[sdiy] Polarized VS non-polarized electrolytic caps

[ganesha]

Thanks for the detailed explanation, Harry.

In the past I've used electrolytic caps marked B.P (Bi polar ??) and they are indeed a lot bigger in size. But the ones I bought now are marked N.P. (Non polar ??) and are quite small, they seem to have the same size as regular electrolytic caps. Is there a difference between B.P and N.P. ?

Thanks,
K.



----- Original Message -----
From: Harry Bissell <harrybissell at wowway.com>
To: ganesha <goaqihai at yahoo.co.uk>
Cc: synth-diy at dropmix.xs4all.nl
Sent: Saturday, 21 January 2012, 11:46
Subject: Re: [sdiy] Polarized VS non-polarized electrolytic caps

You can use a non-polar electrolytic in a polarized application, no problem.

The non-polar cap will be physically larger than its polarized counterpart.

In essence, the non-polar cap is two capacitors in series with the plus sides facing out (the leads)

To get the same value, each section must be two times the capacitance... so a 1uF non-polar will be,made of two, 2uF caps in series.

Its possible to use two polar electrolytics in series, but I don't recommend that especially in higher ripple current applications
like speaker crossovers etc...

I use non-polar electrolytics for almost all coupling capacitors bigger than maybe .47uF (smaller values can easily be film or ceramic
caps).

Some people use two polar electrolytic caps in series, with the center point (both negative terminals)biased through a high value
resistor to the negative supply rail to prevent the dielectric from degrading with time. I don't know how this is accomplished in the
commercial non-polar caps, but I have never had a problem with them going bad.

tmi ?

H^) harry


----- Original Message -----
From: ganesha <goaqihai at yahoo.co.uk>
To: synth-diy at dropmix.xs4all.nl
Sent: Sat, 21 Jan 2012 05:16:29 -0500 (EST)
Subject: [sdiy] Polarized VS non-polarized electrolytic caps

Hi,
For a schematic I need  1µF polarized electrolytic caps, but I accidentally bought  1µF non-polarized electrolytic caps, so with no + or - indication on them, just N.P.
Can I use these anyway or is there a fundamental difference between polarized and non-polarized, no matter what their purpose is in the schematic?

Thanks,
K.

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Harry Bissell & Nora Abdullah 4eva