Replacing Eletrolytics with Non-electrolytics?

[bufftonz]

Hi everyone, I'm back again, for more education.

Is it really necessary to replace an electrolytic cap with a non-electroytic one? I mean...there is a capacitor that I am replacing that will be of .10uF valued, but I have never seen a 0.10uF electrolytic nor have I seen any in shops, which leads me to think that such small value is not a big deal for eleltrolytics? Is this true?  Here is the original circuit that I'm currently working on:

                                        22k          0.56uF
> (input from Chip)--------/\/\/\/\------||--------------------> (to middle lug of Echo Feedback pot)
                                 

Next below is the modified, variable-ized version of the same circuit, but with a pot, two caps-one that holds the least Bass tone threshold and one that holds the max Bass tone threshold for the echo repeats:

Note: It was suggested that 0.10uf is a good "least bass threshold" value and that 0.56uf (or 0.47uf) is a good "max bass threshold" value:


                                               0.10uF
>(input from chip)-----------------||------------------------------> (to middle lug of Echo feedback pot)
                                |                                           |
                                |                                           |
                                |  <---------|                          |
                                |               |      0.56uF          |
                                 ---------/\/\/\/\-----||-----------
                                               50K
                                            (variable)



I'll leave the 0.56uF in for max bass; however, for the "least bass" threshold value should the 0.10uF be an electrolytic or non-electrolytic? Would electrolycity matter for such a small capacitance value?


--Chris

[bufftonz]

Oh I also forgot to mention, the 0.56uF cap is electrolytic.

[Paul Perry (Frostwave)]

Use any kind of cap, just so long as it fits.

[bufftonz]

So basically what you're saying is that for small values below .20 (i.e. 10 uF), I would use any sor of cap, such as nonelectrolytic. But for the higher values i.e. .47uf or .56uf, I would be make sure to replace with same electrolyics? I just wanted to be sure, thanks.

--Chris

[petemoore]

  Cap: observe that it will not see overvoltage.
  Choose your Uf value.
  Install.
  Polarized caps can't be reverse polarized, that means polarity must be observed and followed, the negative side of the cap [marked with - or > or ->->] needs to be more negative than the + side.
  Non-polarized electrolytics are available in large values.
  Two polarized capacitors parallel do make a non-polarized capacitor, the Uf value is 2x..example; 2x .1uf paralleled = .2 uf

[bufftonz]

But with regards to the first circuit I showed up above, and the second modified one below it, which capacitor is ok to "not be electrolytic"?

[Barcode80]

well, basically it is okay for ANY cap to be ANY kind. the only reason large values are suggested to use electros is that once you get above around .47uF, the physical size of the cap for poly film/metal film/silver mica/etc. caps is just way too large to be practical in a stompbox. even a .1uF metal film cap is about 3/4 inch wide and fairly thick (.1 poly film is the smaller ones you are probably use to seeing. so the answer is, if you have a cap with the right value and voltage rating, put it in. it won't matter.

[mac]

I would replace it with a poly or ceramic cap. They sound better and do not age. But this is my personal taste, maybe an electrolytic sounds better to you.

mac

[Barcode80]

ceramic caps DEFINITELY age, and are the most prone to going microphonic. unless you are going for vintage sound, i suggest you don't use them on any value over 820pF or so.

[petemoore]

  But with regards to the first circuit I showed up above, and the second modified one below it, which capacitor is ok to "not be electrolytic"?
  Well...it shows no polarity of any kind, and looks like a circuit fragment.
 
Cap: observe that it will not see overvoltage.
  Choose your Uf value.
  Install.
  Polarized caps can't be reverse polarized, that means polarity must be observed and followed, the negative side of the cap [marked with - or > or ->->] needs to be more negative than the + side.
  Non-polarized electrolytics are available in large values.
  Two polarized capacitors parallel do make a non-polarized capacitor, the Uf value is 2x..example; 2x .1uf paralleled = .2 uf
  I think it's all there, can't think of anything to add...don't reverse polarize, don't overvoltage...that's it.

[Gus]

ceramic caps DEFINITELY age, and are the most prone to going microphonic. unless you are going for vintage sound, i suggest you don't use them on any value over 820pF or so.

They do?  I would like to see your data on this.

  Sometimes they fail and if they are microphoinc they start that way.  There are a few different types of ceramics



Also at lower voltages in effects the differences are less then you read about on the web.

That said you can find films at up to 10uf that are not too big for being a film.  Check CDE caps there are other companies.


Chris
google ASK etc capacitor types  and other things.  Look at the companies that make caps web site sometime there are good PDFs etc about caps.  Search here and old ampage and......

[5thumbs]

the only reason large values are suggested to use electros is that once you get above around .47uF, the physical size of the cap for poly film/metal film/silver mica/etc. caps is just way too large to be practical in a stompbox. even a .1uF metal film cap is about 3/4 inch wide and fairly thick (.1 poly film is the smaller ones you are probably use to seeing.

FWIW, AVX has a 63V boxed metal film 1.0uF cap that is much smaller than you may have seen in the past: http://www.mouser.com/Search/ProductDetail.aspx?qs=RlRj25DlwaCGQgVCCN0NrQ%3d%3d and http://avx.com/docs/catalogs/bf-bq.pdf.  They're about 7.5mm x 13mm x 7.5mm and fit in a lot of places 1.0uF electros will fit.  Their 0.47uF cap of the same series is slightly smaller, but works well for me as well.  I use both of these all the time as I replace small electros when modding pedals.

[mac]

I have a bunch of 6.8uf polys, 1 x 1.5 x 1.5 cm, 100V, 5%, unknown brand.
For example, 2 of them do a better job than a verifed 22uf electro in a FF.

I'm now experimenting with tants caps and a  poly in parallel about 1/10 the tant uf. Although some say that tants distors horrible. I guess it all depends on the ears and the pedal.

mac