Tantalum markings?

Discussion in 'General Electronics Chat' started by ctwistedpair, May 14, 2013.

  1. ctwistedpair

    Thread Starter New Member

    Jan 14, 2013
    25
    2
    I have a circuit that requires a tantalum cap. I have a bunch of old epoxy tantalums but I cant decipher the markings. I cant seem to find any websites that document tantalum cap codes. One of my caps says 2.2-6 m. Any idea what this means?

    Thanks in advance for your help.
    Carl
     
  2. #12

    Expert

    Nov 30, 2010
    16,330
    6,818
    2.2 microfarads 6 volts maximum
     
    Rbeckett and ctwistedpair like this.
  3. ctwistedpair

    Thread Starter New Member

    Jan 14, 2013
    25
    2
    Can I use electrolytics in place of tantalum? If so, is it an equal exchange?
    Thanks again!
     
  4. #12

    Expert

    Nov 30, 2010
    16,330
    6,818
    Usually. Tantalums are a little bit better in some situations.
     
  5. Rbeckett

    Member

    Sep 3, 2010
    205
    32
    #12,
    Could you expound on the criteria you use when deciding or choosing between Tantalum, Polyester, and electrolytics please. I know they each have a different base material and some have better adherence to closer tolerances, but I am at a loss on how to select the appropriate base material between all of the choices. Is it based on use, possible noise or capacity. Any kind of primer or guidance would be very illuminating and add to the thread considerably.

    Wheelchair Bob
     
  6. #12

    Expert

    Nov 30, 2010
    16,330
    6,818
    I am not an expert, but I'm not a beginner, so here goes:

    Aluminum electrolytics are for a lot of capacitance at a voltage a Tantalum can't do or a price you can't afford. I've paid as high as $10 each for 100uf/10V tantalums when the circuit needed them, but I would much rather pay 9 cents for aluminum capacitors...unless I'm making something to last forever. Tantalum doesn't leak, so I made guitar effects that didn't have any components that were guaranteed to die in a decade or two. On the other hand, I have some "Computer Grade" aluminum capacitors from 1970 that still work on my test bench. Big cans with bolts for terminals. Somebody threw then in the trash because they had been in use for some amount of hours. It IS possible to buy good aluminum caps, but they aren't 6 for a dollar and they won't fit in a "stomp box" (guitar effects).

    Poly-whatever caps are for audio coupling. They have the lowest dissipation factor of all capacitors. That means they don't absorb energy into the dielectric as much as any other capacitor. The audio-phools believe this changes the sound, and they are my customers, so they get what they want. They also believe that if a fly landed on the deck of an aircraft carrier, it would change the way you hear the sound of the ships' engine. I don't bother to argue with religious people.

    Ceramic capacitors are small, cheap, and do high frequencies better than aluminum caps. They go to rather high voltages, too.

    You can spend a day reading spec sheets on capacitors. I know, because I did. That's how I finally nailed down why audio people want Orange Drops.

    Edit: I guess I should say that capacitors are generally better than the spec sheet says. According to the "guaranteed" leakage, you can't get 5 minutes on a 555 timer with an aluminum electrolytic capacitor. The leakage will exceed the current allowed by the timing resistor. In reality, you can. You might have to pick a good one out of your junk box, but you can usually find a low leakage aluminum capacitor.
     
    Last edited: May 15, 2013
    ctwistedpair likes this.
  7. ctwistedpair

    Thread Starter New Member

    Jan 14, 2013
    25
    2
    Are Electrolytic caps a direct swap for a tantalum, or is there some conversion factor?
     
  8. #12

    Expert

    Nov 30, 2010
    16,330
    6,818
    Based on you not telling me what kind of circuit this is in, a microfarad is a microfarad. A 2.2 uf tantalum will act the same as a 2.2 uf aluminum capacitor until you get to strange effects like a frequency limit in the megaherts range.
     
  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,061
    3,826
    Note that polarity markings on a tantalum cap are USUALLY on the positive terminal.

    Polarity markings for Aluminum electrolytic caps are USUALLY (almost always) on the negative side.
     
Loading...