[RotorRouter]

I take a 7406 Inverter chip (SL74LS06), no resistors and a 5VDC power source.

With the chips Vcc connected to 5VDC and the GND connected to GND, why does 5VDC on an input pin not give a LOW voltage on the corresponding output pin and why does 0VDC on an input pin not give a HIGH voltage on the corresponding output pin?

Should I be concerned about amperage or using pull-up or pull-down resistors?

Help & thanks.

[Al_The_Man]

7406 I believe is an open collector, so you need a pull up resistor or a load of some kind in order to register an output.
I just checked it is an inverter with open collector,30vdc max on the output.
Al.

[gar]

060517-1846 EST USA

RotorRouter:

Questions like this you should try to answer yourself by finding the datasheet and studying the information contained therein.

I like to go direct to National Semiconductor, www.national.com , but they do not list the 7406 anymore. Probably stopped manufacturing it years ago. Then I went to www.mouser.com and searched for SN74LS06N. A TI data sheet is available here.

Rather than ask limited specific questions you need to study the broad range of components you want to work with, logic circuits, electrical circuits, and so on. Libraries or your own books are the best way to do this. When your own study brings you to a point that you can not understand, then ask others questions.

.

[JRoque]

I, on the other hand, think all questions are fair. Very often I find myself lost in a sea of datasheet information that can be confusing, especially for new parts or technologies. The first thing I look for in a datasheet is a "typical application" which is likely to answer the bulk of my initial questions.

Al has the correct answer, as usual.

JR

[RotorRouter]

Thanks guys.

Gar. Your points are valid. I had the spec sheet and had spent 5-hrs searching for the answer. Frustration was setting in. Therefore a 3-minute post to those 'in the know' seemed to offer the fastest relief. And it did. Thanks again.

Dave

[ViperTX]

Well....as Gar mentioned.....Open Collector means you got to tie it to some pull-up resistor network....if the output is a TTL output then you don't need the pullups or pulldowns.....

[NC Cams]

Yes Al had the answer but how did he learn it??? Bet it was knowledge gained from studying a spec book/manual before there was an internet message board to go to.

An old college prof once told me that he'd give nearly full credit on a test if you could tell HOW and WHERE to find the answer as opposed to just writing in the number. Why? It was more important to KNOW where and how to find the answer that to merely spit it out.

Sadly, we've gotten into the "look it up on the net" mode of thinking. Prior to M/B's, one had to try to score spec manuals by calling sales offices and simply asking for them. I still have books on 7400 series and other obsolete chips that I refer to all the time.

Why? Faster and easier to look up in the book than to log on to the net and search. Sadly, the days of calling National and others for a spec manual ar gone - they don't publish them anymore - bo hoo.

However, they now "stock" PDF's which can be downloaded quite readily and take up MUCH less space than the old manuals. Woo-hoo

Enter Google. Speaking of which, you'll be amazed to see what a "7406" search on Google turns up.... One especially productive link led to this site:

http://focus.ti.com/docs/prod/folder...plicationnotes

wherein some application notes can be found here:

http://focus.ti.com/logic/docs/logic...emplateId=5985

Regarding techno-babble spec sheets that make no sense unless you're a electron geek, maybe this will help:

http://focus.ti.com/lit/an/szza036b/szza036b.pdf

God bless Google...

NOTE: the reason why some application notes may NOT be listed for the 7406 (an obsolete part that you'd be lucky to find anymore - thankfully TI still makes them) is that it is an open collector output.

Since open collectors are a fundamental "building block" circuit in electronics, I suspect that the chip makers think it is too mundane of an application to show someone how to use because it is so elementary in nature.

Sadly, basic books aren't that easy to find anymore - the ones I learned from and got from Radio Shack aren't in print anymore - been replaced by cell phone and walk man section.

Anywayl, sort of, "seen one open collector, seen them all" situation. All you have to worry about is too much voltage and too much curent and the externally selected pull-up resistor that is to be chosen by the user to interface the O/C with the outside world controls that.

[Al_The_Man]

Yes Al had the answer but how did he learn it??? Bet it was knowledge gained from studying a spec book/manual before there was an internet message board to go to.
.

Well, yes, and graduation from City & Guilds of London (UK) in Electronics, Which helped, followed by School of Hard Knocks
I can see why to the uninitiated that spec sheets may seem a bit cryptic, because if there is no example shown, the implications of the Words 'Open Collector' may not sink in.
BTW, while on the subject if you are looking for this type of IC to interface to the outside world, there are inverter drivers that are better equipped like the DS2003 (there are others) these are darlington (another word to look up), TTL input, open collector 350ma 50v with built in free-wheel diodes for suppression.
I am not sure it is 'sad' to have the Internet for reference, It sure makes my job easier with the wealth of information available.
Al.

[NC Cams]

Internet is "sad" because it can be FAR too easy to ask and you'll get somebody who'll save you the time of doing the research and giving you the answer instead of learning on your own (guilty as charged).

Not sad because it can be SO much easier to find stuff IF YOU KNOW HOW TO LOOK as it what I came up with in post #7 via google.

GAR is right, I was simply too busy showing off and showing how in same post....

[fkaCarel]

I once read an article about reprogrammable logic. The space savings compared to discrete chips is enormous. So I started. It was an humiliating experience. All the logic in the world is based on And, Or, Exor, Not and a register. This means that if you have a container of (now taking the book, which can't be bought anymore), 74LS08, 74LS32, 74LS86, 74LS04 and 74LS74 you can make an although slowish Pentium or whatever. The advantage of reprogrammable logic is great, I can start a Pcb earlier, design the logic and change it without any fysical changes. The assortment of chips is intimidating. But you have to learn to specify: I need a 4 input And chip with an inverting output or a cascadable counter. With your own specification you can hunt the chips easily down.

Carel

[Al_The_Man]

I assume you are refering to PAL programing, I would imagine PIC's have replaced these to a great extent, No?
Al.

[RotorRouter]

Not only did Al provided the answer in his first post he also realized the problem in his second. I, stupidly, did not think that the expression 'open collector' was significant and therefore when looking in all the wrong directions.

In school, the books provide most of the information, however the teacher's input sure helped keep the motivation up and this transfer of information from stalling.

IMHO

[NC Cams]

Electronics if full of non-sequitors.

For example, you apply current to the base of an NPN transistor to turn it on - as in make it conduct (makes sense) but you apply current to the base of a PNP to turn it OFF which simply doesn't.

It would seem that if you want to turn something on, you simply switch power on and vice versa to turn it off - that's how water faucets work and they tend to use water pressure and volume as analogies for voltage and current - which does and doesn't pertain to electronics - go figure.

However, you use a pull-up to keep the device on and then apply power to the base of an NPN OC transistor connected to the pulled up pin to turn it "off". Sort of oxymoronic to a mechanically inclined person to apply power to turn something off. Sort of like fighting for peace....

I, too, used to ask an EE for the info on a lot of circuitry. However, he soon tired of answering mundane questions and stopped making time for me which forced me to learn the illogic logic and operation of many electronic devices. I can handle minor and, or logics but could never do a complex circuit involving PLC's or a daisy chain of logic IC's.

How did I learn??? Bought books, got component catalogs, got into model train ciruits, makde lights flash and trains move and then bought some 1970's CNC lathes that worked - until we moved them.

At that point, they stopped working altogether and desperation set in. I had to figure them out myself - as in comlete interconnect rewire and troubleshoot of undocumeneted grounds and fried Fanuc M/B's due to improperly grounded BTR's. Didn't know about this site until way, way after the Fanuc fiasco was dealt with...

You'd be amazed at how FAST you learn electronics when you have 3 formerly functional 30 year old, like new, CNC "junk" that you need to get back up and running to make the rent payments.

Using M/B's to "help" you out is one thing. However basic learning of electronic fundamentals is something that is really a necessary and often self taught/learned skill when it comes to DIY CNC. If a person is "avoiding" the learning of basic electronics and computers when it comes to DIY CNC, big mistake. Unfortunately, it (electronics) is not always easy to learn in a self taught environment. You still have to try and some of the electronics hobby magazines can be a great help. Reason; they show circuits and exlplain how/why they work. Once you get the basics, it can be real easy to figure stuff out after that

This is what GAR surely was illuding to. My "contribution" to the cause is/was nothing more than to show that a simple bit of "google" researching can lead to a wealth of knowledge if you look deeper past the first page or two....


I know that there were some people who were not unhappy to see me have problems with my archaic CNC's that didn't run. The satisfaction of getting them back up and running along with the "how the hill did he do that, he's not an electrical engineer???" was the priceless part that still has some folks amazed...

BTW if you think electronics is difficult, you ought to try to research how to do cam designs. Lots of theory, little practical knowledge presented for the neophyte and, definitely, no M/B's where questions can be asked and answered....

[lwill]

Sadly, basic books aren't that easy to find anymore - the ones I learned from and got from Radio Shack aren't in print anymore - been replaced by cell phone and walk man section.

http://www.amazon.com/gp/product/187...lance&n=283155

This book use to be sold at Radio Hack, Is that one you are reffering? It is back in print, as well as other Forrest Mims, III books. He wrote all of the RS books. There are some others on his sight:
http://www.forrestmims.com/
I learned enough practical knowledge from his books (and others) to let me coast half way through DeVry (BS-EET) till I hit Laplace Transforms!
If you want to learn on your own, definately get his books! I lost my copy of hs Engineer's Notebook and was amaized to find a new copy a few years ago at Barns and Noble. Sadly (as he states in the preface) alot of the basic building block chip in the book are no longer available, but very good referance.
By the way, I found Mims sight using Google!

[NC Cams]

The Mims books are definitely "MUST READS" for the neophyte DIY CNC'er, especially those who are electronically challenged.

I'll add the Mims links to my reference "cheat sheet". You can bet that I"ll be posting it as an answer sources for future basic electronic questions that may be posed.

I still contend that it is better to teach a hungry person (how to) fish as opposed to offering them some of yours. If you teach them to fish, they'll have the where with all to never go hungry again.

Do it the other way, they'll merely be back later asking for more free fish the next time they get hungry.....

By the way, I learned a LOT from professors who answered questions by ASKING me more in return (insted of simply giving the answer). This tact forced me to think out/thru the problem better in return.

[fkaCarel]

To Al:

No, these are Lattice chips (60mhz, 2000 gates, 96 registers). I use them as "glue" logic for my computers. It is also possible to make complex bus-driven chips with it. For example: a 60Mhz 32 bit AB counter with "latch at first read" for sequential reads fits in easily. The bus capabilities and instant responce makes them in certain cases superior over microcontrollers, they are all bottlenecked in communication and their logic is serial. The decision factor between the two is in the time domain.

Carel

[Al_The_Man]

Electronics if full of non-sequitors.

For example, you apply current to the base of an NPN transistor to turn it on - as in make it conduct (makes sense) but you apply current to the base of a PNP to turn it OFF which simply doesn't.

...

No non-sequitor there I'm afraid.
Apply base current to either PNP or NPN they will both turn on.
Although voltage dividers are often used to bias bi-polar transistors, they remain Current operated devices.
Al.

[Al_The_Man]

To Al:

No, these are Lattice chips (60mhz, 2000 gates, 96 registers). The decision factor between the two is in the time domain.

Carel

Carel, I think this is what I meant to imply by PAL (programmable array Logic)?
Which obviously operate in closer to real time than the embedded processor type of array.
Al.

[fkaCarel]

PAL (and GAL) were names used for the small devices, like 22V10. Lattice calls this IspLsi, In system programmable large scale integration. This has all evolved to FPGA, flexible programmable gate array's, see Xilinx. Way beyond my budget and needs.

Carel

[NC Cams]

Al:

if you apply base current to a NPN, it conducts current thru the collector to emittor.

if you apply base current to a PNP, it STOPS conducting current thru the "I can't keep them straight" conducting elements.

Turn it on to make it stop might not be a non-sequitor but it surely MUST be an oxymoron.

That concept is still something I have trouble coming to grips with - apply current to make it stop?!?! Do something, anything JUST MAKE IT STOP!!!!

It is frankly, easier to figure out if the refrigerator light goes out when/if you close the door.... Something I've come to grips with.

At some point, some of us simply HAVE to take the position that since you can't see electrons, you can't trust them.....