Capacitor values - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: November 11, 2009, 10:47:18 pm
content: Veteran EEs/hobbyists: I'm building up my supply of parts (wish there was a turn key way to purchase all the basics at once) and I'm finding it a little tricky keeping my caps organized because it's more difficult to determine their value - you need a loupe and a chart. Resistors I'm starting to just "Recognize" their values by their stripes, no loupe needed. Weird how that just happens.Do you rely on a cap tester to sort your caps when you return them to the filing drawer or do you just use the number or? What's your system.Sincerely,-Novice

author: Unknown
author_rank: Unknown
timestamp: November 12, 2009, 06:33:02 am
content: For leaded parts, I just look at the number, I know a say 103 is a 0.1uF cap.If you want some fun use SMD caps, all the ones in the "resistor" package eg 0805 etc have NO marking. I have most of mine on reels, but for odd values I would use once in a lifetime, I keep 50 on the shelf in a parts case, real pain as the carriers RS were using are plastic and it is hard to write on themIt is no more surprising that people can read resistors colour codes than we can read the alphabet, after all it is just a symbol the represents a value... It takes time to be able to instantly recognise, but it also took years for us to be able to recognise the alphabet when we were young (and we could learn things a lot quicker then)

author: Unknown
author_rank: Unknown
timestamp: November 12, 2009, 11:47:41 am
content: So for the easy ones, they're easy. But what about the harder ones that are difficult to read or just not readable - you just throw them away, and pull a new one off the reel?

author: Unknown
author_rank: Unknown
timestamp: November 12, 2009, 11:55:24 am
content: Quote from: bmwm3edward on November 12, 2009, 11:47:41 am#1 if they are on a reel, you know what it is#2 I have not seen any parts that have been hard to read.

author: charliex
author_rank: Frequent Contributor
timestamp: November 13, 2009, 04:46:47 pm
content: You can buy kits of caps and resistors in common values, digikey/mouser etc sell them, there are also some on ebay. Prices vary from good to stupid. They usually come in a neat compartment case.I buy the drawers and put new components in and label them, which is tedious at the start. I've been thinking of putting an LED matrix connected to the PC which i can type in a part search and it lights up the drawer where the parts are incuding xref, of course using a spreadsheet row/col would be a lot simpler.Some component packs use the ultra cheap components though and of course you might end up with a bunch of values or tolerances you never use, 'fillers'I always seem to be misisng one part, like the .1uF 0603 cap's i swear i had, so the kits are useful, just pick a range you'll use.For identification there is the smart tweezerhttp://www.advancedevices.com/products_tw.htmor even better the SuperProbehttp://mondo-technology.com/super.htmlwhich there are many variations of, its a cool little tool.

author: Zero999
author_rank: Super Contributor
timestamp: November 13, 2009, 06:25:06 pm
content: 103 is 10,000pF, 10nF or 0.01µF.104 is 100nF or 0.1µFComponents are generally only made in standard values called preferred values, a rounded logarithmic series, see Wikipedia for more information.http://en.wikipedia.org/wiki/Preferred_value#E_series:_Capacitors_and_resistorsCapacitors are normally only be found in E6 values for bog standard 20% and 10% tolerance ceramic and electrolytic capacitors, precision capacitors can be found in E12 values.If you're building a stock of capacitors then I'd advise getting an E3 set from 10pF to 10,000µF.For a stock of resistors 10R to 1M in E12 values is generally acceptable.

author: Neilm
author_rank: Super Contributor
timestamp: November 14, 2009, 05:28:36 pm
content: If you need help with resistor markings I would recommend a program called MiscEl. (http://miscel.dk/MiscEl/miscel.html) It not only translates colour codes and capacitor values - it will show basic RC charge curves, work out heat sink sizes, translate LED wavelengths into actual colours, work out how much current you can put through a wire or PCB track and a lot more beside. I use it at work and it is one of the best free gems I have ever found for electronics.

author: Unknown
author_rank: Unknown
timestamp: November 16, 2009, 08:24:34 pm
content: Fantastic info here. I ordered a crapload of resistors/caps and some odds & ends (crystals, diodes, transistors, etc) from some suppliers on ebay in mostly 100x units by every value I could find. Most 100x units were $3-$5 usd.Next step will be stock some drawers.Those smart tweezers look very cool, but spendy ($310 for the base model). Almost as much as that Rigol scope I just bought. The superprobe looks interesting and much less expensive, and a nice DIY project.I have a hard time reading the small caps (eg, tantalum) so the loupe needs to be close by. Might be faster to just probe it than read it.Thanks again for all the good info.

author: Zero999
author_rank: Super Contributor
timestamp: November 16, 2009, 10:34:20 pm
content: Here's a cheap E12 resistor kit.http://www.rapidonline.com/Electronic-Components/Resistors-Potentiometer/Carbon-Film-Resistors/E12-Series-610-piece-carbon-film-resistor-kit/74262Here are some capacitor kitshttp://www.rapidonline.com/Electronic-Components/Capacitors/Ceramic/224-piece-Ceramic-capacitor-kit/74260http://www.rapidonline.com/Electronic-Components/Capacitors/Radial-Electrolytic/120-piece-Electrolytic-capacitor-kit/74261

author: qno
author_rank: Frequent Contributor
timestamp: November 27, 2009, 06:15:25 pm
content: The smart tweezers looks like a nice subject for Dave to evaluate......I dont think you can take it apart easily though....

author: Simon
author_rank: Unknown
timestamp: December 08, 2009, 06:45:43 pm
content: I normally order stuff when I need it, I came back to the UK to live from abroad and started up with electronics again,As I started to design stuff I ordered the parts, not 1 of or whatever the project needed but 10-100, so I needed resistors to start, I got a pack with most of the range from rapidonline, I got a pack of caps from maplin (the worst electronics shop ever) and ordered pics and mosfets from various suppliers in medium quanties as I needed them. in this way i have gradually built up a stock which serves my purpose most of the time and when I need another thing i look up the chaepest supplier and buy 10-500 depending on the item and cost, it means some investment but better than paying through the nose for delivery everytime I need a couple of bits and i never run short

author: Zero999
author_rank: Super Contributor
timestamp: December 09, 2009, 12:12:28 am
content: I agree with the resistor idea but I don't see the point in using a differential amplifier which would just add more components.You could use a resistive divider with no other active components.I'd recommend using high voltage resistors which can withstand a peak of at least 1kV.The example shown divides the input voltage by five, I haven't read the datasheet in great detail so you might need a greater division than that: check the datasheet.Check the input impedance of the IC - you might need to take it input account, if so it'll be in parallel with the middle resistor.If the IC has internal protection diodes there shouldn't be any need for a MOV.