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12 LED resistance circuit help

A

Anthony Fremont

Jan 1, 1970
0
What a hoot. Lord Garth brought the other thread up, not me. I didn't
know that was not allowed anyhow. Is this another of your personal
rules of engagement?
work.

What, no smart comments proving me wrong?

I think (outside of this thread) that most of the posts I've made here
contained some kind of useful information pertaining to the thread.
Perhaps you could point us to some of my "empty" posts? Would you like
for me to do the same for you?

Nothing to criticize again? I must be losing my edge.
 
J

John Fields

Jan 1, 1970
0
Only so far as what he posted. I thought he made his skill level fairly
clear.


That's completely beside the point.

---
No it's not. The point was that a 0.6mA was a typo and the relay
would have clicked in whether that typo was there or not. Or do you
think there's some sort of entanglement between a typo and a physical
circuit which will keep it from working?
---
Just like the fact that it wouldn't have worked anyway.

---
You say that now like you knew it then, but the _fact_ is had Fred not
found it you'd still be just as in the dark now as you were then.
---
And you think that is something to brag about?

---
If you think that's bragging, then I think you need a course in
remedial English comprehension. It's a flame, boy. The clue should
have been the "your whining" part.
---
LMAO I'm not the one
touting myself as a "professional circuit designer".

---
No doubt because if you tried it you'd be laughed off the planet.
---
I'm in it for the hobby and I've never pretended any different.

---
Good move on your part since the pretense would easily be found out.
---
Perhaps you should have
told the OP that your circuit was untested and unsimulated, because even
I made the mistake of figuring that you actually posted stuff that you
knew would work.

---
"Even" you? My, my, you _are_ a pretentious little prick, arent you?

Most of us who have been around these technical newsgroups for any
length of time realize that unless it's explicitly stated that the
circuit has been tested or simulated, it hasn't. I see you have yet
to learn that. For the most part, most of the stuff we post is off
the top of our heads and is usually either right on or pretty close to
it, because it's stuff we do every day to make a living. However we
_do_ make errors from time to time, and some sharp individual will
usually catch the error and provide feedback. Luckily, Fred Bloggs
was there to catch mine and to graciously provide a solution.

You, on the other hand, seem to be interested in little more than
assuaging the effects that "current hogging" incident had your ego.
---
I will certainly view your schematics from the proper perspective
from now on.

---
Yes, you should. Consider them documents from which you can learn how
to catch mistakes. However, I suspect that you'll miss even the most
glaring of technical errors and report back, scathingly, on all the
typos you find, LOL!
---

First off the sheez part wasn't addressed to you. You might have
deduced that from the punctuation.

---
Well, duhhh...

If you can't write properly, how can you expect people not to
misunderstand you?
---
Secondly I was being sarcastic, you
should have been able to tell that from the entire context of my post.

---
So, when you can't defend yourself technically you slip into sarcasm?
---
At any rate, you are the one setting the precident around here of
jumping down someones throat when you don't like the accuracy of their
posts.

---
If you want to find out how really stupid that statement is I suggest
you go to Google groups and read through my last 10,000 posts then,
once you're done, report back here with what you've learned.
---
Or did you already forget about the photocell and resistor
fiasco in your unending love/hate relationship with Larry?

---
I'd hardly call that a fiasco; more like a disagreement, and it
started like this:

"
R1 = 6.2k
R2 = 400 -> 15M
R3 = 620



R1 (R2 + R3)
Rt = --------------
R1 + R2 + R3



6200 (400 + 620)
Rt1 = ------------------ = 875.9 ohms
6200 + 400 + 620



6200 (15e6 + 620)
Rt2 = ------------------- = 6197.4 ohms
6200 + 15e6 + 620


875.9 ohms to 6197.4 ohms isn't 1k to 5k.
"


BTW, I don't think my comment was all that bad, certainly not an FU or
anything like that. I noticed that Mike pointed out your error and
you didn't respond. I thought you might like to know about it. :)

---
Bullshit. You figured that since I called you on that
"curent-hogging" stupidity you'd try to throw a little barb to get
even.
---
It certainly woke you up didn't it. :-D

---
I stay awake.
---
At any rate, the sole reason that I even mentioned you was because you
had already made your attempt at setting me up. Given your typical
behavior lately, I knew what was coming next. I figured my way of
pointing out your mistake was just beating you to the punch. Obviously
I was correct, since you are now so pissed over it.

---
I have no idea what you're talking about.
---
I certainly didn't cuss you out over it though.

---
That's because you had nothing to do any "cussing out" about and
because you're a pussy.
---
Where did I lie?

---
You said: "I didn't feel the need to jump in and make a scene though."

After you said: "Hey Fields, are you ever going to acknowledge/correct
your mistake in S.E.D about max collector current on the 2N4401?
sheez...."

If you can't see that as making a scene, then saying that you didn't
feel the need to, then you're even stupider than I thought.
---
That was his choice. Like you, I reserve the right to respond when and
how I want.

---
So, you admit your reply was confrontational, and yet you said that
you didn't feel a need to make a scene. You just can't keep your
facts straight, can you?
---

---
And, in view of the fact that you've proven yourself to be a liar, and
a stupid one at that, I maintain that you actually meant 'current
hogging' and decided that 'power hogging' would be a nice little
phrase to switch to to get you out of a jam.
---
..
..
..
No need to sue, you are doing enough damage to your business and
reputation all by yourself.

---
Yup, I thought so. You're the stereotypical petulant little puke who,
when she starts running out of ammunition starts whining about how I
should run _my_ business and how I should run _my_ life.
---
You accused me of weaving and bobbing, so I figured that I hadn't been
plain enough for you.

---
You were plain enough, the bobbing and weaving part was about the
transfer to the "power hogging" ploy, the intent of which was to make
it seem like you knew what you were talking about, but merely used the
wrong choice of words to describe what you meant. What I'm saying is
that I think you were being intellectually dishonest in that there is
no use of "power hogging" in the context into which you cast it.
"Power hogging, in all the cases I've been able to find refers to one
device, alone or in parallel with others connected to a common power
supply, which draws what seems to be an inordinate amount of power
from the supply.
---
Then, why did my comment upset you? I was only prompting you to fix
your error. I didn't call you any names, or use an cuss words so why
did you find it so upsetting?

---
Again, the context of your "prompt" was goading and your attitude was
clearly confrontational, yielding a richly deserved insulting reply.
---
I think I can still tell the difference between current, power and
energy.

---
Really? Then be my guest and tell us all about it...
---
I think you know that too or you'd be filling your posts with
links to all my past errors.

---
I can't imagine what makes you think you're important enough that I
should give a shit about your past errors.

I know nothing about you which precedes your "current hogging" faux
pas, and I'm _certainly_ not interested in the genealogy of the huge
family of errors I'm sure you've procreated over the years.
---
Not half as weak as someone that feels a need to dominate a basics
newsgroup just cuz they're an expert in the field.

---
Awww... poor baby's playing the passive-aggressive "If you're smarter
than me then why pick on me?" card.

I don't feel a need to dominate the NG, sweetie, but what I do like to
do is bring down self-important little bullshit artists like you, just
for fun. And as far as being an expert goes, I could be a complete
moron and you'd still have to consider me an expert.

BTW, what happened with running those numbers to see whether the power
dissipation spec of an LED with Vf max in series with an LED with Vf
min and If running through _both_ of them would be exceeded?
---
..
..
..
Perhaps if you acted a little more civil around here, I would be
inclined to be nicer to you. As it stands, you certainly are
demonstrating that you deserve far less courtesy than I've shown you.

---
If you'd pull that narcissistic little head out of your ass you might
come to the realization that you're not the arbiter of who's deserving
of what, and you might find that I am, in fact, civil. That doesn't
mean that when a disingenuous little twat like you wanders in here and
starts playing games that she's not going to be called on it.
 
A

Anthony Fremont

Jan 1, 1970
0
John Fields said:
---
No it's not. The point was that a 0.6mA was a typo and the relay
would have clicked in whether that typo was there or not. Or do you
think there's some sort of entanglement between a typo and a physical
circuit which will keep it from working?

The point had nothing to do with whether it worked or not. The point
was your mistake, or "trypo" as you like to call them.

I never bothered to look that close. Obviously Fred is well aware that
you often post non-working circuits.

It might be different if I was actually looking for errors in the
schematic, but I simply wasn't. I just noticed the glaring "trypo" in
the text.

Do you think that I have no other skills, or is circuit design all that
is important?

Kinda like the pretense where you come off as a civil human being?

Actually, I meant that in a gullable sort of way. I've got your number
now though.
Most of us who have been around these technical newsgroups for any
length of time realize that unless it's explicitly stated that the
circuit has been tested or simulated, it hasn't. I see you have yet
to learn that. For the most part, most of the stuff we post is off
the top of our heads and is usually either right on or pretty close to
it, because it's stuff we do every day to make a living. However we
_do_ make errors from time to time, and some sharp individual will
usually catch the error and provide feedback. Luckily, Fred Bloggs
was there to catch mine and to graciously provide a solution.

You, on the other hand, seem to be interested in little more than
assuaging the effects that "current hogging" incident had your ego.

Actually, I've been getting a kick out of watching you blow your top.
:)
---


---
Yes, you should. Consider them documents from which you can learn how
to catch mistakes. However, I suspect that you'll miss even the most
glaring of technical errors and report back, scathingly, on all the
typos you find, LOL!

I seriously doubt that I'll be reporting back much of anything about any
of your circuits. I do suspect that I will be hearing from you more
often in the future though.
---



---
Well, duhhh...

If you can't write properly, how can you expect people not to
misunderstand you?

My comments in the original post were rhetorical, haven't you figured
that out yet?

What's to defend, I admitted my little faux pa.

I didn't have to read 10,000 of them to figure out that you often go off
like this. Four letter words, invectives and ad-hominem attacks seem to
be a part of your regular forte.
---


---
I'd hardly call that a fiasco; more like a disagreement, and it
started like this:

"
R1 = 6.2k
R2 = 400 -> 15M
R3 = 620



R1 (R2 + R3)
Rt = --------------
R1 + R2 + R3



6200 (400 + 620)
Rt1 = ------------------ = 875.9 ohms
6200 + 400 + 620



6200 (15e6 + 620)
Rt2 = ------------------- = 6197.4 ohms
6200 + 15e6 + 620


875.9 ohms to 6197.4 ohms isn't 1k to 5k.
"


BTW, I don't think my comment was all that bad, certainly not an FU or
anything like that. I noticed that Mike pointed out your error and
you didn't respond. I thought you might like to know about it. :)

---
Bullshit. You figured that since I called you on that
"curent-hogging" stupidity you'd try to throw a little barb to get
even.

Really? Do ya think so?
---


---
You said: "I didn't feel the need to jump in and make a scene though."

After you said: "Hey Fields, are you ever going to acknowledge/correct
your mistake in S.E.D about max collector current on the 2N4401?
sheez...."

If you can't see that as making a scene, then saying that you didn't
feel the need to, then you're even stupider than I thought.

As I said before, I didn't see a need to make a scene when I first saw
your mistake in SED. After that, when you posted your little trick
setup question in SEB, I felt a bit different. And then after Watson's
snide little remark about attrocious advice, I posted my little
sarcastic rant. And now here we are. Is that timeline really so hard
to grasp?

See above.
---
And, in view of the fact that you've proven yourself to be a liar, and
a stupid one at that, I maintain that you actually meant 'current
hogging' and decided that 'power hogging' would be a nice little
phrase to switch to to get you out of a jam.

As I originally posted in reply to your little trick query:

<quote>
Perhaps "dissipate more power" would have been more appropriate than
"hog more current".
</quote>

So as we can all plainly see, 'current hogging' is your own little
fabrication of terminology that I never used.

If you think I'm running low on ammo, just keep posting. ;-) I could
care less how you run your business _or_ your life. That is until you
wish to horn into my life with your petulent, pedantic crap.
---


---
You were plain enough, the bobbing and weaving part was about the
transfer to the "power hogging" ploy, the intent of which was to make
it seem like you knew what you were talking about, but merely used the
wrong choice of words to describe what you meant. What I'm saying is

Do you think that you've somehow proved that I didn't know the
difference?
that I think you were being intellectually dishonest in that there is
no use of "power hogging" in the context into which you cast it.
"Power hogging, in all the cases I've been able to find refers to one
device, alone or in parallel with others connected to a common power
supply, which draws what seems to be an inordinate amount of power
from the supply.

Again, like as stated earlier. I was originally going to say "juice"
not current and not power. Again, I wish that I had just so I could see
how you could have twisted that around. Is juice power, or is it
current or maybe even energy? Again, my original intent was not to use
the word power either, even though it would have been the "most correct"
term. Hard to believe that set you onto a personal crusade to prove me
a liar.

What type of reply do you think you deserve at this point in our
relationship?

Why do I think that no matter what I posted you would ridicule it?

As you have so aptly demonstrated, you would leave no stone unturned in
order to crucify me.
I know nothing about you which precedes your "current hogging" faux
pas, and I'm _certainly_ not interested in the genealogy of the huge
family of errors I'm sure you've procreated over the years.

Too funny.

I never said that I thought you were smarter than me. Only that you
knew more about electronics. Don't flatter yourself, there is a
difference.
I don't feel a need to dominate the NG, sweetie, but what I do like to
do is bring down self-important little bullshit artists like you, just

Self important bullshit artist? That's got to be the most serious case
of projection I've ever seen. Do you see me waving my credentials
around? Do I have a sig line making bodacious claims?
for fun. And as far as being an expert goes, I could be a complete
moron and you'd still have to consider me an expert.

That's not far from how I see things right now.
BTW, what happened with running those numbers to see whether the power
dissipation spec of an LED with Vf max in series with an LED with Vf
min and If running through _both_ of them would be exceeded?

I don't know, what happened? How about you pick your own experiments,
and I'll pick mine.
---
.
.
.


If you'd pull that narcissistic little head out of your ass you might
come to the realization that you're not the arbiter of who's deserving
of what, and you might find that I am, in fact, civil. That doesn't

Really, and I'm supposed to be convinced by that statement? ROTFL I
think I'll continue to decide for myself who I respect.
mean that when a disingenuous little twat like you wanders in here and
starts playing games that she's not going to be called on it.

Yeah, you're real civil.
 
J

John Fields

Jan 1, 1970
0
However you wish to see it John, though I didn't use any cuss words.

---
'Crap" is a cuss word, and besides, "The thought is the same as the
deed."
---

I'd go with jumpers on a micro. They're cheap and highly configurable.

---
Not as configurable as a delta R, and good luch with those jumpers on
an 8 pin chip.
---
An SSR doesn't qualify as a relay?

---
Not as a relay with mechanical contacts, but it doesn't matter. The OP
asked for something which could _drive_ a relay, which is what I gave
him. I showed a mechanical relay because that's what he said he was
going to use, but if he wanted to switch to an SSR, that would be up
to him.
---

The same goes for test equipment, soldering stuff etc.... It's just one
more tool that you need, nothing more. A good PIC programmer is less
than $100. Compared to the $150 I spent on my audio frequency generator
that I almost never use, it's a great investment.


But it would be worth buying a DMM, a soldering iron, solder, etching
stuff etc.....?

---
You'd need that stuff whichever way you decided to go, but you'd only
need the other stuff if you were going to implement the device using a
micro, so it would be stupid to go that way when the other way is so
simple.
---
Well, I guess that I see PIC chips like you see 74xx's

---
I doubt it. I work in both camps as well as in analog, and so far
you've demonstrated no skill with anything other than some alluded-to
ability to substitute programming for hardware you admittedly don't
understand and don't want to "take a lifetime to learn", or something
like that.
---
Burning yet another straw man, you really are a fire bug. I don't
recall asking anyone to spend money on equipement to be used once.

---
It's not a straw man at all.
When you insist that using a µC is a better solution than using
"discrete" logic, then if that insistance bears fruit, the requirement
for the equipment necessary to implement your solution will become
de rigueur. If the breadth of the project is the yield of a single
unit with a cost basically down in the noise compared to the required
expenditure in time and money to complete the project, then doesn't it
seem stupid to you to do it that way when doing it in hardware would
be so much faster and less expensive?
---
As I "self agrandised" before, if I was adamently suggesting a PIC to
someone, I'd be offering some help to go with it. You can make of that
what you wish.

---
From what you've offered so far, I would suggest that anyone who
decides to go that route find help elsewhere.
---
Er um, because I don't want to. You really ought to stop trying to
control things around here. Ordering people around on usenet is not
likely to win you many friends.

---
Er um, because you're a chickenshit and you know that if you do you're
going to wind up getting your ass handed to you. Again.
You really ought to follow your own advice, hypocrite. You telling me
to stop trying to control things around here is you trying to control
me. Friends I've got. Insignificant gadflies like you I don't need.
---
Programmers and dev tools don't count. We've already covered this.
They are in the same category as all other dev tools and electronics
equipment you own.

---
Other than your just being obstinate, I fail to see why, (without
even going into the learning curve part of it) you think that paying
money for dev tools which will only be used once is better than not
having to pay for the dev tools, yet winding up with exactly what you
want anyway.
---

It's certainly not half as expensive when you factor in a board and the
rest of the common parts. The difference quickly shrinks to ~10% or
less, now doesn't it?

---
That's a good point but, bottom line, you still save about 50 cents if
you don't do it with a micro and you don't have to learn how to do it
and buy all the stuff to do it with if you're not going to do it
again.
---
Admittedly for one off, it's pretty hard to be cheaper using an 8-bit
micro. A 4-bit proc would do the job, and it would be cheaper. BTW,
your quoted prices were a bit low as shown on Digikey, so things aren't
as bad as you wish to make it seem. Of course your price was 70 cents
yesterday and now it's only 63 cents, so why am I not surprised?

---
Because you're stupid?
---
According to Digikey, the fairchild 4060 is 77 cents in single qty, the
ST part is 55 cents each.


What about the electronics learing curve? It's only about 1000 times
larger, be for real. That's the same old tired mantra formerly sung by
"professional tube circuit designers" when whining about having to learn
yucky old transistor theory.

---
Dumbass, the OP over on SED wasn't interested in spending a great deal
of time and some bucks on learning how to design a µC timer; what he
wanted was something quick and easy which he could solder up, probably
on a piece of perfboard, which would do what he wanted. That's what
he got, and I got private email from him thanking me for the circuit
and letting me know that he'd let me know how it worked out. Rest
assured that I'll post the good news when I hear it.

Now, do you have any comments on whether it'll work or not? Why don't
you build one and find out? It'll only cost you five bucks or so and
we'll learn whether you know how to solder or not. Or wire-wrap. Or
whether you're just plain ol' fulla shit.
 
A

Anthony Fremont

Jan 1, 1970
0
Crap is just a tad less ugly than FU, don't you think?
configurable.

8 pins makes it trickier with just 6 for i/o, but not impossible. 1 pin
to drive the relay leaves 5 jumpers and that still gives me an easy 32
steps to be used however I wish.
---
Not as a relay with mechanical contacts, but it doesn't matter. The OP
asked for something which could _drive_ a relay, which is what I gave
him. I showed a mechanical relay because that's what he said he was
going to use, but if he wanted to switch to an SSR, that would be up
to him.
---



---
You'd need that stuff whichever way you decided to go, but you'd only
need the other stuff if you were going to implement the device using a
micro, so it would be stupid to go that way when the other way is so
simple.

For a one off, one-time project either way would be stupid from a cost
vs. return viewpoint.
---
I doubt it. I work in both camps as well as in analog, and so far
you've demonstrated no skill with anything other than some alluded-to
ability to substitute programming for hardware you admittedly don't
understand and don't want to "take a lifetime to learn", or something
like that.

That's a real twisted interpretation of what I said there John. You
might be surprised by what I've been able to glom together over here.
I've even used a few transistors, op-amps and other icky analog stuff.
I'd like to see you search a Dallas 1-wire bus using a bunch of 74xx's.

The projects that I've built are a wee bit more complicated than the
project at hand. They would have been quite difficult to do without a
micro. I'm not saying that they couldn't be done, but they'd have been
real tough even by your standards I think.

I don't make a habit of bragging, but you make me feel obliged to put
forth some kind of evidence of ability. Therefore here are some of my
completed/working projects that I did:

I did an ultrasonic range finder w/lcd display. No biggy, but I used an
op-amp and comparator. A pendulum clock beat analyzer w/lcd of course
w/more analog stuff. Gives ratio of tick/tock beats/min etc.. An IR
controlled temp sensor display that reported readings from various
sensors strewn accros a 1-wire bus onto a graphical LCD screen. This
uses cool looking OCR numbers created from picking apart MS Paint bitmap
files (one of my cooler hacks, I think). All I had for the display was
a datasheet.

I also did a phone line powered Caller-ID display with a software modem
(that was probably the busiest PIC program I ever wrote with multiple
ISR handlers). That worked ok, but it was never quite perfect (in the
pure sense of the word). Since I don't have a DSO or logic analyzer I
could figure out what the problem was. I chalked it up to eronious zero
cross detects from 60HZ common mode noise on the phone line. Working
with phone line powered stuff is a real pain since you can't ground
anything. It was >99.9% correct, but that ain't good enough when one
bit error wrenches it up in a major way.

My recent ultra low-power project is a temperature data logger that
takes samples every 30 seconds and writes them to a 24C512. There is a
DS1307 RTC and an LM34. The sleep current is <5uA and the average
current is <200uA. I didn't think that was too shabby given the I2C
parts, the LM34, the RTC, the Vref for the ADC and the fact that it woke
up every second to see if it was time yet. You may think otherwise. It
also has a serial interface to pull the info out of the eeproms and to
set the clock/sample rate etc...

I have done many other projects as well, though many of them were never
committed to a permanent circuit board. Since the software is the key
part, they can be easily reproduced if needed. Most were built just to
see if I could "make it work", or to try communicating with some new
protocol (I2C, 1-Wire, SPI etc...) or to utilize some internal feature
of a PIC (CCP, ADC, UART, PWM, etc)

On a side note, I also did build my own 8052 BASIC computer using an
ATMEL 89c52, a surplus latch and 32K SRAM chip. Of course I flashed the
chip myself using the freely available image. I used a 373 as I didn't
know about the 573 latch. Lots of jumpers but it fits on a smallish
radio shack experimenter type circuit board. :-( Pretty neat when the
welcome message first came out. ;-)

Feel free to demand any sort of proof you need to back up these claims.
I have plenty of source code to show you and I could probably even take
a few pictures if necessary.
---
It's not a straw man at all.
When you insist that using a µC is a better solution than using
"discrete" logic, then if that insistance bears fruit, the requirement
for the equipment necessary to implement your solution will become
de rigueur. If the breadth of the project is the yield of a single
unit with a cost basically down in the noise compared to the required
expenditure in time and money to complete the project, then doesn't it
seem stupid to you to do it that way when doing it in hardware would
be so much faster and less expensive?

As I already said about this, yes it would be stupid to learn an
unecessary procedure for a one-off project. But then it would be stupid
to undertake the project under those conditions anyway (single unit,
super low cost). You can hardly justify the expense for any toolset
under those conditions. You seem to view the micro learning as a per
job expense, and I see it as a per life expense. As weve covered
before, the only dollar cost in PIC development is in the programmer
(and maybe the software that runs it). The rest of the devtools kit is
free. So all I see is a $75 expense and some hours to learn about
it(which a hobbiest, that's all it's about). Perhaps I am prejudiced
since I have 25 years of "professional software design" experience. ;-)

You haven't seen any of my work, so what qualifies you to judge it? But
that's what prejudice is all about, isn't it?

How so, if I code it up and flash the chips for him? Who's going to
"hand me my ass" then?
You really ought to follow your own advice, hypocrite. You telling me
to stop trying to control things around here is you trying to control
me. Friends I've got. Insignificant gadflies like you I don't need.

Only making an observation, carry on as you see fit. Or is that me
telling you what to do again?
---
Other than your just being obstinate, I fail to see why, (without
even going into the learning curve part of it) you think that paying
money for dev tools which will only be used once is better than not
having to pay for the dev tools, yet winding up with exactly what you
want anyway.

That was never my argument. That's the argument you keep making back
because that's all you think you hear from me. I wouldn't suggest
someone buy dev tools for a one time simple project like this. In fact
I wouldn't suggest that they buy much of anything as the cash outlay for
minimal equipment is still ridiculous for a project like this. I would
suggest they find someone that can do it for them and pay them.
---
That's a good point but, bottom line, you still save about 50 cents if
you don't do it with a micro and you don't have to learn how to do it
and buy all the stuff to do it with if you're not going to do it
again.

How many people learn to program a PIC for one simple project and then
never use them again? That's got to be a fairly small number.

Not too stupid to see that you put forth numbers massaged to further
your personal agenda.

You just called me stupid, yet you don't even bother to comment on this.
---
Dumbass, the OP over on SED wasn't interested in spending a great deal
of time and some bucks on learning how to design a µC timer; what he
wanted was something quick and easy which he could solder up, probably
on a piece of perfboard, which would do what he wanted. That's what
he got, and I got private email from him thanking me for the circuit
and letting me know that he'd let me know how it worked out. Rest
assured that I'll post the good news when I hear it.

Yes, we will all be duly impressed that you successfully designed a
ripple counter to reset a router once an hour. Perhaps you can get
another patent.
Now, do you have any comments on whether it'll work or not? Why don't
you build one and find out? It'll only cost you five bucks or so and
we'll learn whether you know how to solder or not. Or wire-wrap. Or
whether you're just plain ol' fulla shit.

The soldering part was cute, but I'm not just out of school. I've
actually been soldering for a "little while" now. Never was really
interested in wire wrapping, to messy. I do allot of solderless
breadboard stuff though. They're great for knocking out PIC projects.
 
J

John Fields

Jan 1, 1970
0
The point had nothing to do with whether it worked or not. The point
was your mistake, or "trypo" as you like to call them.

---
I think I already admitted that but, just in case you missed it, here
ya go: I made a typographical error. Happy now?
---
I never bothered to look that close. Obviously Fred is well aware that
you often post non-working circuits.

---
Well, since this _is_ an electronics group, I post circuits. Some
have technical errors in them, some don't. They usually get fixed.
The point is, _I_ post circuits. You, OTOH, critique typos when
someone catches you in a technical error.
---
It might be different if I was actually looking for errors in the
schematic, but I simply wasn't. I just noticed the glaring "trypo" in
the text.

---
More's the pity.
---


---
Perhaps that's because you aren't.

It's what I do for a living, so that makes it my profession. So I put
what I do in my .sig, what's wrong with that?

Interestingly, the fact that I do seems to thoroughly irk you since
you've mentioned it in a derogatory way more than once. Perhaps it's
because I choose to include "Professional" and you think that I should
be more humble and merely post "Circuit designer"? Perhaps you need
to get over yourself and come to the realization that not everyone is
going to accede to your whims as to what does and what doesn't
constitute proper behavior.
---
Do you think that I have no other skills, or is circuit design all that
is important?

---
What skills you may have, other than in electronics, are of very
little interest to me since, in these groups, what's important is
electronics and the ability to communicate. In seb, it's also
important to be able to render technical criticism
non-confrontationally in order to not scare off the newbies.
---
Kinda like the pretense where you come off as a civil human being?

---
I generally respond to civility with civility and to non-civility with
non-civility, and I very seldom make a non-preemptive strike.
---
Actually, I meant that in a gullable sort of way. I've got your number
now though.

---
Did you know that 'gullable' isn't in the dictionary?
---
Actually, I've been getting a kick out of watching you blow your top.
:)

---
Just a ruse to get you to bite, and now that the hook is set I own
you!
---

I seriously doubt that I'll be reporting back much of anything about any
of your circuits.

---
As do I. After all, it takes a modicum of acumen to do much more than
discover a typo in a technical article.
---
I do suspect that I will be hearing from you more often in the future though.

---
Perhaps.

I will say one thing now, though, and that is that after having
checked your posting history last night I found that you do seem to
know what you're talking about, technically, most of the time, so I
apologize for any inaccurate broad-brush slurs I may have made
earlier.

However, as far as the PIC VS "discrete" logic thing goes, you're
still all wet. :)
---



My comments in the original post were rhetorical, haven't you figured
that out yet?

---
Nope. Would you mind going back and dredging up those comments and
explaining what made them rhetorical?
---

What's to defend, I admitted my little faux pa.
[/QUOTE] ^^^^^^^^^
precedent
^^^^^^^^
someone's
their posts.

I didn't have to read 10,000 of them to figure out that you often go off
like this. Four letter words, invectives and ad-hominem attacks seem to
be a part of your regular forte.[/QUOTE]

---
Ahhh, you only read the juicy stuff. Try the tech, you might enjoy
it.
---

Really? Do ya think so?

---
Wellll... yeah.

After all, you say "WTF" so you can pretend that that's not saying
"What The ****", which is a pussy trait because pussies dont like the
"F" word, and you say that you don't use "cuss words" when the
acronym embodies the 'cuss words' you know the reader will expand
mentally to yield the 'cuss words' you want to wield, but can't.
So, your saying that you don't use 'cuss words' is a lie and lying is
another pussy trait.
---

As I said before, I didn't see a need to make a scene when I first saw
your mistake in SED. After that, when you posted your little trick
setup question in SEB, I felt a bit different. And then after Watson's
snide little remark about attrocious advice, I posted my little ^^^^^^^^^^
atrocious
sarcastic rant. And now here we are. Is that timeline really so hard
to grasp?

---
Certainly not, but it's not about a timeline, it's about changing
streams in mid-horse. What you said earlier, unconditionally, was that
you didn't feel it was necessary to make a scene, while what you're
saying now is that you're now attaching conditions which made it OK to
make a scene. Can't you see that that's an ex post facto violation of
the first statement by the second?

"Please, Mommy, Oh, pleeeease make him give me back my marbles...
---

See above.

---
See reply, above, to "See above"
---


As I originally posted in reply to your little trick query:

<quote>
Perhaps "dissipate more power" would have been more appropriate than
"hog more current".
</quote>

So as we can all plainly see, 'current hogging' is your own little
fabrication of terminology that I never used.
[/QUOTE]

If you think I'm running low on ammo, just keep posting. ;-) I could
care less how you run your business _or_ your life. That is until you
wish to horn into my life with your petulent, pedantic crap.[/QUOTE]
^^^^^^^^ ^
petulant cuss word

---
I don't consider B-Bs much of a threat, but I _am_ tiring of your
uninspired banter, so unless you can pick up the pace I'm outta here.
---

Do you think that you've somehow proved that I didn't know the
difference?

---
No. _You_ proved it with:

"Since there are two LEDs in series, one may hog more current than the
other resulting in its demise."

I merely asked a question designed to determine whether you did, in
fact, know the difference, but you took affrontery and refused to
answer it directly.
---
Again, like as stated earlier. I was originally going to say "juice"
not current and not power. Again, I wish that I had just so I could see
how you could have twisted that around.

---
Perhaps that's what you should have done. "Juice" is vague enough to
have covered all your bases and is a cutesy colloquialism, so I
probably would have just ignored it.
---
Is juice power, or is it current or maybe even energy?
Again, my original intent was not to use the word power either,
even though it would have been the "most correct" term.
Hard to believe that set you onto a personal crusade to prove me
a liar.

---
You've supplied the proof, I merely pointed out the incidents.
---

What type of reply do you think you deserve at this point in our
relationship?


Why do I think that no matter what I posted you would ridicule it?

---
That's not ridicule. I really don't think you know the difference and
I'm challenging you to provide proof that you do.
---
As you have so aptly demonstrated, you would leave no stone unturned in
order to crucify me.

---
Oh, Gawd... Now you're casting yourself in the role of Christ and I'm
pounding in the nails. Get over yourself.
---
Too funny.

---
Thanks. :)
---

I never said that I thought you were smarter than me. Only that you
knew more about electronics. Don't flatter yourself, there is a
difference.

---
Not so far.
---
Self important bullshit artist? That's got to be the most serious case
of projection I've ever seen. Do you see me waving my credentials
around? Do I have a sig line making bodacious claims?

---
Nope, but then, you've got nothing to make bodacious claims about.
---
That's not far from how I see things right now.

---
Ah, a double entendre; how delicious! Intended?
---
I don't know, what happened? How about you pick your own experiments,
and I'll pick mine.

---
Awww... baby demurs. And here I thought I was going to get to see
some good stuff.

OK, _I'll_ do it.

Here's the circuit:


E1
|
[R1]
|
+---->E2
|
[DS1]
|
+---->E3
|
[DS2]
|
GND

Unfortunately, the data sheet at the link you provided:

http://www.epitex.com/Catalog_PDF/08_Point_source_LED/L590CE-34F.PDF

doesn't show Vf min, and I couldn't find any Vf min for white LEDs so,
since you said that Vf can vary 2:1, looking at a Vf max of 4.0V for a
"typical" white LED at 20mA yields a Vf min of 2.0V. Also, 100mW
seems to be a pretty typical max dissipation, so if we redraw the
circuit with that in mind, and with LEDs with equal low Vf's we'll
get:


9.0V-+---->E1
|
[R1]
|
4.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


The choice of 9V for E1 is based on the assumption that E1 will be
regulated and will give 1V of headroom if DS1 and DS2 are both at Vf
max.

Now, since the current in a series circuit is everywhere the same,
solving for R1 with 20mA of LED current yields:

(E1-E2) 5V
R1 = --------- = ------- = 250 ohms
It 0.02A


and the LEDs will each be dissipating:


P = IE = 0.02A * 2V = 0.04W


so everything will be fine.


Now, though, let's select a high Vf LED for DS1 and see what happens.


Here's the circuit now:

9.0V-+---->E1
|
[250]
|
6.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


Since we now have a 3V drop across R1 the current will fall to:


E 3V
I = --- = ------ = 0.012A
R 250R


and the power being dissipated by DS1 will be:


P = 0.012A * 4V = 0.048W

So, if the LED is rated for 100mW max, it will be dissipating 48mW
and everything will still be fine, except the light output will
suffer.

If we have two Vf max LEDs in the circuit it'll look like this:


9.0V-+---->E1
|
[250]
|
8.0V-+---->E2
|
[DS1]
|
4.0V-+---->E3
|
[DS2]
|
GND


and the current in the circuit will fall to:

1V
I = ------ = 0.004A
250R

So, while everything will still be fine from a power dissipation
viewpoint, the light output from the LEDs will be greatly degraded.

Although it would be possible to fiddle with supply voltages and
series resistances in order to come up with a solution which would
allow a greater light output without overdriving the LEDs regardless
of the Vf spread, It would be more practical, IMO, to drive them with
a constant current.
---
 
A

Anthony Fremont

Jan 1, 1970
0
John Fields said:
---
I think I already admitted that but, just in case you missed it, here
ya go: I made a typographical error. Happy now?
---


---
Well, since this _is_ an electronics group, I post circuits. Some
have technical errors in them, some don't. They usually get fixed.
The point is, _I_ post circuits. You, OTOH, critique typos when
someone catches you in a technical error.

Well duh, that would be the appropriate thing to do wouldn't it?
It's what I do for a living, so that makes it my profession. So I put
what I do in my .sig, what's wrong with that?

Interestingly, the fact that I do seems to thoroughly irk you since
you've mentioned it in a derogatory way more than once. Perhaps it's
because I choose to include "Professional" and you think that I should
be more humble and merely post "Circuit designer"? Perhaps you need
to get over yourself and come to the realization that not everyone is
going to accede to your whims as to what does and what doesn't
constitute proper behavior.

Did I say that somewhere? Since you mentioned it, don't you find the
word professional to be tiny bit redundant? Why do you feel a need to
tell the world that you really do get paid?

Translation: Yes, you probably do know a bunch of stuff that I don't
know, but since I don't know it, it's not relevant.
electronics and the ability to communicate. In seb, it's also

Have I not communicated well enough?
important to be able to render technical criticism
non-confrontationally in order to not scare off the newbies.

Have you _ever_ seen me be confrontational to a newbie?

You probably meant preemptive (without the non).

Oh man, you're not going to start tossing spelling flames are you? How
lame.

ROTFLMAO, oh yeah I'm definitely hooked.

Modicum and acumen in the same sentence. No wonder it took you all
night to respond.
---
though.

---
Perhaps.

I will say one thing now, though, and that is that after having
checked your posting history last night I found that you do seem to
know what you're talking about, technically, most of the time, so I
apologize for any inaccurate broad-brush slurs I may have made
earlier.

However, as far as the PIC VS "discrete" logic thing goes, you're
still all wet. :)
---

OMG, I can't believe it. That must have been really hard. Maybe we can
coexist then.


OK, here we go:

First I said, "Maybe I could help make amends by belittling others,
nit-picking posts and posting a bunch
of OT crap?". Then I said, "Lets see if we can't get on to the road to
recovery now." That's all kinda the setup up indicating that sarcastic
and rhetorical remarks may follow. And then they did. I jibed Watson
since he tossed the first punch and you for what amounts to several
reasons (mainly your setup question when I've never slapped at you
before, I knew what you were trying to do and it torqued me off,
finally I've frankly found you to be a bit offensive lately and without
cause to other people namely Larry). So while it may not have been
entirely rhetorical, I really didn't expect this outcome.


sarcasm?

What's to defend, I admitted my little faux pa.[/QUOTE]

---
Then what was the reason for the sarcasm? Surely you realized it
would lead to no good.
---

^^^^^^^^^
precedent
^^^^^^^^
someone's
their posts.
[/QUOTE]

Why are spell checking my old posts now?

I've read some of it and you have your good side.
---



---
Wellll... yeah.

After all, you say "WTF" so you can pretend that that's not saying
"What The ****", which is a pussy trait because pussies dont like the
"F" word, and you say that you don't use "cuss words" when the

Actually I use the "F" word plenty well, I just tend to not spell it out
in usenet articles. Just trying to consider the children. ;-)
acronym embodies the 'cuss words' you know the reader will expand
mentally to yield the 'cuss words' you want to wield, but can't.
So, your saying that you don't use 'cuss words' is a lie and lying is
another pussy trait.

Interesting extrapolation you made there.

At the time that is how I felt. And then you changed all that when you
tried to bust my chops on current vs. power or "current hogging" as you
like to call it. So, you prompted the horse change, not me.
saying now is that you're now attaching conditions which made it OK to
make a scene. Can't you see that that's an ex post facto violation of
the first statement by the second?

"Please, Mommy, Oh, pleeeease make him give me back my marbles...

Yes, it's all about what serves your agenda best, isn't it?

If you think I'm running low on ammo, just keep posting. ;-) I could
care less how you run your business _or_ your life. That is until you
wish to horn into my life with your petulent, pedantic crap.[/QUOTE]
^^^^^^^^ ^
petulant cuss word

---
I don't consider B-Bs much of a threat, but I _am_ tiring of your
uninspired banter, so unless you can pick up the pace I'm outta here.
---

is

Do you think that you've somehow proved that I didn't know the
difference?

---
No. _You_ proved it with:

"Since there are two LEDs in series, one may hog more current than the
other resulting in its demise."

I merely asked a question designed to determine whether you did, in
fact, know the difference, but you took affrontery and refused to
answer it directly.[/QUOTE]

And I thought by saying "dissipate more power" that I made it perfectly
clear that I knew what you were hinting at. How direct does something
need to be before you can see it?

See, I knew I should have used it.

Do you really think that? I doubt that you do.

In my own simple minded terms, current is the rate of electron flow. X
electrons in Y amount of time. Power is just putting some voltage
behind it so that we have the rate that work is being done, energy is
just putting a time constraint on how much total power is available to
do work (i.e. a 12V 8AH battery contains 96WH of energy). Is that good
enough or do you want joules, coulombs and other textbook what not?


If that's how you feel, maybe you should listen to your conscience.

See, there you go making prejudicial statements again. You have no
idea.

---
That's not far from how I see things right now.

---
Ah, a double entendre; how delicious! Intended?
---
I don't know, what happened? How about you pick your own experiments,
and I'll pick mine.

---
Awww... baby demurs. And here I thought I was going to get to see
some good stuff.

OK, _I'll_ do it.

Here's the circuit:


E1
|
[R1]
|
+---->E2
|
[DS1]
|
+---->E3
|
[DS2]
|
GND

Unfortunately, the data sheet at the link you provided:

http://www.epitex.com/Catalog_PDF/08_Point_source_LED/L590CE-34F.PDF

doesn't show Vf min, and I couldn't find any Vf min for white LEDs so,
since you said that Vf can vary 2:1, looking at a Vf max of 4.0V for a
"typical" white LED at 20mA yields a Vf min of 2.0V. Also, 100mW
seems to be a pretty typical max dissipation, so if we redraw the
circuit with that in mind, and with LEDs with equal low Vf's we'll
get:


9.0V-+---->E1
|
[R1]
|
4.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


The choice of 9V for E1 is based on the assumption that E1 will be
regulated and will give 1V of headroom if DS1 and DS2 are both at Vf
max.

Now, since the current in a series circuit is everywhere the same,
solving for R1 with 20mA of LED current yields:

(E1-E2) 5V
R1 = --------- = ------- = 250 ohms
It 0.02A


and the LEDs will each be dissipating:


P = IE = 0.02A * 2V = 0.04W


so everything will be fine.


Now, though, let's select a high Vf LED for DS1 and see what happens.


Here's the circuit now:

9.0V-+---->E1
|
[250]
|
6.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


Since we now have a 3V drop across R1 the current will fall to:


E 3V
I = --- = ------ = 0.012A
R 250R


and the power being dissipated by DS1 will be:


P = 0.012A * 4V = 0.048W

So, if the LED is rated for 100mW max, it will be dissipating 48mW
and everything will still be fine, except the light output will
suffer.

If we have two Vf max LEDs in the circuit it'll look like this:


9.0V-+---->E1
|
[250]
|
8.0V-+---->E2
|
[DS1]
|
4.0V-+---->E3
|
[DS2]
|
GND


and the current in the circuit will fall to:

1V
I = ------ = 0.004A
250R

So, while everything will still be fine from a power dissipation
viewpoint, the light output from the LEDs will be greatly degraded.

Although it would be possible to fiddle with supply voltages and
series resistances in order to come up with a solution which would
allow a greater light output without overdriving the LEDs regardless
of the Vf spread, It would be more practical, IMO, to drive them with
a constant current.

So there we have it, the OP has been proven wrong. His LED's could not
have possibly failed.

I was honestly going to say that, but I didn't want to seem pretentious.
LOL

Yes, I'd agree that we buried your civility a good while ago.
 
R

Rich Grise

Jan 1, 1970
0
Anthony Fremont wrote:

In my case: 30 mA is max, so feeding them 22 mA shouldn't be that bad.
Moreover, the LED died when the circuit at
http://johnbokma.com/pet/scorpion/detection-using-uv-leds.html

was connected to 9V, or maybe even 7V (less then 12V anyway).

If you really used that exact circuit, with three LEDs in series
in each leg, then you have not killed any LEDs - 9V is simply
not enough to make them conduct. With three LEDS with a forward
voltage of 3.6V each, that's 3.6 * 3, or 10.8V, before any
current will flow at all. It's probably somewhat lower, but
once the forward threshold voltage is reached, the current
increases exponentially, which is why you limit the current,
and let the voltage find its own value.

Try two in series with a 91R resistor, as others have suggested,
or use a 12V source, like on the website, and put three in series
with 60 ohms - 62 is the nearest 5% value, I think.

Good Luck!
Rich
 
J

John Fields

Jan 1, 1970
0
Well duh, that would be the appropriate thing to do wouldn't it?

---
Precisely. My .sig reads 'Professional Circuit Designer' because
that's what I am. Your .sig, OTOH, reads... nothing???
---
Did I say that somewhere? Since you mentioned it, don't you find the
word professional to be tiny bit redundant?

---
Not at all. 'Circuit Designer" means one thing, Professional Circuit
Designer' means quite another. Perhaps you're miffed because you'd
feel ridiculous using 'Professional Hobbyist' as a .sig?
---
Why do you feel a need to tell the world that you really do get paid?

---
Actually, it's more of an ad than anything else, and has brought in
some work from time to time, so it's important in that sense.
---
Translation: Yes, you probably do know a bunch of stuff that I don't
know, but since I don't know it, it's not relevant.

---
Interesting that you find it necessary to try to put words in my
mouth. Sounds like you're so unsure of yourself that you have to
manufacture situations in which parts of imaginary conversations fill
in the empty spaces.
---
Have I not communicated well enough?

---
Obviously not well enough to put this matter to rest.
---

Modicum and acumen in the same sentence. No wonder it took you all
night to respond.

---
You were up all night just waiting for my response? How sweet!
---
OMG, I can't believe it. That must have been really hard.

---
For you, maybe, but not for me. Like I said before, if an apology is
warranted i'll offer it.
---
Maybe we can coexist then.

---
We'll see.
---
OK, here we go:

First I said, "Maybe I could help make amends by belittling others,
nit-picking posts and posting a bunch
of OT crap?". Then I said, "Lets see if we can't get on to the road to
recovery now." That's all kinda the setup up indicating that sarcastic
and rhetorical remarks may follow. And then they did. I jibed Watson
since he tossed the first punch and you for what amounts to several
reasons (mainly your setup question when I've never slapped at you
before, I knew what you were trying to do and it torqued me off,
finally I've frankly found you to be a bit offensive lately and without
cause to other people namely Larry). So while it may not have been
entirely rhetorical, I really didn't expect this outcome.

---
None of it was rhetorical, in that 'rhetorical' is defined as language
used for mere style or effect or language marked by or tending to use
bombast.

What you were doing was using sarcasm and invective vituperatively in
order to retaliate for your feelings of having been belittled.
---


Why are spell checking my old posts now?

---
I'm not _just_ spell checking your posts, I'm correcting your improper
use of the language in order to allow you to communicate more
effectively.

And because I feel like it.
---
Actually I use the "F" word plenty well, I just tend to not spell it out
in usenet articles. Just trying to consider the children. ;-)

---
How sickeningly pompous. If you don't want to use '****' when you
write, you don't have to blame it on the kids, just don't use it.
Besides, any "children" who hang out here have heard it all before
just in case you've been away from the planet for a while.[/QUOTE]

At the time that is how I felt. And then you changed all that when you
tried to bust my chops on current vs. power or "current hogging" as you
like to call it. So, you prompted the horse change, not me.[/QUOTE]

---
SWYMMD? ROTFLMAO!!!
---

Yes, it's all about what serves your agenda best, isn't it?

---
Of course. I should subjugate mine and hitch my wagon to your star?
---

And I thought by saying "dissipate more power" that I made it perfectly
clear that I knew what you were hinting at. How direct does something
need to be before you can see it?

---
I'm not sure you remember, but I didn't comment on your answer until
you started with your diatribe after I had the _affrontery_ to hit you
with a "trick question" and Watson _dared_ to throw that little barb
at you, and you're _still_ not over it. For an 'old hand' on usenet
you sure have thin skin!
---



See, there you go making prejudicial statements again. You have no
idea.

---
Ok, then, let's hear about your bodacity.
---
Awww... baby demurs. And here I thought I was going to get to see
some good stuff.

OK, _I'll_ do it.

Here's the circuit:


E1
|
[R1]
|
+---->E2
|
[DS1]
|
+---->E3
|
[DS2]
|
GND

Unfortunately, the data sheet at the link you provided:

http://www.epitex.com/Catalog_PDF/08_Point_source_LED/L590CE-34F.PDF

doesn't show Vf min, and I couldn't find any Vf min for white LEDs so,
since you said that Vf can vary 2:1, looking at a Vf max of 4.0V for a
"typical" white LED at 20mA yields a Vf min of 2.0V. Also, 100mW
seems to be a pretty typical max dissipation, so if we redraw the
circuit with that in mind, and with LEDs with equal low Vf's we'll
get:


9.0V-+---->E1
|
[R1]
|
4.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


The choice of 9V for E1 is based on the assumption that E1 will be
regulated and will give 1V of headroom if DS1 and DS2 are both at Vf
max.

Now, since the current in a series circuit is everywhere the same,
solving for R1 with 20mA of LED current yields:

(E1-E2) 5V
R1 = --------- = ------- = 250 ohms
It 0.02A


and the LEDs will each be dissipating:


P = IE = 0.02A * 2V = 0.04W


so everything will be fine.


Now, though, let's select a high Vf LED for DS1 and see what happens.


Here's the circuit now:

9.0V-+---->E1
|
[250]
|
6.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


Since we now have a 3V drop across R1 the current will fall to:


E 3V
I = --- = ------ = 0.012A
R 250R


and the power being dissipated by DS1 will be:


P = 0.012A * 4V = 0.048W

So, if the LED is rated for 100mW max, it will be dissipating 48mW
and everything will still be fine, except the light output will
suffer.

If we have two Vf max LEDs in the circuit it'll look like this:


9.0V-+---->E1
|
[250]
|
8.0V-+---->E2
|
[DS1]
|
4.0V-+---->E3
|
[DS2]
|
GND


and the current in the circuit will fall to:

1V
I = ------ = 0.004A
250R

So, while everything will still be fine from a power dissipation
viewpoint, the light output from the LEDs will be greatly degraded.

Although it would be possible to fiddle with supply voltages and
series resistances in order to come up with a solution which would
allow a greater light output without overdriving the LEDs regardless
of the Vf spread, It would be more practical, IMO, to drive them with
a constant current.

So there we have it, the OP has been proven wrong. His LED's could not
have possibly failed.

---
But since there _was_ a failure, if LEDs with the range of Vf's you
said was possible were hooked up as shown and the supply voltage and
series resistance were as shown, it would have been impossible for an
overcurrent situation to cause one of the LEDs to fail, so _your_
analysis of the failure mode was in error!

In all fairness, though, I don't recall what the situation surrounding
the failure was or anything about the circuit other than that it was a
couple of LEDs hooked up in series with a current limiting resistor of
some kind and a power supply. If you can supply the details we can
get to the bottom of it.
 
J

John Bokma

Jan 1, 1970
0
Rich said:
If you really used that exact circuit, with three LEDs in series
in each leg, then you have not killed any LEDs - 9V is simply
not enough to make them conduct. With three LEDS with a forward
voltage of 3.6V each, that's 3.6 * 3, or 10.8V, before any
current will flow at all. It's probably somewhat lower,

Yupm note that 3.6V is typical. And yes, the LEDs *do* burn on 7V, since
2V / LED = Vf min, which leaves 1V for the resistor, and hence: 1V/56
Ohm = 17.8 mA through each LED, which is well within range.
but
once the forward threshold voltage is reached, the current
increases exponentially, which is why you limit the current,
and let the voltage find its own value.

Try two in series with a 91R resistor, as others have suggested,

Uhm I think you misread their posts, or I did, I am not the OP.
or use a 12V source, like on the website,

It's mine, I did :). Ok I will describe what exactly happened: the
first LED that died on me: when I heated it (I thought I didn't solder
it right, "cold connection" (no idea of the right English expression),
so I made the solder melt again: LED worked (and all 3 in a row worked).
When I added more LEDs (I was building the circuit), and tested again: 3
LEDs didn't work, so I used the solder iron again on the suspicious
part: it worked. After a few attempts I gave up, and replaced the LED.

When I had finished the circuit and had it running for quite some time
(on < 12V), one row started to flash on and off several times (quite
rapidly, like a tube light starting), and then went off all together.
Same problem. I did a burn in test of the circuit for quite some time (I
am not sure, guess 12V or close, for one hour), and no other LEDs showed
the same problem. So out of 50 LEDs, 2 gave problems. I wonder if this
is "normal", ie: it is the quality of the badge?

Moreover, I bought a multimeter, and will check the voltage over each
and every LED, etc.
and put three in series
with 60 ohms - 62 is the nearest 5% value, I think.

68 as far as I know. However, I consider 56 Ohm well within range, since
the max current is 30 mA.
 
A

Anthony Fremont

Jan 1, 1970
0
I guess that means my ego gets enough to eat without me feeding it.

Those words are mutually exclusive, so yes I'd be embarrassed to call
myself that.
---
paid?

---
Actually, it's more of an ad than anything else, and has brought in
some work from time to time, so it's important in that sense.
---


---
Interesting that you find it necessary to try to put words in my
mouth. Sounds like you're so unsure of yourself that you have to
manufacture situations in which parts of imaginary conversations fill
in the empty spaces.

Pot, kettle black and all that.

I think we all could have appreciated you researching your case BEFORE
making it. Now you've gone and said all kinds of hateful, mean, and
ugly things to me just because I made one statement that really wasn't
all that bad.

And isn't that precisely what it did? Did you not feel personally
bombasted?
What you were doing was using sarcasm and invective vituperatively in

There was absolutely no invective involved. I merely posed a question,
it could have been phrased nicer, but it was just a question
nonetheless. Perhaps you should rethink that statement.
order to retaliate for your feelings of having been belittled.

Perhaps I should just send you a box of characters then you can
completely construct the sentences for me. That way you'll always know
what I mean.
And because I feel like it.

The children thing was just a joke, didn't you see the winkey?
Besides, any "children" who hang out here have heard it all before
just in case you've been away from the planet for a while.

Yes, well that certainly justifies it, doesn't it?

At the time that is how I felt. And then you changed all that when you
tried to bust my chops on current vs. power or "current hogging" as you
like to call it. So, you prompted the horse change, not me.[/QUOTE]

---
SWYMMD? ROTFLMAO!!!
---

Yes, it's all about what serves your agenda best, isn't it?

---
Of course. I should subjugate mine and hitch my wagon to your star?
---

And I thought by saying "dissipate more power" that I made it perfectly
clear that I knew what you were hinting at. How direct does something
need to be before you can see it?
[/QUOTE]

Exactly, that's the whole problem. You posted your "trick" question and
Watson saw it for what it was and made his snide remark. That directly
makes you the proximate cause of this whole fiasco. ;-)
at you, and you're _still_ not over it. For an 'old hand' on usenet
you sure have thin skin!

No, just a good recollection of what happened when.

I already did my bragging in another post that you have yet to respond
to.
..
---
Awww... baby demurs. And here I thought I was going to get to see
some good stuff.

OK, _I'll_ do it.

Here's the circuit:


E1
|
[R1]
|
+---->E2
|
[DS1]
|
+---->E3
|
[DS2]
|
GND

Unfortunately, the data sheet at the link you provided:

http://www.epitex.com/Catalog_PDF/08_Point_source_LED/L590CE-34F.PDF

doesn't show Vf min, and I couldn't find any Vf min for white LEDs so,
since you said that Vf can vary 2:1, looking at a Vf max of 4.0V for a
"typical" white LED at 20mA yields a Vf min of 2.0V. Also, 100mW
seems to be a pretty typical max dissipation, so if we redraw the
circuit with that in mind, and with LEDs with equal low Vf's we'll
get:


9.0V-+---->E1
|
[R1]
|
4.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


The choice of 9V for E1 is based on the assumption that E1 will be
regulated and will give 1V of headroom if DS1 and DS2 are both at Vf
max.

Now, since the current in a series circuit is everywhere the same,
solving for R1 with 20mA of LED current yields:

(E1-E2) 5V
R1 = --------- = ------- = 250 ohms
It 0.02A


and the LEDs will each be dissipating:


P = IE = 0.02A * 2V = 0.04W


so everything will be fine.


Now, though, let's select a high Vf LED for DS1 and see what happens.


Here's the circuit now:

9.0V-+---->E1
|
[250]
|
6.0V-+---->E2
|
[DS1]
|
2.0V-+---->E3
|
[DS2]
|
GND


Since we now have a 3V drop across R1 the current will fall to:


E 3V
I = --- = ------ = 0.012A
R 250R


and the power being dissipated by DS1 will be:


P = 0.012A * 4V = 0.048W

So, if the LED is rated for 100mW max, it will be dissipating 48mW
and everything will still be fine, except the light output will
suffer.

If we have two Vf max LEDs in the circuit it'll look like this:


9.0V-+---->E1
|
[250]
|
8.0V-+---->E2
|
[DS1]
|
4.0V-+---->E3
|
[DS2]
|
GND


and the current in the circuit will fall to:

1V
I = ------ = 0.004A
250R

So, while everything will still be fine from a power dissipation
viewpoint, the light output from the LEDs will be greatly degraded.

Although it would be possible to fiddle with supply voltages and
series resistances in order to come up with a solution which would
allow a greater light output without overdriving the LEDs regardless
of the Vf spread, It would be more practical, IMO, to drive them with
a constant current.

So there we have it, the OP has been proven wrong. His LED's could not
have possibly failed.

---
But since there _was_ a failure, if LEDs with the range of Vf's you
said was possible were hooked up as shown and the supply voltage and
series resistance were as shown, it would have been impossible for an
overcurrent situation to cause one of the LEDs to fail, so _your_
analysis of the failure mode was in error!

Oh, obviously. Yes they died after a time, but it had nothing to do
with too much dissipation. We know that, because the datasheet is the
end-all authority on the reality of any situation and that all parts
meet specs. Well, I'm sure glad that's finally settled.
In all fairness, though, I don't recall what the situation surrounding
the failure was or anything about the circuit other than that it was a
couple of LEDs hooked up in series with a current limiting resistor of
some kind and a power supply. If you can supply the details we can
get to the bottom of it.

You have access to the same material as me.
 
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