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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 |
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 |
Yeah, they're rolled up, but the contact is made across the ends,
generally, not just at one location in the roll. (That's why you should build that vector network analyzer...) But I'd avoid them: they can't take the heat. C0G ceramics and polyprops are both good. C0G ceramics are available up to 10nF or so even in SMT; polyprops down to 1nF at least and up to many uF. Cheers, Tom 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. |
Yeah, they're rolled up, but the contact is made across the ends,
generally, not just at one location in the roll. (That's why you should build that vector network analyzer...) But I'd avoid them: they can't take the heat. C0G ceramics and polyprops are both good. C0G ceramics are available up to 10nF or so even in SMT; polyprops down to 1nF at least and up to many uF. Cheers, Tom 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. |
On 17 Mar 2004 10:12:04 -0800, the renowned (Tom Bruhns)
wrote: Yeah, they're rolled up, but the contact is made across the ends, generally, not just at one location in the roll. (That's why you should build that vector network analyzer...) But I'd avoid them: they can't take the heat. C0G ceramics and polyprops are both good. C0G ceramics are available up to 10nF or so even in SMT; polyprops down to 1nF at least and up to many uF. Would you believe 100nF/25V C0G in 1206? Not insanely expensive either. http://www.murata.com/catalog/c02/es0011.pdf1206? (page 5) 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 |
On 17 Mar 2004 10:12:04 -0800, the renowned (Tom Bruhns)
wrote: Yeah, they're rolled up, but the contact is made across the ends, generally, not just at one location in the roll. (That's why you should build that vector network analyzer...) But I'd avoid them: they can't take the heat. C0G ceramics and polyprops are both good. C0G ceramics are available up to 10nF or so even in SMT; polyprops down to 1nF at least and up to many uF. Would you believe 100nF/25V C0G in 1206? Not insanely expensive either. http://www.murata.com/catalog/c02/es0011.pdf1206? (page 5) 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 |
In article , Paul Burridge
writes: 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? BIG difference between two types of rolled-foil style or "tubular" capacitors even at MF. For MF or even LF, use the low-inductance "extended foil" type; manufacturers will indicate that difference on datasheets, catalog listings. Extended-foil construction offsets the layering so that one foil overlaps the insulating film or paper at one end, the other foil overlapping the other end. When axial leads are attached, the foil overlaps is crimped down on the lead so that nearly all turns of the foil at one end contact the lead. Minimum inductance. Conventional old style of construction had the two foils neatly aligned with no foil protruding from the wider insulating layers. Axial leads were then clamped at only one end of the foil wrap end (usually the finish end) and the result had a fair amount of residual inductance in the remainder of the foil wrapping. A few makers introduced deliberately series-resonant bypass tubulars many years ago, intended for the ubiquitous 455 KHz IF amplifier stage bypassing. Broad series resonance but it worked (sort of). Rather a rare tubular now. Curiosity. Len Anderson retired (from regular hours) electronic engineer person |
In article , Paul Burridge
writes: 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? BIG difference between two types of rolled-foil style or "tubular" capacitors even at MF. For MF or even LF, use the low-inductance "extended foil" type; manufacturers will indicate that difference on datasheets, catalog listings. Extended-foil construction offsets the layering so that one foil overlaps the insulating film or paper at one end, the other foil overlapping the other end. When axial leads are attached, the foil overlaps is crimped down on the lead so that nearly all turns of the foil at one end contact the lead. Minimum inductance. Conventional old style of construction had the two foils neatly aligned with no foil protruding from the wider insulating layers. Axial leads were then clamped at only one end of the foil wrap end (usually the finish end) and the result had a fair amount of residual inductance in the remainder of the foil wrapping. A few makers introduced deliberately series-resonant bypass tubulars many years ago, intended for the ubiquitous 455 KHz IF amplifier stage bypassing. Broad series resonance but it worked (sort of). Rather a rare tubular now. Curiosity. Len Anderson retired (from regular hours) electronic engineer person |
"Spehro Pefhany" wrote in message ... | | Would you believe 100nF/25V C0G in 1206? Not insanely expensive | either. | | http://www.murata.com/catalog/c02/es0011.pdf1206? (page 5) | | 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 Gosh! Zero tempco decoupling for the digital folks. DNA |
"Spehro Pefhany" wrote in message ... | | Would you believe 100nF/25V C0G in 1206? Not insanely expensive | either. | | http://www.murata.com/catalog/c02/es0011.pdf1206? (page 5) | | 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 Gosh! Zero tempco decoupling for the digital folks. DNA |
On Wed, 17 Mar 2004 18:21:12 GMT, Spehro Pefhany
wrote: On 17 Mar 2004 10:12:04 -0800, the renowned (Tom Bruhns) wrote: Yeah, they're rolled up, but the contact is made across the ends, generally, not just at one location in the roll. (That's why you should build that vector network analyzer...) But I'd avoid them: they can't take the heat. C0G ceramics and polyprops are both good. C0G ceramics are available up to 10nF or so even in SMT; polyprops down to 1nF at least and up to many uF. Would you believe 100nF/25V C0G in 1206? Not insanely expensive either. It's almost as if they can defy the laws of physics these days.... Next thing you know: 100A FETs in the same package. :-| -- The BBC: Licensed at public expense to spread lies. |
On Wed, 17 Mar 2004 18:21:12 GMT, Spehro Pefhany
wrote: On 17 Mar 2004 10:12:04 -0800, the renowned (Tom Bruhns) wrote: Yeah, they're rolled up, but the contact is made across the ends, generally, not just at one location in the roll. (That's why you should build that vector network analyzer...) But I'd avoid them: they can't take the heat. C0G ceramics and polyprops are both good. C0G ceramics are available up to 10nF or so even in SMT; polyprops down to 1nF at least and up to many uF. Would you believe 100nF/25V C0G in 1206? Not insanely expensive either. It's almost as if they can defy the laws of physics these days.... Next thing you know: 100A FETs in the same package. :-| -- The BBC: Licensed at public expense to spread lies. |
On Wed, 17 Mar 2004 15:45:34 -0000, "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? Silly boy...... Sorry. I'll try not to ask such *stupid* questions again. -- The BBC: Licensed at public expense to spread lies. |
On Wed, 17 Mar 2004 15:45:34 -0000, "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? Silly boy...... Sorry. I'll try not to ask such *stupid* questions again. -- The BBC: Licensed at public expense to spread lies. |
Behold, Paul Burridge signalled from keyed 4-1000A filament:
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? Nope. That just indicates the "outside" foil - commonly goes to ground. -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Behold, Paul Burridge signalled from keyed 4-1000A filament:
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? Nope. That just indicates the "outside" foil - commonly goes to ground. -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
On Wed, 17 Mar 2004 23:01:13 -0000, the renowned "Emoneg"
wrote: Gosh! Zero tempco decoupling for the digital folks. DNA The Z5U parts pretty much magically disappear if you get them cold.. but X7R is good enuf. 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 |
On Wed, 17 Mar 2004 23:01:13 -0000, the renowned "Emoneg"
wrote: Gosh! Zero tempco decoupling for the digital folks. DNA The Z5U parts pretty much magically disappear if you get them cold.. but X7R is good enuf. 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 |
On Wed, 17 Mar 2004 12:03:06 +0000, Paul Burridge
wrote: 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. They're great for LC filters. If you choose your ferrite right, you can have a pretty stable filter over temperature. Problem is, not many people make these any more. For production, avoid them due to availability. If you're worried about inductance, that probably means that you're in the MHz region which means you can use NPO (COG) ceramic. Easier to get. Mark |
On Wed, 17 Mar 2004 12:03:06 +0000, Paul Burridge
wrote: 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. They're great for LC filters. If you choose your ferrite right, you can have a pretty stable filter over temperature. Problem is, not many people make these any more. For production, avoid them due to availability. If you're worried about inductance, that probably means that you're in the MHz region which means you can use NPO (COG) ceramic. Easier to get. Mark |
Behold, qrk signalled from keyed 4-1000A filament:
On Wed, 17 Mar 2004 12:03:06 +0000, Paul Burridge wrote: 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. They're great for LC filters. If you choose your ferrite right, you can have a pretty stable filter over temperature. Air-core my good man, air-core ;-) -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Behold, qrk signalled from keyed 4-1000A filament:
On Wed, 17 Mar 2004 12:03:06 +0000, Paul Burridge wrote: 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. They're great for LC filters. If you choose your ferrite right, you can have a pretty stable filter over temperature. Air-core my good man, air-core ;-) -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
"Paul Burridge" wrote in message
... On Wed, 17 Mar 2004 15:45:34 -0000, "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? Silly boy...... Sorry. I'll try not to ask such *stupid* questions again. no stupid questions, unless you ignored the answers last time..... remember, things you know are easy. Its the things you dont know that are hard. |
"Paul Burridge" wrote in message
... On Wed, 17 Mar 2004 15:45:34 -0000, "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? Silly boy...... Sorry. I'll try not to ask such *stupid* questions again. no stupid questions, unless you ignored the answers last time..... remember, things you know are easy. Its the things you dont know that are hard. |
On Thu, 18 Mar 2004 05:27:09 GMT, Gregg wrote:
Behold, qrk signalled from keyed 4-1000A filament: On Wed, 17 Mar 2004 12:03:06 +0000, Paul Burridge wrote: 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. They're great for LC filters. If you choose your ferrite right, you can have a pretty stable filter over temperature. Air-core my good man, air-core ;-) Try air-core with 500+ uH. Then pack em in to a small area. That's what I get for being a low-freq weenie. |
On Thu, 18 Mar 2004 05:27:09 GMT, Gregg wrote:
Behold, qrk signalled from keyed 4-1000A filament: On Wed, 17 Mar 2004 12:03:06 +0000, Paul Burridge wrote: 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. They're great for LC filters. If you choose your ferrite right, you can have a pretty stable filter over temperature. Air-core my good man, air-core ;-) Try air-core with 500+ uH. Then pack em in to a small area. That's what I get for being a low-freq weenie. |
Behold, qrk signalled from keyed 4-1000A filament:
Air-core my good man, air-core ;-) Try air-core with 500+ uH. Then pack em in to a small area. That's what I get for being a low-freq weenie. Ah! I too am a LowFER - Made a 6Hy coil in about 4 sq. inches on my winding jig. No current capacity but a great 20-76KHz preselect for the vacuum tube RX :-) -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Behold, qrk signalled from keyed 4-1000A filament:
Air-core my good man, air-core ;-) Try air-core with 500+ uH. Then pack em in to a small area. That's what I get for being a low-freq weenie. Ah! I too am a LowFER - Made a 6Hy coil in about 4 sq. inches on my winding jig. No current capacity but a great 20-76KHz preselect for the vacuum tube RX :-) -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
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