Well, it's that time again! I'm buying more stuff!
I need to buy some capacitors (as I own none), and I was wondering what were common values that would be useful (similar to 330R and 1KR for resistors).
I was looking on eBay for a "lot" of assorted capacitors, but the only seller at a reasonable price is in Canada, and I'm too lazy to wait for that shipping.
If someone could suggest some values, I'm sure I could assemble a group with a seller on eBay.
Thanks! ;D
1uf
0.1uf
0.01uf
4.7uf
10uf
47uf
...
I suggest not buying too much. Especially aluminum capacitors are very fast (they last for something like 5 years).
And I suggest buying good ones from distributors like digikey, farnell or similar. Since there is much counterfeiting out there.
If you wanna buy good ones, get the Panasonic FM or FK series, they are normally used for computer motherboards and just excellent (low ESR).
Ceramics last for ages.
Especially aluminum capacitors are very fast (they last for something like 5 years).
Fast? Five years? Where are you getting those facts from, the internet I bet? ;D
Lefty
yea there is this thought on the internet that electrolytic caps are 100% garbage and they die in 6 months
Yes they leak and die after time, like 20 years, but it depends on how much environmental stress they take too, I have a apple //c made in 1986 and almost all the electrolytic caps in it are stock to the computer ... works fine, whereas people with macintosh G5's are experiencing failure now because of the high heat and no tolerances in voltage
Thanks for the advice.
It's a shame that people are cheaping out on components these days..
It's a shame that people are cheaping out on components these days..
Manufactures of electronic components have made great improvements in quality as well as lowering of cost in real terms over the decades. Most problems associated with early component failures has to do with not understanding or ignoring the specifications when selecting components. If you need a cap to work under elevated temperatures then it's up to the person selecting that to understand the requirements and understand the specifications of the components he/she selects, because proper components are available for almost any environment from outer space to the front end of a oil drilling bit. You get what you pay for and it's up to you to know what you actually require Vs the cost of a specific component. One can also over pay for specifications not required in a specific application, and a engineer is suppose to understand that it's his job to select what is required, no less or more.
Reminds me of a engineering joke I read somewhere long ago.
A optimist will say the glass is half full
A pessimist will say the glass if half empty
A engineer will say the glass is twice the size as required
Such problems are almost always the result of human error, neglect or bad economic decision making. I would place most problems with the design rather then the component manufactures. However bad batches of components have and will be made from time to time, but blaming components as being "too cheap" should not be one's first guess at what the root of these failures are.
Lefty
aye, my statement does not reflect apple used cheap components, they just failed to design outside of perfect conditions, thus short component life inside one of the most hostile pc interiors ever made
most hostile pc interiors ever made
Sounds like the plot to a new reality show ;D!
I suppose if you're building something that complicated, it takes a LOT of planning, and mistakes (or poor judgments) are bound to be made.
it takes a LOT of planning, and mistakes (or poor judgments) are bound to be made.
Lots of times its a 'rush to market' pressure that causes these kinds of problems to creep out. If proper prototyping and environmental testing and ample burn in testing is performed, these 'mistakes' can often be found and corrected before jumping to volume manufacturing and shipping to the end user. If you want to understand why military and NASA equipment is so expensive, just look at the testing requirements and specifications that the manufacture must meet and perform. It's not all just extra profit because it's gov'ment paying. 
Lefty
Lots of times its a 'rush to market' pressure that causes these kinds of problems to creep out. If proper prototyping and environmental testing and ample burn in testing is performed, these 'mistakes' can be found and corrected before jumping to volume manufacturing and shipping to the end user. If you want to understand why military and NASA equipment is so expensive, just look at the testing requirements and specifications that the manufacture must meet and perform. It's not all just extra profit because it's gov'ment paying. Wink
Lefty
Well put. That would indeed account for a lot of problems people have.
I work in the compliance industry (telecomm compliance), and I can confirm that compliance testing is expensive.
Everyone needs one of these:
A optimist will say the glass is half full
A pessimist will say the glass if half empty
A engineer will say the glass is 6dB down
A engineer will say the glass is 6dB down
;D
Well it would be 3dBs down actually as 3dBs is a half.
10log( 0.5) = -3.0102999566398119521373889472449
Doh, misquoted good old Dave Jones... I'll go watch this week's EEVBlog now
Well it would be 3dBs down
Wouldn't it actually be 3db up as the glass capacity is twice the water volume?
Lefty
Quite right the glass is 3dBs up but more importantly:-
The beer is 3bBs down, 
As a recycler of parts from project to project... I can assure that Electrolytics last more than a few years as stated. Maybe an audio DIY guy would disagree... but here in Arduino land... capacitors are not items with mysterious and magical qualities that can only be judged by ears and not test equpment or devices that contain a special pension plan equivalent to how much you spend on them.
So my advice, is... buy what you can afford and recycle what you can for your junkbox.