Power Amp's NP capacitors and BP capacitors confuse ??

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Disabled Account
Joined 2014
Hi,

I am really confused about non-polar ELECTROLYTIC caps and bi-polar ELECTROLYTIC caps.

I am not asking about the difference between square type AC capacitors which use for motors and fans and normal electrolytic bi polar caps . ( I know those ac caps are non-polar. )

even when type on google '' what is the different between bi-polar and non-polar '' that gives the result of square type non-polar caps and electrolytic bi polar caps .

actually i need to know , is electrolytic non-polar and electrolytic bi-polar same ?
pls refer the attached pictures.

some says that we can easily make bp caps by soldering two normal electrolytic caps negatives together.

but in the market np electrostatics are available. but bp electrolytic caps are really difficult to find.

So if both same instead of making can i simply use non polar electrolytic caps instead of bi-polar electrolytic caps.

because my schematic says use 4.7/25v bi-polar caps.
 

Attachments

  • np.jpeg
    np.jpeg
    3.2 KB · Views: 237
  • bp.jpeg
    bp.jpeg
    5.1 KB · Views: 227
Last edited:
Disabled Account
Joined 2014
Thanks for the reply Mr.Dave and nigelwright7557 ,

appreciated your support. But need to ask onething,

is non polar and bi polar ( electrolytic ) same, then why the manufactures mention as ( NP ) and ( BP ) .
if same, they can simply mention either NP or BP on the body of cap.
 
Member
Joined 2010
Paid Member
I have read references here, incidentally from US members, that NP caps - typically only available in values suiting signal AC coupling - are differently constructed to the common Bipolar types used in crossover networks etc. I understand that there is a fundamental difference in that both electrodes are coated with an alumina deposit rather than just one so there are in effect 2 anode foils. This renders them inherently non-polarized rather than the pseudo depolarizing effect of assembling 2 polarized caps back to back. It may amount to the same thing electrically, but they aren't simply 2 caps.

Many Asian manufacturers label their bipolar caps BP or NP without distinction and I think we are accustomed to their freewheeling attitude to language and labelling subtleties in definitions, specifications, markings, quality issues and there is a need to be careful in the interpretation. I have no idea about any conditions applying to the use of allegedly true NP caps, their ratings etc. and I'd be happier if those with the experience would support this, or not, since reliable information is scarce.
 
In a practical sense, either one means there is no positive and negative end on the part. The distinction of the two might mean something at an engineering level or a philosophical level, but to a technician in the field, it means there is no overt polarity to concern with.

When your schematic says bipolar or nonpolar, it means that in that circuit, the voltage across the cap will not always be with one polarity, so you would not want to use a polarized electrolytic or tantalum type.
 
I have read references here, incidentally from US members, that NP caps - typically only available in values suiting signal AC coupling - are differently constructed to the common Bipolar types used in crossover networks etc. I understand that there is a fundamental difference in that both electrodes are coated with an alumina deposit rather than just one so there are in effect 2 anode foils.

Hi Ian
You are essentially correct about how non-polarized electrolytic capacitors are made, with a different foil anodization.
However the non polars electrolytics used in crossover networks are basically the same as any other, AFAIK.
There may be some "audiophile" flake who sells back-to-back electrolytics but I am not aware of any, yet.
So we probably should use "non-polar " and keep "bi-polar" for back-to-back or anti-parallel polar capacitors.
But manufacturers use the two terms arbitrarily I believe.

Best wishes
David
 
Non-polarised or bi-polar only describe a function - not a construction.

The brands and salesmen can invent other terms if they want to capitalise on doubt, uncertainty and confusion as the primary mechanism for differentiating their products to others in the market.
 
Dave Zan said:
So we probably should use "non-polar " and keep "bi-polar" for back-to-back or anti-parallel polar capacitors.
But manufacturers use the two terms arbitrarily I believe.
My understanding is that a bipolar cap has two anode foils. Two polar caps connected back to back is a poor man's approximation of this; useful in an emergency but not the same thing. So we should keep 'bipolar' for electrolytics which can be safely connected either way round, and 'nonpolar' for other caps (e.g. plastic film, ceramic) which do not care about polarisation. This is traditionally what they have both been called.

There is a difference between bipolar and nonpolar: bipolar caps need a voltage (and hence a little leakage current) to keep at least one of the oxide films healthy. Nonpolar caps do not need this as their dielectric is not subject to decay in the same way.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.