Bad Circuits in the Wild

Pretty much. Though a nice REAL technical question could elicit some replies.

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: "skypeanalog"  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
         America: Land of the Free, Because of the Brave

You mean if it's on the internet, It may not be true?....I'm shocked, simply shocked!

I don't know what the motivation would be but surely many of these circuits are crap or, at best, incomplete.

Also, if you ask for recipes from famous restaurants or chefs which many people do, they often give a phony or doctored recipe and not their award winner or money maker. The happy home maker comes way thinking she's got that special recipe from the five star restaurant but it never quite measures up when tries it.

I found it on the net so it must be true. :P

Yup..bad circuits can be like those recipes.. My fun conspiracy theory is that bad circuits on websites are a form of disinformation to confuse and slow down the competition. :P

I suspect some get creative with bad circuits and use'm like recycled waste product. I mean...What to do with a lemon circuit. Just toss it in the garbage?.. What a waste... All that design time lost.. Or put a bad circuit to some other use like perhaps:

• Show off technical level

• As website filler

• As bait to sell advanced designs

• As bait to sell revisions

• Get more consultation $$$

• Increase website traffic

• Fool your competition

I believe it's a 'Got lemons...Make lemonade' mentality that spreads some bad circuits on the net..

D from BC British Columbia Canada

I think I know what you mean. Usually I end my posts with a question.. The Q for this post is . 'Are there reasons for designers to deliberately put bad circuits on the net?'

D from BC British Columbia Canada

I mean are there sneaky reasons...

D from BC British Columbia Canada

Lots of people like to play with electronics, but a tiny minority are good circuit designers. Hell, a tiny minority of EE graduates are good circuit designers.

I feel bad for the guys (almost always guys) who think they can build something cheaper than they can buy it, who don't know much about electronics, and who find atrocious circuits on the web. Circuits are, to some people, like the magical incantations in a Harry Potter book.

Some things, like woodworking or cooking, practically anyone can do usefully first try, and improve on incrementally. Electronics is a lot harder.

I do give away circuits now and then, even to competitors, just not the few crown jewels of our products.

John

I agree with the last sentence, but sometimes there are good reasons to give stuff away. I tend to do give most things away because my living is more closely tied to the creation of intellectual property than to trade secrets, but even more because I've watched a lot of people's projects go down the tubes because they didn't know how to get the circuits part right. That sort of unnecessary waste and suffering offends me.

Cheers,

Phil Hobbs

This pre-dates the web.

It typically starts off as a poorly proof-read or prepared publicity release.

This gets bound into a catalog, shortly after which the author implodes.

Then it gets republished without technical proof-reading, in subsequent volumes under different acquisition company logos, to include revised packaging formats, and part ordering numbers, which are non-searchable or never actually produced.

Then it gets re-formatted electronically, or otherwise, using temporary summer students.

Somewhere along the way, critical parts (including the headliner) become obsolescent or are just simply dropped, while the circuit drawing continues proudly on.

RL

Yeah, but reality is that it's much more likely that people publish circuits that were "good enough" for their needs and then moved on. The real problem with circuits on the Internet is that in 99+% of cases you don't have the original problem statement but only a solution; for the casual puruser after awhile it's usually some self-evident whether a circuit was some quick little hack or if extra effort went into making it more robust.

Most circuits posted come from people who've never considered whether they have lemons, rotten apples, champagne or something inbetween.

As Joerg is fond of pointing out, sometimes really "crude" designs are driven by extreme cost-cutting measures, such as that microcontroller board that had software carefully crafted to always maintain the appropriate load on the power supply to avoid the need for a regulator. Stop the CPU and -- poof! -- it goes up in smoke. Similarly you see all those designs where some well-engineered circuit could replace and end up being cheaper than a more expensive "brute force" approach by someone who's lacking the design skills for the former.

For example, I can design and build my own bench supply. Make one?.. Absolutely not! Waste of time and money. I can't even buy 2 power transformers without exceeding the price I paid for the power supply (from E*bay).

Electronics design reminds me of plate spinning.. :P Quickly found an example :

D from BC British Columbia Canada

Ahh..so that's why some circuits look bizarre. The circuits may have been shaped by tight budgets,time frames, deemed 'good enough', of brute force or were a match to a unique problem/situation (later omitted).

'..and these parts were used because I pulled them out of tv. It would take too long to order.. These parts were leftover from another project and these parts were samples....' :P

D from BC British Columbia Canada

Which may contain errors as well.

My guess is that it is mostly hobbyists that post schematics If you do a little digging you'll find some of my old diagrams as well. It is amazing how many people copied my 8051 midi-keyboard design onto their own web page :-)

Anyway, just look at the circuit in the 'PWM motorcontroller' thread. It shows a typical circuit lacking a lot of things a real motor controller should have.

As long as you regard circuits found on internet as incomplete design examples and do your own 'homework', you'll be fine.

--
Programmeren in Almere?
E-mail naar nico@nctdevpuntnl (punt=.)

[snip]

No. I suspect what you suspect as "deliberate" is probably "ignorance". The one copy they built works. You'll note that, when I criticize such designs, I catch all kinds of flack. There seems to be more interest in "minimal" parts than in performance :-(

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: "skypeanalog"  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
         America: Land of the Free, Because of the Brave

You see that a lot in old magazines like Popular Electronics... they denote various non-critical components "junkbox parts" that they assume you'll have lying around. (And there actually is value in trying to let people know which components are critical and which aren't!)

Some of the old circuits books like those from Forrest Mims stated something along the lines of, "every circuit in this book has been built and tested with real parts..." -- Something a newcomer would think would be true of all published circuits, before they were burned a few times. :-)

You can find IEEE journal articles where people come up with "novel" circuit ideas that don't appear to have been physically built, instead just being run through a simulator. Kinda a little scary, IMO...

You can console yourself with the thought that, if anything, software design is even worse? :-)

Big schematics frighten people. :)

D from BC British Columbia Canada

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Your transistors are a lot cheaper than most of ours, Jim. :-)

Certainly any decent engineer genuinely wants to receive constructive criticism regarding their design, although human emotions being what they are it can be difficult to do so in a way that doesn't offend. This has several root causes:

1) The person receiving the criticism has to genuinely believe your goal is to improve the end result and not just make them look bad. For people with a bit of a paranoia streak, this can be all but impossible. 2) Public schooling in the U.S. today seems to be so focused on just "getting the kids through" and having them "feel good" about themselves that objective feedback on their performance is uncommon (rather than failing kids, the classes get dumbed down!). This leads to the third problem... 3) Many people have an overinflated view of how good they are at something. I'm amazed at how many companies I'm familiar with or have worked with honestly think they're doing "cutting edge" development when, in actuality, it's all well-worn territory to anyone who cares to do a little research. People don't like having this brought to their attention! ...or, alternatively, a little humility goes a long way. (I formerly had a co-worker who used to say, "We're not as cool as we think we are!")

You (in particular) also seem to get dinged at times for criticizing without providing alternatives. I seem to recall your stating this approach is meant to get people to do a little more thinking/research of their own which -- while an admirable goal -- is not the kind of thing someone with a tight deadline wants to hear. :-)

---Joel

That pwm motocontroller post made me start this thread. :)

D from BC British Columbia Canada

Sno-o-o-o-o-ort ;-)

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: "skypeanalog"  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
         America: Land of the Free, Because of the Brave

Why do I need to make someone "look bad"? After all I AM the great exulted one (smirk ;-)

That is for sure, and it's a great shame.

Kill all the lawyers... then ALL the managers ;-)

I hope I didn't do that to someone who was really trying to make schedule. It seems the usual request comes from a student who thinks you don't need to study and make mistakes and learn and make mistakes and... (*)

(*) When I was a young engineer, in my 20's, I'd work at home evenings, sitting on the living room couch with a quadrille pad on my lap, doodling ideas, wadding them up and tossing them over my shoulder into the dining room.

Our barely one year old daughter (now 46) would proclaim how I was going to "be in trouble with Mommy" ;-)

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: "skypeanalog"  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
         America: Land of the Free, Because of the Brave