Locally, we have about 2800 licensed hams in the county, of which I would guess about 500 are at least semi-active, 100 regularly attend various club meetings, 50 bother to build things, and perhaps 4 are qualified to design anything useful. While it's possible to get some help with design and construction from ham radio, it really depends on whom you contact.
This is the age of specialization. I can design and advise on some aspects of RF and repair. In other areas, I'm clueless. You would do best by finding a forum, blog, newsgroup, or mailing list that covers the specific area that you're interested in asking questions. Don't be fooled by the names or lack of traffic. There are often forums where most of the answers are by email from those that just don't want their names and advice subject to public scrutiny. For example, I've found that the LEAST useful forum for solving Apple computer related problems is Apple's own forums. Just post your question and see what happens. If you get a dozen one-line useless bad guesses, move on.
As always, the quality of the answers depend heavily on the quality of the question. Without a clue as the nature of the question, vague answers, like this one, will be epidemic.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Right. Sure. Maybe in your small world. I recently went to the local ham radio club's hamfest. 99% of the items for sale were cheap chinese crap that is even cheaer on Ebay. the hams that knew what they were doing have either quit the hobby, or are now 'Silent Keys'. I saw more computer related items than radio, and the couple vendors with components had no one at their tables.
--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.
Just renewed my ticket for the 2nd time. You might find a few hams that dabble in design but only because that's what they do for a living.
The best way to learn besides OTJ training is to read. There isn't a day that passes that I don't read out of some old school books containing fundamental electronics. You need to understand why electronics work, and some mathematics involving calculating loads, current, power sine waves etc...first. I did it ass-backwards learning on the bench first using test equipment without knowing much about the fundamentals.
There are plenty of commercial FM radios around, and all the county radios are digital. The only amateur related emergency gear is the club's HF station, near the county offices. They don't have a spare tower, or antennas that could be erected in a couple hours and there is no way in hell they could put up a replacement commercial digital radio base station or cell phone tower, even if they had months.
--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.
Wrong. A pickup for a guitar doesn't require a stable reference voltage to regulate it's output.
Look at national Semiconductor's 'Simple Switcher' line, or Linear's free Switchercad spice program and use ICs that are tailored to SMPS applications. If your opamp circuit takes too long to stabilize, you'll have an expensive failure and maybe a fire.
Switchercad III can be downloaded here:
formatting link
There is a Yahoo user group at:
formatting link
--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.
But, isn't that so of everything? :> I enjoy watching folks "design by app-note" -- cutting and pasting together circuit fragments from various publications -- and wondering why their designs don't work.
"Um, if you UNDERSTOOD what you had /designed/, you would understand why it WON'T work!"
This is where The Trades have a leg up (in theory) on The Sciences. In the former, there is a hands-on learning process where you see the practical aspects of what you are learning *before* you are deemed "qualified" to practice that skill. In the latter, you get an abstract exposure to things (to be fair, often a wider range of "things" since "paper is cheap") but aren't qualified to use *any* of them before you are "certified" (diploma-ed).
:<
M Crichton's novels are typically based on this "lack of (full) experience" -- Man having "getting" technology before he has "earned" it (i.e., has the wisdom to know how to *use* it).
Expressed in your characteristic "dry" manner... :>
But, illustrates the point, well. Yet, doesn't say how accessible those "4" are nor where their interests lie. E.g., you would be hard-pressed to get me to help you design an audio amp out of discretes -- but, could probably keep me obsessed with trying to cut power consumption by half a milliwatt on a battery powered device! (and I'm a *helpful* soul ;-)
A lot also depends on how dense that population of "experts" is, as well. E.g., our county is 9,200 sq mi with a population of just over 1,000,000. So, 90 people / sq mile. *If* we have those 2800 hams, here (no idea), that would be one ham for every 4 sq mi. That can make accessing that "expert" a bit problematic (I find learning is usually faster "in person").
And, if the hams (and population, in general) are not evenly distributed throughout the county, it only gets worse (potentially). E.g., there are *no* electronic suppliers, here, within driving distance. The closest possible (overpriced) retailer is clear across town (and would never have the types of components that I am interested in).
Exactly! The days of being able to keep a drawer full of transistors, diodes, resistors, etc. and hack together an amplifier -- or a logic gate (!) -- are long behind us. Sure, you can still do it, but there is no point. I can recall building 8 digit counters out of discretes with nixie displays... would I bother wasting my time on that *now*?? (though I *have* been sorely tempted to build a Difference Engine).
Agreed. ------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Wear rubber soled shoes, remove all jewelry, keep one hand in your pocket and *play*! It's not *chemistry* where you have to worry about losing eyebrows or other body parts when you make a mistake :>
All you have to lose is a little *money*!
(and, depending on what you are playing with, many devices nowadays can take a LOT of abuse -- short circuit protection, etc. -- so you don't have to worry about replacing components every two ohnoseconds!)
Valid point, although I think you exaggerate a bit.
Now, give those same numbers for the denizens of sci.electronics.repair. Maybe two numbers, with and without the profuse few who insist on pushing the SNR toward zero.
I'd also like to hear your estimate of the percentage that even attempt to add USEFUL new information that helps answer the original question. Percentages by post will be different than percentage by author. And the percentage that just want to argue for the sake of arguing, name calling, backstabbing, "hey look how smart I think I am", etc.
On any subject, it's important to ask someone who knows what he's talking about. Unfortunately, there are precious few of them. Most get drowned out by the multitude. Some of them ARE hams.
When a few of us used to go in on a table at a hamfest we'd go dig in the attic or basement for a bunch of junk to sell. I used to go to Dayton Oh every year but that started being a joke. Most junk and computers. A few vendors from Kenwood, Yaesu, Alinco, MFD etc.. Not like it was 20 years ago.
Actually that's the US, and not here. In Israel there are 600 or so licensed hams, with about 250 in the IARC. With an almost 100% draft/national service, there is no need for hams as emergency communications.
There were about 50 to 100 more two years ago, but the government sent out bills to renew the licenses and they decided it was not worth the money.
There are plenty of radios in the government and IDF (military) and between previous experience in the military, annual reserve duty, and volunteer units (such as the border police, etc) there is absolutely no need for hams.
The other big privleges/service the hams did was phone patches, which have been obsolete since 1997 when the price of international calls became cheaper than cross country ones and cell phones became cheap.
In fact the IARC decided to do a drill this year just to do one, and they scheduled on the sabbath, which meant that 99% of the hams in Jerusalem and environment would not participate. It was like the ARRL scheduling a nationwide emergency drill without Maryland, Virgina, DC and so on.
They don't need one. The ARRL's purpose in these drills is to do "health and welfare" messages e.g. "your aunt Matilda's ok in a shelter, but her house washed away". This is to offload that work from NGOs like the Red Cross and Salvation Army, so they can provide relief services.
There also is no need to replace commercial digital radio base stations or cell phone towers, etc. There are plenty of people in the world who can do that, once the dust settles they will. It's the first few days that are critical.
If things work properly, then the hams come in provide communications in the background for the "victims" without getting in the way.
I know the hams here could not do it, and the ones that could would be back with their reserve units anyway. but here ham radio has never been much more than a hobby.
Going back to David's question, I pointed out ham radio because he could use it to connect with someone who did know what he wanted and would be willing to help him. Someone pooh-poohed the idea because they wanted one to one instruction, which they would not of gotten from a web forum, which was the original request.
It all comes down to expecting that someone who actually knows op-amps and is willing to answer questions about them is going to spend their time looking for and answering questions on a web forum.
99% of the questions asked on web forums are so basic that they are a waste of time to answer and the self proclaimed experts are unable to answer even those.
BTW, did Don Lancaster ever update his "OP Amp Cookbook"?
Geoff.
--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.
During which no one can help. A lot of radio stations lost their generators of STLS during the last round of hurricanes in Central Florida. The only news was via SW, but those services are no longer broadcasting to the US.
Few HF antennas survive a hurricane around here. Downed power lines and little fuel availible for generators. In some places, people with a working cable modem are the only outside communications, since the RR backbone is buried fiber optic and it covers large areas of the US.
I posted links to the proper Usenet groups, a free spice program and a Yahoo support group. I still don't like the idea of using an opamp in a SMPS.
Ask him. He posts on sci.electronics.design once in a while. His website is
formatting link
He put a few of his books online a while back and posted links.
--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.
I haven't been to the Dayton Hamvention in 25 years. Prior to that, I went almost every year, from the late '60s. I lived closer to Cincinnati, and hit about five hamfests each year, except while on active duty. The only hams in that area that knew electronics both worked for R.L. Drake in Miamisburg, and they frequently asked me for help. I repaired a lot of older ham gear, including some homebrew with no documentation. I also worked at Cincinnati Electronics on the PRC-77 manpack radio doing QA.
--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.
On 3/20/2011 1:10 AM Michael A. Terrell spake thus:
How did you miss that I specifically requested an online forum, not other Usenet newsgroups? It's right up there in the very first sentence I wrote, for chrissakes.
--
The phrase "jump the shark" itself jumped the shark about a decade ago.
- Usenet
Getting a "Technician" license would require about an evening of your time -- plus travel to/from exam. And, I think, $6 (?) exam fee. No need to set up a radio, etc. Just like getting a driver's license doesn't require you to own -- or even DRIVE! -- a car.
[But, I understand your point...]
You have access to all the same media with a ham license. The point is, you (can) "hang with a different crowd". Hopefully one that, at a minimum, knows that electrical power is measured in Watts, inductance is expressed in Henries and that a current of
2 amps flowing through a resistance of 3 ohms develops a potential of 6 volts.
I.e., questions that separate the "men" from the... um... I forget...
[I think that about sums up the Technician Class, eh? :> ]
A good bit of the license information deals with *regulations* and conduct/expectations/responsibility/etc.
I don't think the license itself will buy you anything towards your goal (though, as an aside, you might consider downloading the question pools for the various license classes and wading through the "technical" questions /cold/ to get a feel for just how much you actually already *know*. This could be encouraging -- or discouraging -- to you.)
Rather, the real value is getting you exposed to that sort of person. Sort of like hanging around a sports bar (instead of a LIBRARY) if you are interested in learning about sports...
The EEVblog is headed by Dave Jones, an EE in Australia. The forum is for beginners and experienced EE's and anyone interested in electronics design and hardware (test equipment, etc).
Be that as it may, I went ahead and joined the first forum that was suggested here (Electro-Tech Online,
formatting link
and whaddya know, I got answers--pretty good ones--within an hour that allowed me to get parts of my project working. Maybe it's not the definitive, be-all and end-all of understanding op amp operation that you seem to be suggesting, but that isn't what I asked for anyhow. I'm just trying to muddle through at this point.
Actually, I have a pretty good textbook which probably has all the answers I need, if I can only understand them: Albert Malvino's /Electronic Principles/ (actually fished out of a dumpster!). It's extremely well-written and explains all about op amp operation, including the four feedback configurations (SP/SS/PP/PS), calculating gain and impedance, and various op amp applications. Now if I can only get over having to deal with the math (ugh!) ...
--
The phrase "jump the shark" itself jumped the shark about a decade ago.
- Usenet
On 3/19/2011 9:09 PM Geoffrey S. Mendelson spake thus:
Interesting suggestion, but highly impractical for me for several reasons.
First of all, it would require a whole 'nother pursuit--getting the license AND acquiring/building/setting up a radio rig, which is definitely *not* what I'm the least bit interested in at this point.
Then there's the problem of the medium. Web fora are perfect for my porpoises: I can easily send text and images, and receive the same. With radio, I'd have to exhaustively describe every little detail of what I'm trying to do. And unless I had some kind of radio-fax setup, whereby I could transmit images (and images of extremely shitty quality at that), how would I exchange schematics with other hams? Email? or, ironically, posting them on the Web?
Sorry, not a good suggestion. I will say, though, that I do have a copy of the ARRL Handbook (1991) which has been quite useful, if a bit out of date.
--
The phrase "jump the shark" itself jumped the shark about a decade ago.
- Usenet
No, quite the contrary. If you know *everything* about op amps, then there is no difference between applications -- because you already know all the little details that differentiate one type of application from another.
My point was, if you find a group that is dealing with the same types of applications that you are wanting to address, then they will have already tweaked the "oversimplification" of what an op amp is by appending "... except, you have to do ________ when you use it *this* way _______" to that description. I.e., they will have highlighted the details that are important in *that* type of application (e.g., if you are running with a single supply instead of balanced supplies, needing more voltage compliance in your output than the op amp can provide, etc.)
Most of "design" is figuring out which details to *ignore* and which to *pursue*. A group of folks working on similar applications will have already sorted that out for you.
[I recall designing (passive) speaker crossover networks with a friend at school. He always had "50 ..." as his expressions. I finally asked him where the heck he kept coming up with this "50"?? Ans: 2 * pi * 8 ohms (more or less)
D'oh!
I started with Senturia & Wedlock's _Electronic Circuits and Applications_ (and, before that, just reading data sheets). It was one of those "good" books that predated the "sold by the pound" trend that seems to have infected "modern" writing :< (though it was $20+ about 35 years ago!)
There also were "Made Simple" books aeons ago (When Dinosaurs Walked the Earth). These were the precursors of the "For Dummies" books -- but infinitely more intense! Highly condensed but very good to get exposed to a lot in very few pages. (e.g., "Electronics Made Simple")
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.