(newbie) Ordering Parts

Hello all,

I just ordered my PCBs to build a few Green Pre's. I have several questions about ordering parts. Please bear with me

What do I do if the part calls for Polycarb, Polypropylene, Polystyrene, Polyester and only Ceramic is available?

How do I tell what the lead space is? 2.5mm/5mm etc... I don't see this spec on Mouser or Digikey?

Is there somewhere I can see part cross referances? I.E. 1nf = .001uf?

How do I learn about patterens? I usually only Radial, Axial etc. The part list I have has things like rad0.1 and rb.2/.4

How do I determine quality? What is WIMA? How do I know if the part is Good Quailty, etc?

How important is Tolerance and voltage rating?

Is it a good idea to order "extra parts" I.E. If I need 5 22pF, should I order say 10 to be safe?

Thanks!
KFG

Hey

[quote author="kungfugeek"]What do I do if the part calls for Polycarb, Polypropylene, Polystyrene, Polyester and only Ceramic is available?[/quote]

Ceramic will work.

[quote author="kungfugeek"]How do I tell what the lead space is? 2.5mm/5mm etc... I don't see this spec on Mouser or Digikey?[/quote]

Mouser usually let's you download component datasheets which have dimensional drawings.

[quote author="kungfugeek"]Is there somewhere I can see part cross referances? I.E. 1nf = .001uf?[/quote]

I'm not sure I understand this question...

[quote author="kungfugeek"]How do I learn about patterens? I usually only Radial, Axial etc. The part list I have has things like rad0.1 and rb.2/.4[/quote]

I would assume that rad0.1 means a radial component with 1/10th of a n inch spacing between leads. Don't know about that other one... measure the PCB, maybe?

[quote author="kungfugeek"]How do I determine quality? What is WIMA? How do I know if the part is Good Quailty, etc?[/quote]

There's tons of info on this all over the net. Do a search here for "choosing capacitors" or similar.

[quote author="kungfugeek"]Is it a good idea to order "extra parts" I.E. If I need 5 22pF, should I order say 10 to be safe?[/quote]

I usually do order extras to get a price break, but the chances of getting defective parts from a reputable dealer are, I would say, infinitesimal. If you're thinking of building some more stuff, definitely try to stock up on parts.

You'll love the green pre. Good luck! :thumb:

Peace,
Al.

[quote author="kungfugeek"]
Is there somewhere I can see part cross referances? I.E. 1nf = .001uf?

KFG[/quote]

microFarads (µF) nanoFarads (nF) picoFarads (pF)
0.000001µF = 0.001nF = 1pF
0.00001µF = 0.01nF = 10pF
0.0001µF = 0.1nF = 100pF
0.001µF = 1nF = 1000pF
0.01µF = 10nF = 10,000pF
0.1µF = 100nF = 100,000pF
1µF = 1000nF> = 1,000,000pF
10µF = 10,000nF = 10,000,000pF
100µF = 100,000nF = 100,000,000pF

Thanks guys! What about the tolerance and voltage rating question?

Higher voltage ratings on caps is fine-but the size of the cap may get too big for your pcb. Tolerance of what?

Joel.

PS for the Green pre's what I did the first time is look at Kevs parts list and checked at Jaycar to see a description and then knew what to look for at Mouser.

Mouser has polypropoline caps, etc.

Joel

[quote author="kungfugeek"]How important is Tolerance and voltage rating?[/quote]

You don't want to exceed the voltage rating on components. Tolerance isn't usually that big of a deal, with certain exceptions, like the 6.81K resistors that feed phantom power to the mic. Get those in .1% tolerance, or match two 1% resistors.

Peace,
Al.

On the topic of basic questions...

Is 2.2uF the same as 2.2mfd?

[quote author="MikoKensington"]Is 2.2uF the same as 2.2mfd?[/quote]

Nope. uF (or µF, really) means "microfarad" or 1 x 10^-6 Farads, while mF stands for "millifarad" or 1 x 10^-3 Farads.

Having said that, some people don't know any better and interchangeably use mF and uF... A real pain in the nuts :?

Peace,
Al.

[quote author="alk509"][quote author="MikoKensington"]Is 2.2uF the same as 2.2mfd?[/quote]

Nope. uF (or µF, really) means "microfarad" or 1 x 10^-6 Farads, while mF stands for "millifarad" or 1 x 10^-3 Farads.[/quote]
Yes, BUT mfd is the same as µF - it's an old way of writing it. 1mf = 1000µF = 1000mfd.

Best regards,

Mikkel C. Simonsen

You don't want to exceed the voltage rating on components.

Click to expand...

Why? I thought it was OK to go higher on voltage ratings, but the only problem was the footprint.

Joel

[quote author="Mbira"]I thought it was OK to go higher on voltage ratings[/quote]

Nope. If you put 100V across a 50V cap, it'll blow up.

Try it, t's fun! :green:

[quote author="mcs"]Yes, BUT mfd is the same as µF - it's an old way of writing it. 1mf = 1000µF = 1000mfd.[/quote]

Like I said on my first post, some people don't know any better and use the two interchangeably. Back when things were typed on typewriters, there was no mu character, so they used "m". That does NOT mean that "mfd is the same as µF". They're THREE orders of magnitude different!

Peace,
Al.

[quote author="alk509"]Like I said on my first post, some people don't know any better and use the two interchangeably. Back when things were typed on typewriters, there was no mu character, so they used "m". That does NOT mean that "mfd is the same as µF". They're THREE orders of magnitude different![/quote]
Read a bit closer - one is mf, the other is mfd. There is a big difference. MFD is an abreviation of microfarad, but mF is millifarad - not the same thing.

If you look at old American schematics, the caps are specified in mfd - not mf. And by mfd they mean microfarads, not millifarad.

Best regards,

Mikkel C. Simonsen

alk509,
Sorry, I wasn't clear, I meant the opposite. 50v going to a 50v cap or a 100v cap is fine. More voltage for the cap-not less.

Joel

Hi, newbie second class here. Forgive me if these answers are too basic.

Since your questions were all about capacitors, I've been told that caps have a +/- 10% tolerance rating. Can anyone confirm this?

I think "axial" means that the wires come out either end and "radial" means they both come out of the same end. For PC board-mounted stuff you usually want radial, unless it's some polystyrene part that's only available as axial, for example.

And before you give up looking for esoteric caps (the ones you can't find on Digikey or Mouser), give Google a try. I just googled "40uF polypropylene" and it took me right to the order page on partsexpress.com! Score! Just when I was about to give up.

Hope this helps, -jl

[quote author="synthetic"]Since your questions were all about capacitors, I've been told that caps have a +/- 10% tolerance rating. Can anyone confirm this? [/quote]
Polypropylene/polystyrene caps (or micas) often have smaller tolerances - 1%, 2.5% etc. Electrolytics are often -25/+80% or something similar...

For PC board-mounted stuff you usually want radial, unless it's some polystyrene part that's only available as axial, for example.

Click to expand...

For PC-board use, you'll need the type the board was designed for :grin:

Best regards,

Mikkel C. SImonsen

[quote author="mcs"]Read a bit closer - one is mf, the other is mfd.[/quote]

Doh! Didn't catch that

Peace,
Al.

Thanks to all of you for the information, it has been invaluable! I stumbled upon this website the other night, and it has a ton of great newbie information. Might want to add it to a newbie thread Meta. http://www.kpsec.freeuk.com/

[quote author="kungfugeek"]I usually only Radial, Axial etc. The part list I have has things like rad0.1 and rb.2/.4[/quote]

No one seemed to answer this. the BOM where it specifies cap type, Radials as "rad" and Axials as "axial" and then there's "rb." what type of cap is this?

Thanks Mikkel,

looks like this thread could help to confuse some newbies
a little knowledge is dangerous

where possible use the listed item until you have more understanding
ASK if you are unsure

from time to time you will see guys here substitute ... and often it is an electro for the next size up in both capacitance and voltage
electros are made smaller these days and so will fit
they are also made is slightly different standard sizes so going up to the next nearest value is a typical thing to do

some guys see it as an improvement to have a little or alot more capacitance in supply rails and also like to have higher temerature ratings

ASk when in doubt


rb / RB - capacitor is a cap with the legs at one end


RBLL - same as above but ... LL ... low leakage

ohhhh...
thanks Kev

there should be a Cap META