Polystyrene capacitors for filter networks?
 

Hi,

They look worryingly inductive on visual inspection (there are metal
foils rolled up in thar by the look of it.) And yet the CPC catalogue
says that their properties make them ideal for use in filters. Has
anyone any remarks (favourable or otherwise) to make about the use of
this type of cap in filter apps?

p.
--

The BBC: Licensed at public expense to spread lies.

Hi Paul!

There are non-inductively wound ones specifically for the purpose. The
mfr. specs should show an ESR curve - the non-inductive ones are pretty
flat to their SRF.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

Hi Paul!

There are non-inductively wound ones specifically for the purpose. The
mfr. specs should show an ESR curve - the non-inductive ones are pretty
flat to their SRF.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

"Paul Burridge" wrote in message
...
Hi,

They look worryingly inductive on visual inspection (there are metal
foils rolled up in thar by the look of it.) And yet the CPC catalogue
says that their properties make them ideal for use in filters. Has
anyone any remarks (favourable or otherwise) to make about the use of
this type of cap in filter apps?

They are OK for LF filters, the inductance won't make any appreciable
difference and they are available with 1% tolerance. They are getting
difficult to find. They are also useful for RF oscillators.

Leon

"Paul Burridge" wrote in message
...
Hi,

They look worryingly inductive on visual inspection (there are metal
foils rolled up in thar by the look of it.) And yet the CPC catalogue
says that their properties make them ideal for use in filters. Has
anyone any remarks (favourable or otherwise) to make about the use of
this type of cap in filter apps?

They are OK for LF filters, the inductance won't make any appreciable
difference and they are available with 1% tolerance. They are getting
difficult to find. They are also useful for RF oscillators.

Leon

"Paul Burridge" wrote in message
...
| Hi,
|
| They look worryingly inductive on visual inspection (there are metal
| foils rolled up in thar by the look of it.) And yet the CPC catalogue
| says that their properties make them ideal for use in filters. Has
| anyone any remarks (favourable or otherwise) to make about the use of
| this type of cap in filter apps?
|
| p.
| --
|
| The BBC: Licensed at public expense to spread lies.

Silly boy...... Go and find out about construction methods. The
metallisation is offset so the end terminations parallel the internal
layers.

DNA

"Paul Burridge" wrote in message
...
| Hi,
|
| They look worryingly inductive on visual inspection (there are metal
| foils rolled up in thar by the look of it.) And yet the CPC catalogue
| says that their properties make them ideal for use in filters. Has
| anyone any remarks (favourable or otherwise) to make about the use of
| this type of cap in filter apps?
|
| p.
| --
|
| The BBC: Licensed at public expense to spread lies.

Silly boy...... Go and find out about construction methods. The
metallisation is offset so the end terminations parallel the internal
layers.

DNA

On Wed, 17 Mar 2004 12:30:56 GMT, Gregg wrote:

Hi Paul!

There are non-inductively wound ones specifically for the purpose. The
mfr. specs should show an ESR curve - the non-inductive ones are pretty
flat to their SRF.

I notice some of them come with one end tinted red (or sometimes
black). Does this indicate the non inductively-wound type?

--

The BBC: Licensed at public expense to spread lies.

On Wed, 17 Mar 2004 12:30:56 GMT, Gregg wrote:

Hi Paul!

There are non-inductively wound ones specifically for the purpose. The
mfr. specs should show an ESR curve - the non-inductive ones are pretty
flat to their SRF.

I notice some of them come with one end tinted red (or sometimes
black). Does this indicate the non inductively-wound type?

--

The BBC: Licensed at public expense to spread lies.

On Wed, 17 Mar 2004 15:45:34 -0000, the renowned "Emoneg"
wrote:


"Paul Burridge" wrote in message
.. .
| Hi,
|
| They look worryingly inductive on visual inspection (there are metal
| foils rolled up in thar by the look of it.) And yet the CPC catalogue
| says that their properties make them ideal for use in filters. Has
| anyone any remarks (favourable or otherwise) to make about the use of
| this type of cap in filter apps?
|
| p.
| --
|
| The BBC: Licensed at public expense to spread lies.

Silly boy...... Go and find out about construction methods. The
metallisation is offset so the end terminations parallel the internal
layers.

DNA

Yup. Take two sheets of letter-size (okay, A4) paper and lay one on
top of the other but the top one to the right by 1/2". These are like
the plates of your capacitor. Now roll them up from the bottom to the
top into a tight roll. Imagine you connect to all the right end (in
parallel) by dipping it in some conductive goop, and call that lead A.
Do the same to the left, and call it lead B. The coiled construction
adds no inductance.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com