. And as TT says, 5V chips are awkward in a 9V world, especially when the 9V CMOS chips will do the job, often better.

Or, build a 5V breadboard, pushbuttons, LEDs with resistors, and learn yourself basic digital. Nothing beats actually DOING it. (And a pre-made flip-flop may be easier than my first f-f cobbled together with very expensive discrete transistors.)

[Taylor]

> By asking people who knows more about stuff than I do.

Some of them already wrote it down. That's really a better use of their time than one-by-one questions. jammy gave you two links. Google will find more. A trip to a *good* used-book shop will probably turn up a bunch of texts and databooks, hours of reading.

> how could this be used in a stompbox?

Logic chips are tools to a task. Like a shovel or hammer. The number of ways they can be used is infinite. Yes, it will take a little leap of insight to see what is possible, and what is useful.

But an observation: You have a box of "tools". I have a box with shovel, hammer, saw. Do I look in and wonder "What can I dig with a shovel?" Ah, no. What happens is I find some dirt where I want a hole (fence, garden, etc), and I wonder what tool I should use, and if I already have it or will have to spend money for one.

You could invent a use for these chips. But at this stage of learning, you will probably use someone else's plan. And they will specify the "tool", logic-chip, they used. And as TT says, 5V chips are awkward in a 9V world, especially when the 9V CMOS chips will do the job, often better.

Or, build a 5V breadboard, pushbuttons, LEDs with resistors, and learn yourself basic digital. Nothing beats actually DOING it. (And a pre-made flip-flop may be easier than my first f-f cobbled together with very expensive discrete transistors.)

I like this guy.

[oldschoolanalog]

I like this guy.

+1

[Joe Hart]

I like this guy.

+1

Definitely. And I love his little picture -- I can't decide if he's a wacky psychiatrist, an evil scientist, or Satan. But he always has very intelligent and insightful (and often hilarious) information to share. I would love to buy him a drink.
-Joe Hart

[docz]

Thank you for your replies, when it comes to books, me and books have never been good friends. I'm just not a good reader, never have, and probably never will. I read slow, the words get mixed up and jumbled, and I have to go back and read over and over again. Finally I get a nasty headache and the day is ruined. Talking to people and trying stuff out - works much better for me. It is amazing how much stuff you can learn just by doing it and asking questions along the way. I write computer programs for a living, in a lot of different enviroments. I have never read one single book on software development, but I have taught myself the skills I needed to make a successful living of it for the past 15 years. I remember when I first started out, I couldn't understand much of it. But after learning some basics from friends, my brain started shifting into another gear and started thinking about how I could use what I had learned into making things happen.

DocZ