Newbie - Need help choosing film caps

[dizzy]

Hi,

I'm in the UK and looking at buying from http://uk.rs-online.com.

The problem i'm having is choosing film caps. There is so much choice i'm not sure what to choose?

e.g 330nf polyester film cap

http://uk.rs-online.com/web/c/passive-components/capacitors/polyester-film-capacitors/?searchTerm=330nf#sort-by=P_breakPrice1&sort-order=asc

Just trying to understand what package to choose and why?

Sorry for asking so simple a question.

[nocentelli]

For caps, there is an endless and unanswerable debate in DIY pedal building about whether the type of cap (I.e. ceramic,  multilayer ceramic, electrolytic, polybox, film etc) affects the sound in an audio circuit.... I wouldn't touch that discussion with a ten foot pole. For a beginner, the main criteria for choosing a cap type is which type will best fit the layout you are building, and can you get the value you need in the size you need. Post the layout you're planning to build, or a link to it, and we'll have a look and tailor our advice accordingly.

[dizzy]

This is the PCB i'm building:

PCB (pic shows 2 pcb's, so you can see front and rear)


OFF BOARD WIRING


SCHEMATIC


GENERAL INFO ON OPAMP and DIODE CHOICE FOR THIS CIRCUIT
http://moutoulos.com/oscommerce/product_info.php/cPath/1_8/products_id/30

[dizzy]

Whats the difference between:

THIS
http://uk.rs-online.com/web/p/polyester-film-capacitors/3121582/

AND THIS
http://uk.rs-online.com/web/p/polyester-film-capacitors/2980009/

[Kevin Mitchell]

For folks like us it's really down to budget and eye appeal. There are circumstances where the quality of a part is something to consider. But for now use what you can!

Those box film caps are near identical. Just manufactured a little differently. Same capacitance = same thing to me 

You could find something cheaper! As long as the spacing is appropriate for the pcb. But yeah... either one of those box film caps should work for that project - unless I'm mistaken for assuming so. But I doubt it 

[dizzy]

Thanks for the info.

Where is the best place to buy from? in the UK.

[bluebunny]

Check out Bitsbox.  Good prices, quick delivery and the range isn't quite so infeasibly vast as RS, so picking something appropriate doesn't take days of research.  Specifically, here are the film caps.  Bob will have most of what you need for stompboxes.  Tayda too (generally cheaper, but less speedy).

[ElectricDruid]

For folks like us it's really down to budget and eye appeal. There are circumstances where the quality of a part is something to consider. But for now use what you can!

Those box film caps are near identical. Just manufactured a little differently. Same capacitance = same thing to me 

You could find something cheaper! As long as the spacing is appropriate for the pcb. But yeah... either one of those box film caps should work for that project - unless I'm mistaken for assuming so. But I doubt it 

I agree with Kevin. Either of those you posted is fine, as are a ton of other options.

I'd add that tolerance is a useful criteria - +/-5% is a improvement over +/-10%, and one reason you'll pay more. Also I'd avoid capacitors rated for hundreds of volts - there's no need after all. 63V or 100V rated is plenty.

Tom

[antonis]

Dizzy, you have to communicate with Greg Panagiotou and tell him to correct it's schematic (Power Supply + goes to pin 8 and NOT to pin 7..) 
(these "cheap tricks" for not effective circuit reproduction make me mad.. - I would talk to him but I don't speak Greek.. )

You may also put a 100nF Ceramic (disk) capacitor between + & - pads on PCB - it's close enough to pin 8 for the purpose of supply decoupling..

[dizzy]

Can you elaborate on

(these "cheap tricks" for not effective circuit reproduction make me mad)

what do you mean by that?

He speaks english better than I do.

Is the problem just on the schematic? The PCB is correct?

[antonis]

Yes, the PCB is correct - as far as it concerns IC suppling..
(I didn't check the entire PCB - but I presume that it's already tested by Greg..)


< off topic - on>
I didn't intend to refer on his English language skill - it was a kind of joke because both of us are Greek..

As for the "nasty trick", it's a common method for somebody to "protect" his own work from been succefully copied..
<off topic - off>

[dizzy]

Cool,

Thanks for all your help guys.

I understand what to look for now:
- Physical size
- Tolerance
- Voltage ratings
- Cost

Other than that for effects pedal use they are the same.

And thanks for the info on where to buy from.

[PRR]

> what to look for now:

Traditionally, the old-time pedal companies picked parts this way:

1)- Cost
2)- Cost
3)- Cost
4)- Voltage ratings
5)- Physical size
6)- value in the ballpark (0.05, 0.68, 0.1 may all work good enough)
7)- Cost

If they walked (no internet orders) into their supplier and 0.05u 16V film was $0.39/each, but there was a crate of surplus 0.068 35V marked-down to $0.13/ea, they would make the 35V parts fit any way they could.

I know that in one-off DIY you are not suffering to save 26 cents. But this isn't like building rockets or cellphones.

> buying from http://uk.rs-online.com

As a beginner, I strongly suggest a Pedals-Parts source. You may pay a little more, but they won't be listing thousands of parts to confuse you. In the US, Small Bear is one of many fine on-target pedal specialists. Dunno who is good in UK/EU but I know there are many.

There are also the far-east suppliers who offer bottom-price parts with maybe slow shipping and sometimes hasty picking (send the wrong part). Economical but you should know what you want before going there.

[Kipper4]

Welcome Back PPR.

Welcome Dizzy.

Bitsbox is good. Nice prompt service.
Tayda (thailand) is better for cost and lots of stopmbox stuff. It takes about two weeks to deliver to the UK. Std postage. Special discout codes every few moths too usually @ 15%.
Keep an eye out in the tayda thread. or like them on facebook for notifications.

Rapid gets good reviews too.

Once you get a feel for common parts for stompboxs theres always auction sites too.

Have fun and good luck with the build.
Rich

[bloxstompboxes]

YAY! PRR is back! Hooray! Glad to see ya again dude.

[dizzy]

I went with Tayda, mostly on price.

Enclosures, especially seemed cheap.