Electronics > Beginners

Hello, advice on my lab, and what solder to buy please

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mariush:
You could just order 25-50-100pcs out of every capacitor you need.
You won't need 170 unique values, just limit yourself to the most common, like the E12 series for example: https://en.wikipedia.org/wiki/E_series_of_preferred_numbers#Lists

    E12 values (10% tolerance)
        1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2

    E24 values (5% tolerance)
        1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1

So for example get 10nF, 12nF..82nF,100nF, 120 nF .. 820nF , 1uF, 1.2uF, 1.5uF...8.2uF, 10uF....100uF
We're talking about maybe 12x3-4 = ~50 unique resistor values.

Use NPO/COG for very low values, X7R/X5R for let's say anything above 1uF ... voltage rating 25v or higher,  that's what you'll probably get in 0805 package

If you check tme.eu you can quickly select 12 values and the voltage range and the quality (npo/cog/x7r/x5r) and then sort results by price for the qty you plan to get.
It would take you maybe 1h or so to pick all of them.

You can also pick more of the ones that are often used like 100, 220, 330, 470, 820 ... i'd say these are the most common used.

Above 10uF, consider electrolytic capacitors or polymer capacitors. Aim for 105c rated, low impedance capacitors... lots of kits will have general purpose capacitors which often aren't suitable to repair electronics but can be used in hobby projects.

tooki:

--- Quote from: HobGoblyn on January 01, 2020, 11:36:43 pm ---I’ve now ordered everything recommended in this thread:)

Looking forwards it all turning up.  I got all 4 of the tools tooki linked to on  Reichet’s site, I also ordered the flux and crispers mariush linked to.

Also got most of the other bits and pieces (still have a few test leads to get)

So far my only slight annoyance is that one vid I watched suggested getting an 0805 sample book, I found the following on eBay

https://www.ebay.co.uk/itm/0805-Practical-SMD-1-Resistor-And-Capacitor-Kits-Pack-Box-Component-Sample-Book/312614474728?hash=item48c94653e8:g:aIkAAOSwnktc3nds

And stupidly didn’t read the description properly. It only contained resistors.  I contacted the guy and said I’m happy to keep it, but he should take the word capacitor out of the title, but his response was that the actual description was clear.  Personally,  as there’s only one book to buy (it’s not a listing with different book choices) , I disagree, but life’s too short to worry, will hunt eBay for a few cheap 0805 caps.

--- End quote ---
I did eventually buy an SMD ceramic cap kit, since I kept needing them, but consider instead just buying an empty SMD binder (as in, one with empty plastic inserts, just no components) and then ordering some of the most common values. I'd actually go even narrower than mariush suggests, like perhaps just 1.0, 1.5, 2.2, 4.7 per decade (with as many of the 1.0 as the other 3 combined). I find I use 100nF (104) more than anything else, but sometimes 10nF (103) and 1nF (102). Anything higher is electrolytic, and I just don't do the kinds of things that use smaller values. (Other than crystal oscillator load capacitors, which I just purchase as needed, since that's a relatively picky application.)


Actually this reminds me of one other suggestion I had: organization. How to store and organize tools and parts quickly becomes an issue. People have different ways of doing it, so just start thinking about it already — do you want boxes? Tubs? Drawers? Baggies? Binders? How will you label them — printed labels? Handwritten labels? Marker? And how do you want them sorted?



As for the ebay vendor... ::sigh:: Maybe try reminding them one more time that the description is accurate, but the listing title is not. I hate how the Chinese vendors pack their listing titles with all sorts of imprecise, related terms, rather than accurate ones so that you can exclude the stuff you don't want.

HobGoblyn:
Is the capacitor voltage simply the maximum voltage it can take?

In other words, is there any difference in using say a 200v or  100v or a 50v cap on a circuit that's less than 50v?

Thought I'd check before I order my 0805's :)

Many thanks
 

mariush:
Yes, the voltage rating is the maximum voltage the capacitor can handle.

With electrolytic capacitors, you may often see capacitors rated for higher voltage than needed because other technical properties of the capacitor are dependant on the internal volume of the capacitor.  So for example, on computer power supplies you may see 10v rated electrolytic capacitors on the 3.3v and 5v outputs, even though a 6.3v rated capacitor could have been used, simply because the 10v rated capacitor has the same diameter and it's maybe just a few mm taller, and due to bigger volume it may have lower ESR and higher lifetime rating.

Ceramic capacitors have capacitance that varies with voltage and temperature : a 1 uF 16v rated ceramic capacitor will not be 1uF  when used with 12v, it will be less.
See this PDF for a good explanation :
Temperature and Voltage Variation of CeramicCapacitors, or Why Your 4.7μF Capacitor Becomes a 0.33μF Capacitor
https://pdfserv.maximintegrated.com/en/an/TUT5527.pdf

For this reason and others, you will often see 0402 or 0603 16v or 25v rated ceramic capacitors used with 3.3v chips, for example, when 6.3v or 10v rated would be safe.

For decoupling capacitors (0.01uF, 0.047uF, 0.1uF for example) you may see even 35-50v rated capacitors used because the capacity is so small.

For ceramic capacitors I would say don't buy anything rated for less than 16v unless very expensive (ex 4.7uF ceramics may be expensive at high voltage ratings)
For electrolytic or polymer capacitors, I would suggest 35v or 50v rating for anything under 100uF as they're all gonna be about the same diameter (<8mm) and above 100uF,  the most common voltages are 6.3v (only useful to you if you'll want to repair electronics and you need to replace a capacitor and you can't use bigger capacitors) , 10v (can be used for any low voltage chip like 2.5v,3.3v, 5v, with lithium batteries etc) ,  16v (for use with 12v parts like fans, relays, computer power supplies) and less often  25v  (common in older lcd monitors and useful if you decide to power circuits with laptop adapters that output 16.5-20v)
 

later edit :

Also, you shouldn't be afraid of 0603 parts, they're just a bit smaller than 0805 and still quite easy to solder, even if you're older. 
0805 fits very well between 2 pins of a header with 0.1" space between holes, so they're great to use on prototyping boards or between pins of a DIP chip, but 0603 is also capable of this and just a bit smaller (with a bit extra solder on the pads you can easily use a 0603 instead of 0805)

The reason I mention it is because you may find 0603 much cheaper and easier to find compared to 0805, as factories most likely focus their production on smaller parts to sell more volume.  You may find you can order 100 or 250 pcs for the same price of 50 0805 parts, so it would be worth going with 0603 in that case.

Johnboy:

--- Quote from: HobGoblyn on December 29, 2019, 06:43:31 pm ---I've also ordered the following books:
Learning The Art Of Electronics, A Hands on Lab Course
Am about to order a 2nd hand 2nd edition of Art of Electronics

--- End quote ---

Just thought I should point out that "Learning The Art of Electronics" is the companion volume to the third edition of "The Art of Electronics" and not the second edition. The companion volume for the second edition is called "Student Manual for the Art of Electronics".

If you've already bought the books, don't panic. The third edition of the main textbook complements the second edition; a lot of people hang on to the second edition anyway, as it does contain some things that were not updated/added to the new edition (and a dedicated RF chapter in particular, IIRC). At one point during the writing, the 3rd edition was described by Winfield Hill as a sort of "additional" volume, rather than standalone ("keep your 2nd edition" he said), but from what I've seen of it they may have eventually dropped that angle. The first chapters of each, at least, are virtually identical.

As to the companion volumes:

I have not actually had a look at "Learning the Art of Electronics" to see what has been changed from the earlier "Student Manual for the Art of Electronics", but there are others on this forum who might supply that information. You may just have to do some hunting around within the newer lab manual to see what best applies to the layout of the older textbook.



Edited for clarity, name error

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