Ad Widget

Collapse

Announcement

Collapse
No announcement yet.

Caps In Series

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
  • #1

    Caps In Series

    Okay Everyone,

    I feel like a dunder-head asking this, but I'll do it anyway.

    I know we can stack electrolytic caps in series to boost voltage handling & that the values add like resistors in series. Can I also add non-polaeized caps in series to boost voltage handling?

    This is for testing an amp tweak (conjunctive filter) that would call for a 1000V cap, which I don't have. I just wanna test the mod before I order some 1000V caps, because I'm pretty sure I'd hafta find a new vendor for them & that's kinda a P.I.T.A.

    Thanks!

    Justin
    "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -
    Tags: None
  • #2
    Oops, the values (capacitances) get smaller, as in parallel resistors.

    As for the other question, I think you could put two in series if you had to. 1kV and 2kV ceramic caps are very common and any supplier should have them. Maybe even Radio Shack.

    Comment

    • #3
      Series caps of all types will increase voltage rating. I'm not sure how much balancing with resistors should be observed in this case though. But...

      FWIW my experience, and apparently that of the good Dr. Z is that it takes a pretty burly capacitor to handle shunt filter service across tube amp OT primaries. Voltage spikes can be stupid high in this circuit. Like 2x+HV. I didn't know better when I installed a 600V 715p orange drop type in an amp with 370Vp. It lasted a little while. Maybe three weeks. Then the amp started to sound "off" and I started noticing "that smell". Not knowing what the problem was I opened up the amp. With no visible signs yet present I started wailing through it with the chassis on the bench. The problem continued to worsen. What was happening was that the cap was repeatedly shorting and healing until it wasn't really a capacitor at all anymore. That's when I noticed the 10W wire wound resistor browning it's color bands. You gotta have a high voltage rated resistor for this circuit also in the event that the cap shorts. Ideally there's no HV across the resistor I suppose and if the cap fails then you'll be fixing it anyway. But I went with an 11W "high energy" resistor rated for some crazy high voltage and a 2kV cap designed for snubber service. No more problems. I mentioned the doctor because he had a run of amps that were notorious for burning up the "conjunctive filter". This is a guy that would know better and the parts he believed would be up to the task weren't. My point is, overshoot with respect to ratings here. And while I don't see too much harm in using what you have on hand for testing you might just prepare yourself for tossing them for more appropriately selected parts you're going to buy later.

      JM2C
      "Take two placebos, works twice as well." Enzo

      "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

      "If you're not interested in opinions and the experience of others, why even start a thread?
      You can't just expect consent." Helmholtz
      • Likes 1

      Comment

      • #4
        that the values add like resistors in series
        When wiring things in series, their impedances add. As the impedance of capacitors is inversely proportional to their capacitance, we get 1/Cser = 1/C1 + 1/C2.
        So for C1 = C2 = C it follows 1/Cser = 2/C or Cser = C/2.
        - Own Opinions Only -

        Comment

        • #5
          Originally posted by Helmholtz View Post
          When wiring things in series, their impedances add. As the impedance of capacitors is inversely proportional to their capacitance, we get 1/Cser = 1/C1 + 1/C2.
          So for C1 = C2 = C it follows 1/Cser = 2/C or Cser = C/2.
          Right on. So, to put it in laymans terms, when you use two capacitors in series the impedance is additive, the capacitance as a value statement is divided. Two 2n caps in series will have a value of 1n. Which has twice the impedance as a 2n cap. And this is the case whether caps are used singular or in series. A 1n "capacitance" has twice the impedance of a 2n "capacitance".

          I hope I didn't just make it more confusing
          "Take two placebos, works twice as well." Enzo

          "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

          "If you're not interested in opinions and the experience of others, why even start a thread?
          You can't just expect consent." Helmholtz

          Comment

          • #6
            Originally posted by Bloomfield View Post
            Oops, the values (capacitances) get smaller, as in parallel resistors.

            As for the other question, I think you could put two in series if you had to. 1kV and 2kV ceramic caps are very common and any supplier should have them. Maybe even Radio Shack.
            Geez, yeah, I knew that first part... It was in my head. I'll leave my error up for future readers, but I did alreasy know that... (Kicks own ass)

            While those high-voltage ceramic caps might be common, I'm not a builder or shop & don't recall either tubedepot or AES having them. And Radio Shack is now defunct-kaput-byebye. And the last time I went there asking for a high-voltage cap they looked at me like I had three heads. And that was only for a 500V electrolytic. "What are you doing that needs THAT?" "Fixing a tube amp." "A what?" "Nevermind..."

            Jusrin
            "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
            "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
            "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

            Comment

            • #7
              Hey All,

              Thanks for the replies. Yeah, colossal stupid on my part, I know that caps in series add like resistors in parallel. It was in my brain but just didn't translate. I've got two .0033s in series in it right now cuz I wanted something between .002 & .001.

              As for the I-word, I still don't get it.

              Thanks forthe relay of experience, Chuck. This is just for a short-term check, to see if it'll do what I'm looking for. If the test run works I'll get proper parts. But I was basically gonna use a couple 630V Mallorys in series cuz B+ is about 475V, ~520 unloaded. Maybe I'll use 3, don't know yet.

              Anyhoo, good to know the "law" still applies.

              Justin
              "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
              "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
              "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

              Comment

              • #8
                Originally posted by Justin Thomas View Post
                Geez, yeah, I knew that first part... It was in my head. I'll leave my error up for future readers, but I did alreasy know that... (Kicks own ass)
                I took it that you meant 'voltage values' but should have used the word 'rating' instead of value.
                Originally posted by Enzo
                I have a sign in my shop that says, "Never think up reasons not to check something."


                ​

                Comment

                • #9
                  Well, I guess if you're getting zapped, the value matters more thsn the rating. Because it's the voltage on the INSIDE that kills, not the voltage that's outside looking forca home that bites you.

                  Justin
                  "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                  "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                  "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

                  Comment

                  Previous template Next
                  Working...
                  X