Hi, I am recently reading a schematics for a parametric filter for
audio application, and in service manual they have listed the type and
value of all the capacitors they uses. They have POLY ( for polyester
), ELEC ( for electrolytic ), and a mystery one called PLAQ. I wonder
if anyone can help me identify what type of capacitor that stands for.

These PLAQ capacitors are all in the range of a few hundred pF to a
couple of nF. Most of them are placed across the 'OUT' and the '-'
termainal of opamps ( together with other feedback components) .
Looking at the circuit board, they are greyish/light brownlish in
color and look very much like ceremic capacitors in size and shape
(they are all dipped with a color band on top).

Thanks.

you know what to remove to reply to !

Al wrote:

Hi, I am recently reading a schematics for a parametric filter for
audio application, and in service manual they have listed the type and
value of all the capacitors they uses. They have POLY ( for polyester
), ELEC ( for electrolytic ), and a mystery one called PLAQ. I wonder
if anyone can help me identify what type of capacitor that stands for.

These PLAQ capacitors are all in the range of a few hundred pF to a
couple of nF. Most of them are placed across the 'OUT' and the '-'
termainal of opamps ( together with other feedback components) .
Looking at the circuit board, they are greyish/light brownlish in
color and look very much like ceremic capacitors in size and shape
(they are all dipped with a color band on top).

Certainly sounds like plate ceramics to me. The 'PLA' bit may mean 'plate'
in this manufacturers' thinking. Maybe the 'Q' refers to the dielectric ?
As in Quality perhaps ? In the application and capacitance size you
mention, that would mean a 'low-K' dielectric that has generally superior
characteristics such as tempco to other dielectrics often used in ceramic
caps of larger value.


Graham

"Al"

Hi, I am recently reading a schematics for a parametric filter for
audio application, and in service manual they have listed the type and
value of all the capacitors they uses. They have POLY ( for polyester
), ELEC ( for electrolytic ), and a mystery one called PLAQ. I wonder
if anyone can help me identify what type of capacitor that stands for.



** Is this schematic originally from a non English speaking country ???

Wanna bet "PLAQ" is short for PLAQUE - a mistranslation of the word
"ceramic".

As in the phrase "ceramic plaque".




......... Phil

Thanks everyone, I think you are right. Someone in the newsgroup
gave me a website to a ceremic plate capacitor manufacture, and those
PLAQ caps I have look exactly like the ones they have on the web, down
to the color band on top. Turns out the color band designate the
dielectric material, like NP0, X5S etc.

Thanks everyone, I think you are right. Someone in the newsgroup
gave me a website to a ceremic plate capacitor manufacture, and those
PLAQ caps I have look exactly like the ones they have on the web, down
to the color band on top. Turns out the color band designate the
dielectric material, like NP0, X5S etc.