Re: 12 LED resistance circuit help


"John Fields" <jfields@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:fe8q61pdi7787n4c5c2sqvsqhj77nb9vrf@xxxxxxxxxx
> On Mon, 25 Apr 2005 00:43:35 GMT, "Anthony Fremont"
> <spam@xxxxxxxxxxxx> wrote:
>
> >
> >"John Fields" <jfields@xxxxxxxxxxxxxxxxxxxxx> wrote in message
> >
> ><snipped a bunch more side-stepping and invective/ad-hominem crap>
>
> ---
> Translation: "The sonofabitch nailed me, so I'll just shout one more
> insult and pretend he didn't. And now for something completely
> different..."

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

> >> ---
> >> HC4066, about 50 cents, cap about a dime, resistors about a nickle,
> >> diodes about a nickle so, for a one off, that's about $0.70.
> >
> >Didn't you have a pot in your design?
>
> ---
> Yeah, but it was a nicety. For the cost-conscious, and if the period
> isn't all that critical, 510k +/- 5% will be just fine.

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

> >> PCB, transistor, relay is a wash for either system.
> >
> >Probably wouldn't need a transistor to drive the relay as long as
> >5V@25mA will do it. Why not a nice SSR instead?
>
> ---
> Oh, I don't know... Maybe because that's not what the OP of the thread
> in sed you referenced asked for?

An SSR doesn't qualify as a relay?

> >> A one off for a micro is gonna cost you the micro, a programmer, a
> >> learning curve and programming and debugging time.
> >
> >How come the full cost of a programmer and the micro's entire
learning
> >curve gets factored in every time a micro is mentioned as a solution?
>
> ---
> Because if you haven't bought/built one and you haven't been through
> the process, then you'll have to buy/build one and go through the
> process if you want to play.
> ---

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.

> >It's a one time cost, just like the rest of anyones test equipment or
> >education.
>
> ---
> Yes, of course, but it's a one-time cost and an ongoing effort which
> will will be unwarranted if the goal at hand is to build a one-off
> widget with a total cost of, say, $10 or less.

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

> >I spent less than $75.00 on my programming hardware and the
> >dev tools were free from Microchip. My scope cost me more than $400
> >fifteen years ago and it was used then. Nobody worries about the
> >thousands of dollars needed for the rest of the stuff you need to
> >effectively tinker in electronics, just the $50 for the programmer
like
> >it's some kind of major show-stopper.
>
> ---
> The keyword there is 'tinker'. If that's _your_ bent, then fine.
> Spend away. Understand however, that that's not _everyone's_ cup of
> tea and that some folks only want a simple, inexpensive, easily
> realizable solution for a problem peculiar to them. Asking them to

Well, I guess that I see PIC chips like you see 74xx's

> spend _anything_ on hardware which is going to gather dust after the
> project is finished is, at best, stupid. As is asking them to spend
> time learning how to use it, and to acquire the software skills
> necessary to bring the "project" to completion.

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. 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.

> >IME, debugging time for this
> >project would be virtually non-existent and the end result would be
more
> >useful since it would have a much greater dynamic range on the time
> >constant.
>
> ---
> If you think the OP was wrong in asking for what he wanted, then why
> don't you get your ass over to sed and tell him about it instead of
> sitting here playing self - aggrandising games and kvetching about
> every goddam thing under the sun?

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.

> Hint: He doesn't _want_ to be able to change the timing, he just
> wants something that'll give him a contact closure, repeatedly, every
> hour or so.
> ---
>
> >> You figure it out.
> >
> >Your cost may be a little less assuming a PIC 12Fxxx (~1.20 single
qty),
> >but a 4 bit micro would change that.
>
> ---
> YAFI, LOL! Suggest away, and don't forget to include the cost of the
> programmer and the dev tools, and the time required to learn how to
> use them and to learn the instruction set.

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.

> >Outside of the minor cost
> >difference, I still feel that the micro offers far more potential for
a
> >better end result.
>
> ---
> "Minor cost difference"? You're either trying to sneak some shit in
> there or you can't do, or haven't done, the arithmetic, so I'll do it
> for you: Since the transistor, the base resistor, the clamp diode,
> the relay and the PCB are a wash, what's left is $1.20 for your
> suggested PIC way VS about $0.63 for my way.
>
> That comes to:
>
>
> $1.20
> -$0.63
> ------
> $0.57
>
> which is about 1/2 as expensive as your way. "Minor cost difference"?
> I think not.

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? It's really not very attractive watching an
engineer play games with numbers like he's doing Enron's books.

> Hmmm... Where did I read this:
>
> "BTW, I feel that a microcontroller would be a simpler, cheaper, more
> reliable (iow better) solution to the problem of resetting the network
> appliances on a regular basis. What do you think?"
>
> 1. Cheaper? I've just proven that it's not cheaper in onesies, and I
> doubt that with that huge cost differential it could be made cheaper
> in volume.

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?
According to Digikey, the fairchild 4060 is 77 cents in single qty, the
ST part is 55 cents each.

> 2. Simpler? Since the µC way would require a large investment in time
> in order to climb the learning curve, that can hardly be considered a
> simpler solution for a one-off.

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.

> 3. More reliable? I don't have a good handle on the reliability of
> either way, so if you have some numbers to back up your position, post
> them.
>
> 4. What do I think? I think you're full of shit.


.

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