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Corcom (or other) AC line filters — Parallax Forums

Corcom (or other) AC line filters

xanatosxanatos Posts: 1,120
edited 2011-12-09 13:59 in General Discussion
I've always been a fan of Corcom Line filters - partly because I had a seemingly unending supply of them, for free, from surplus equipment. I never had to buy them before... until now. But now when I search Digikey, Mouser or Jameco, it seems that the ones I want to use are not available, and I suspect it is because I am not understanding the criteria for which I am searching. While I am using the Corcoms with regular 120VAC, must I specify them as 120 VAC, or can I go with a unit specified at 250 VAC or above? Those units LOOK like the ones I have been using... I just need to know if when using Corcom line filters, if it is fine/normal practice to use a unit rated for 250vac+ on a system that will be using regular 120 vac line voltage.

Also - if anyone has a better suggestion for line filters than Corcom, I'm open to hearing about them. I just got used to using Corcoms because I had so many of them that I removed from scrapped equipmnent.

THANKS!

Dave

Comments

  • $WMc%$WMc% Posts: 1,884
    edited 2011-12-08 19:15
    Theres probably some "muddywater" about peak to peak and RMS voltage some where in the spec sheet.
    '
    This helps to make reading the spec sheet about as clear as mud.
  • Mike GreenMike Green Posts: 23,101
    edited 2011-12-08 19:16
    These days with the widespread use of switching power supplies, most supplies are designed for operation from about 90VAC to 240VAC, so it makes sense that most line filters would be designed for use up to 250VAC. The main reason for using a line filter designed for 120VAC at the design voltage is size and weight. The extra insulation and higher rating capacitors may be a little bigger and a little heavier. I doubt there's much difference in practice.
  • davejamesdavejames Posts: 4,047
    edited 2011-12-08 19:58
    Hi Dave,

    http://www.cor.com/pdf/EC.pdf

    There really isn't anything obvious concerning 120VAC and 250VAC. The only item was leakage current.

    I'm gonna guess you'd be ok with a 250VAC rated unit in a 120VAC application. It's really about the current anyway - for the chokes to work properly, that is.

    DJ
  • xanatosxanatos Posts: 1,120
    edited 2011-12-08 20:35
    Cool, thanks. The 250vac units are cheaper, too! I thought the 250v units would be fine, but I wanted to check with folks with a more experienced view on these.. Thanks for your input guys!

    Dave
  • RDL2004RDL2004 Posts: 2,554
    edited 2011-12-09 08:16
    Just a note about something to watch out for when searching on parameters. I've seen this happen a Mouser and a few other places.

    If you specify a certain parameter and an item doesn't have that particular parameter in it's database entry, it won't show up in the search results. For instance, if you're searching for a certain color of LED in 3mm, an LED with it's size specified as T-1 (or no size at all) probably won't appear in search results. In your case, 120 VAC may exclude items rated 90-240 VAC.
  • xanatosxanatos Posts: 1,120
    edited 2011-12-09 08:32
    Thanks, Rick. I have found those parametric searches to be something of a pain. I usually try to select multiple options that span the entire range, but even still sometimes something gets hidden that I think should still show up.

    I wish they had a boolean search like the old Altavista search engine had, where you could specify AND, OR, AND NOT, and my favorite, NEAR... NEAR was awesome!

    Dave
  • ercoerco Posts: 20,259
    edited 2011-12-09 08:58
    Corcom AC line filters: Maybe

    Corvair AC oil filters: Definitely
    acfilter.JPG
    833 x 557 - 77K
  • xanatosxanatos Posts: 1,120
    edited 2011-12-09 09:08
    erco wrote: »
    Corcom AC line filters: Maybe

    Corvair AC oil filters: Definitely

    What??? :-)
  • hover1hover1 Posts: 1,929
    edited 2011-12-09 09:20
    erco wrote: »
    Corcom AC line filters: Maybe

    Corvair AC oil filters: Definitely

    Like!
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2011-12-09 10:17
    Corcoms are excellent for solidstate audio, in particular op amp based preamps.

    From what I can sort out, many of the modern wall warts are just fine for microcontrollers and don't require further transident trapping unless you have local problems with lightning.
  • ercoerco Posts: 20,259
    edited 2011-12-09 10:31
    xanatos wrote: »
    What??? :-)

    BTW xanatos: You live near the world's largest supply of Corvair parts in Shelburne Falls, MA. I'm so jealous!

    http://www.corvair.com/user-cgi/main
  • xanatosxanatos Posts: 1,120
    edited 2011-12-09 13:59
    Yup... Shelburne falls us just about another half hour from where I am right now in Northampton. Beautiful place... never knew they were famous for Corvair parts!

    And LoopeyB... So far, the ONLY failures I've ever had on my production designs have been due to voltage spikes due primarily to lightening (upstate NY). So I have become a stickler for filters on everything.

    A story related to this... When I was about 14, I built my first speech generator using an SPO-256. It was working nicely until I made a mod to make a few phoneme combinations directly addressable by using a dip switch. But I made a critical error by not isolating it from my air compressor pump motor. I powered it up and when the motor started up, my poor SPO-256 actually spoke of its own accord as it was dying. It actually said: "ow ow ow ow ow ow ow..." and fell silent forever. I actually felt sorry for it. I have always tried to protect my circuitry to a ridiculous degree ever since then! :-)
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