What happened to Phil Allison?

You're bringing back memories of my younger years!

I made a position sensor years ago using a pair of tweeters that was capable of 25khz and a dual 555.. One section operated the TX while the other (RX) was used as the phase shift against the first unit on the echo. Of course, I had to add other components.. ;)

It worked very well for what I was doing at the time how ever, I had to stop using it because the frequency was bothering my dog I had then when ever she would pass by it..

In any case, it did work.. I also experimented using the same base idea for a Doppler speed meter which seem to be to subjective to surroundings.

Jamie.

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" Bottom line, I like 555s because their cost is low, they are quick and simple to implement, and they are *reliable* at doing many of the 101- plus things that a child can do with them. "

Plus 555s are easy and cheap to obtain if the circuit fails. It's easy to find a new 555, hard to find some custom programmed logic chip. I like making things that can be easily fixed if they break.

-Bill

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Monostgables depend on comparing a slow ramp with a reference voltage, and consequently tend to be messed up by electrical noise. I've used lots of them, so I'm well aware of this weakness.

No, but the chance that a 555 would be the best solution is pretty low, while the chance that some clueless amateur would think that the

555 was the best solution is relatively high.

-- Bill Sloman, Nijmegen

That part you got right!

I would agree with that, but with qualification. If I break something by being a klutz due to working on something past 2 AM or rushing a prototype that is running late for a trade show, I accept that I like easily-replaceable components.

In a trade show rush however, component cost matters little. Getting a prototype to work for the show is worth a few orders of magnitude more.

But once something that showed well at a trade show goes into production, what matters on products that I work on is performance, reliability and low cost.

Favoring reliability favors at least some usage of legacy workhorses that have a good track record of doing well until they are unable to compete on such basis. Favoring lower cost favors at least some usage of circuit designs and components that the designer is already familiar with, so as to reduce time wasted to learn how to use something newer that achieves only slight improvement.

One more consideration - cost of producing a product, including cost of developing it? If the product is developed in expectation of annual sales in the millions, higher development costs including higher development team payroll is more allowable to squeeze out 1/100's of pennies here and there in per-unit production cost, as well as more-optimized PCB layout to minimize whatever such as RFI or to make a power transistor run a couple degrees cooler.

But if the project is expecting annual sales in the thousands to 10's of thousands and faces major competetion in part from price even in a niche market, its development needs to be done on a budget. Profit is achieved there by doing a fair amount of "quick-and-whatever" working with what has good track records, including "devils that the designer knows" as opposed to ones that need to be learned.

--
 - Don Klipstein (don@misty.com)

Not that I even think of a 555 as a monostable, based on how I have seen that thing described.

Furthermore, I have used 555s for purposes not involving comparator of a ramp to a more-steady voltage.

Further-furthermore, why should a 555 be worse than alternatives for usage of a ramp signal? How is a 555 worse than a 40106 as a Schmidt trigger inverting buffer, other than having 1 rather than 6 of such?

As I have recently posted, I beg to differ. Especially for lower development cost in some cases and production costs in a few more, especially if designed by "old farts" that make use of time-tested workhorses that are the "devils that the designers know".

"Learning new devils" is extra cost. Often, the budget there is limited. To significant opportunistic extent, bids to make money are won by showing low cost of components plus cost of development.

There are ones that make money with electronics design with time-tested workhorses (both specific components / type-of-componets, and circuit designs that use such) that cost little to recycle.

I do that to get nickels rolling in, millions of them so far despite having a non-electronics "day job". After-taxes left me enough to own and operate and pay insurance on automobiles ever since I learned to drive one at the ripe old age that I had 14 years ago about twice the age allowed my way to sign full-blast contracts and drive motor vehicles on highways without parental sign-off.

Can you achieve a profitable business getting even 1 case of beer annually by eschewing the 555 from the kiddies that make use of it, or anywhere elsehow with electronics?

Oh, how about making some profit from a fun hobby? That has at least a bit of requirement to compete against whatever-others, such as the ones that I know in my electronics "side job". Even if that is improvement in bicycle headlights that outspread only a little, and LED work lights that in recent years ???maybe???-guesstimating achieved goodly-profitable worldwide sales in recent years getting into the 10,000s annually. (Professional automotive tools, as opposed to a cheaper thing that Sears or Home Depot or Lowes sells, and at this moment I am in a good mood to compete against those with "legacy components" except that my time is limited and I use it where it suits me well, in fair part financially.

--
 - Don Klipstein (don@misty.com)

--
Even though you continually pat yourself on the back for being
competent in the use of the English language, it seems reading
comprehension has tripped you up again in that I said: "I'd be 
willing to bet that Dr. Camenzind is flabbergasted, and immensely
pleased, with the ways his baby has been put to work." 

Notice that I used the present tense, indicating that I was talking
about now, not then.

In any case, from page 11-3:

"The market reaction to the 555 timer was truly amazing. Art Fury
made history by bringing out the circuit at an unprecedented low
price, 75 cents. I had deliberately made the design flexible, but nine
out of ten applications were in areas and ways I had never
contemplated. For months I was inundated by phone calls from engineers
who had a new idea for using the timer. To this day the 555 has been
the best-selling IC every year, copied by numerous companies. Except
for a CMOS version, the design has never been changed."

Notice the use of phrases like "truly amazing", "ways I had never
contemplated", "inundated by phone calls", and arguably the most
interesting: "To this day the 555 has been the best-selling IC every
year, copied by numerous companies.", which must certainly gall you.

The point here is that even though he doesn't state it explicitly, his
feelings were certainly those which accompany being flabbergasted,:

http://www.merriam-webster.com/dictionary/flabbergasted

So I'd be willing to bet that if were to be asked if he was
flabbergasted back then, his answer would certainly be in the
affirmative.

As for being immensely pleased, one would have to be rather thick to
presume he wouldn't be.

Oh, wait...

. . .

--- Consider a resistive load being driven by an N-channel MOSFET common-source switch:

+15V E1 | [150R] R1 | D Q1 CLK>---G Nch S | GND

With CLK being a square wave capable of fully enhancing and fully depleting Q1, the average power dissipated by R1 will be:

E1² 225 P = ----- = ------ = 0.75 watt 2R1 300R

Modifying the circuit so that it becomes a half-bridge and adding a negative supply gives us:

+15V E1 | D Q1 CLK>---G Nch S | R1 +--[150]--GND | ___ S CLK>---G Pch D | -15V E2

where for complementary square-wave drive and symmetrical supplies, the average power dissipated by R1 will be:

E1² P = ---- = 1.5 watts. R1

Now, in the case of a full bridge:

+15V E1 | +------+------+ | | D Q1 D ___ CLK>---G Nch Nch G---CLK S S | R1 | +----[150]----+ | | S S ___ CLK>---G Pch Pch G---CLK D D | | +------+------+ | -15V E2

the power dissipted by R1 will be:

(E1 + E2)² 900 P = ----------- = ------ = 6 watts, R1 150R

which is four times the power available from the half-bridge and 8 times the power available from the simple common-source switch using, instead of a horribly expensive infinite-voltage power supply, two simple 15V sources.

--- JF

The malignant spirit is now possessing Archie according to my exorcist tracker thingy.

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I never said that it was. Anything that relies on a slow ramp approaching a threshold has the same problem. =A0

Who cares?

But one that no serious designer of electronics can avoid. I spent roughly thirty years keeping a eye out for new devices, and every now and then one would look as if it offered a better way of solving a problem than the solution I'd found earlier.

t, bids to make money are won by showing low cost of components plus cost o= f development.

But if there is a better/cheaper component that you don't know about, your bid is dead in the water.

ed

If electronics was your day job, you'd be exposed to a much wider range of components, and might be able to get a bit closer to the state of the art.

Not in the Netherlands.

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Whatever works for you. I wouldn't have clue what that particular market wanted, and even less of clue how to find people who might be willing to sell something that I'd developed into that market.

And I don't seem to get excited about circuits that don't fit into something that could be broadly described as a scientific instrument, probably because that is the context in which I've worked since about

1965.

-- Bill Sloman, Nijmegen

te:

Wrong. Your OP was driving the sounder in a Morse code practice rig.

The power he was interested in was that of the acoustic signal being generated. Doubling the voltage swing across the sounder doubles the excursion of the diaphragm, and quadruples the acoustic power being transmitted. The power being dissipated in the transducer would - as you say - only be doubled, but it isn't a parameter of any particular interest, unless it gets it hot enough to burn it out.

I did notice this when I was doing my little bit of number crunching, but ressolved the apparent contradiction by reminding myself that the transducer was effectively AC-coupled to the OP's ear.

-- Bill Sloman, Nijmegen

--
Ooops...

The P channels should be on top, the N channels on the bottom, and the
drive signals adjusted accordingly:

        +15            +15
         |              |
         S              S
   A>--G PCH          PCH G----G NCH          NCH G--

--
Yes, I'd forgotten that.

But, so much the better in that he could have eschewed the bridge and
used a single 555 with a dual supply and gotten the boost that way.

Still, two 555s and a single supply seem to be more attractive to me.
That is, unless one happens to have, say, a +/- 5V supply laying
around.

All in all, I think the point has been made that 555's are extremely
versatile and useful (not to mention cheap) chips and are in no danger
of going belly-up in the foreseeable future.

Ok, but that doesn't answer the question. If it does the job, whatever weakness the monostable it has is irrelevant. However, I think I found the answer in your reply to Don. Your interest is in scientific instrumentation, so the noise would preclude that chip for you.

Well, you're not qualified to say that, until you consider the market and the product. I think you look at this from a different frame of reference, based on your experience in the scientific instrumentation over the years. "Best" does not necessarily mean technologically superior. The vast majority of consumers do not use scientific instrumentation. "Best" includes financial as well as technological consideration. The "best" dsp is not required for a cheap radio. The "best" _______ (fill in the blank) is *most* often not a requirement.

The fact is, wherever "best" fits into the discussion in your view, that the 555 is hugely viable commercially, no where near obsolete.

Anyway, I think I understand your point of view, and it seems too narrow to be valid as applied in general. And, it is also specious to conclude that a designer is a clueless amateur because he/she chooses a 555 for an application.

Ed

I did about 15 years ago. For a small signal conditioner/logic analysis project. Goal was to combine the output from 12 different laser sensors (2 channels per sensor) into five different outputs. Used a 556 to get two different clocks, one about 1KHz, and the other about 200 Hz. They clocked some Moto debounce chips to clean up the signals, and to provide a fixed delay. Design also used several EPROMs as async combinatorial logic...

Charlie

I've never used an asynchronous EPROM that way. IIRC I first heard about it in the "CMOS Cookbook", before PALs existed. Back then I also used data-selector logic, where I with a CD4067 116 analogue MUX, I could get any logical combination of (gasp) _5_ inputs with a single chip!

That actually allowed me to simplify the hot-swap logic in the first civilian bidirectional direct-broadcast satellite system (Spacetel from AEL Microtel) which was introduced at the end of 1983 or early 1984.

Every central-office board had to have that logic, but they didn't think to standardize it, so everybody just rolled their own. My boards were the first to be released to manufacturing, and I had circulated my design in an internal memo way in advance. Of course, since I was a

22-year-old new hire at the time, nobody listened AFAIK. Some of those designs were real rococo stuff.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

One of my teachers in digital logic had just 'mentioned' it, in passing during our combinatorial logic days. I had six weeks to get a proto done and tested, an EPROM programmer, no PAL programmer, and no MCU experience, so if you got a nail, use a hammer!

Basically, I needed a separate 2in-2out state machine for each sensor. EPROMs had 16 bit address and 8 data out, so folded the outputs to 8 of the inputs, and each EPROM could do four sensors, so I needed three EPROMs. The fun part was creating a BASIC program to calculate all the values, and output them into a format that the EPROM programmer would understand...

Charlie

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One 555 (or any other cheap and nasty astable) and a complementary pair of MOSFET switches would have got twice the acoustic power from a

5V rail.

You've managed to convince me that you didn't know that the 555's totem-pole output doesn't pull all the way up to the positive supply rail. Similar sorts of ignorance and idleness mean that there is still a market for 555 in notionally new designs (which are - in general - old designs being recycled long past their sell-by date).

Human stupidity and idleness are going to be with us for a while yet, and the 555 is in no danger of losing its market in the meantime.

The 555 is still totally obsolete, and anyone who finds a 555 in something being touted as a "new design" should be deeply suspicious of the quality of the design and the designer.

-- Bill Sloman, Nijmegen

--
Got a schematic?

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(Don

Granting the number of gaps in the logic you have posted in this thread, you don't need any extra breaks. You do all doddering that's going on around here, and your pathetic faith in the continuing utility of the 555 is a particularly blatant dodder.

-- Bill Sloman, Nijmegen