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Simple Newbie Capacitor Question

Discussion in 'Beginner Electronics' started by Bob Grimm, Nov 5, 2003.

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  1. Bob Grimm

    Bob Grimm Guest

    Hello,

    I'm just getting my feet wet in electronics and have started working
    thru Myke Predko's Digital Electronics Guidebook.

    Anyhow the projects specify using 0.1uF 16V Tantalum
    capacitors.

    Neither my local Radio Shack or DigiKey (where I prefer
    to purchase my parts) have anything less than 1uF Caps.

    Question is can I use 1 uF Caps in place of 0.1uF or am
    I competely wrong.

    I understand derating the voltage of the capacitors but I'm
    not sure if the capacitance HAS to be specific to the project.

    Thanks,
    BG
     
  2. scada

    scada Guest

    You did not try hard enough.And no, a 1 µf Cap is not the same as a .1µf
    cap! Go to www.digikey.com search for capacitor, then Tantalum. Put in the
    value (you can use a higher voltage, if physical space allows). One hit I
    got, part# 399-1348-ND (0.1 µf / 35V) which is one of many!
     
  3. Bob Grimm

    Bob Grimm Guest

    Most of the projects are 12v and so the specification was to
    deregulate the voltage to 16v Caps.

    I did indeed see the 35v caps in the list but was hoping to stick
    to what was recommended. (16 volt).

    I know there is no harm done in using a MUCH greater than required
    voltage capacitor. My question was regarding the capacitance.

    Thanks,
    BG
     
  4. andrew

    andrew Guest

    Bob,

    Use 0.1uF 'box polyester' or 'disc ceramic' . The parts will be used as
    decoupling caps probably 1 per chip package in the circuit. you can also use
    down to 0.01uF for this. Value is not too critical for decoupling in 'home '
    projects.

    Andrew.
     
  5. Spudley

    Spudley Guest

    I would use a standard 0.1 uF ceramic or poly capacitor instead, as
    long as it's voltage equalled or exceeded the spec called for in the
    schematic.
    0.1uF caps are normally used for bypass purposes "Noise reduction"
    within circuits, Tantalums are polarised, and are lower voltage.
     
  6. miketinte

    miketinte Guest

    It depends on the application. Changing the capacitor value will
    change the timing constant and cutoff frequencies, as well as DC
    behavior of the circuit. Without knowing what exactly you're using the
    cap for, it's hard to say WHAT effect the differenct capacitance will
    have on the desired outcome, but it definitely will affect it. Go with
    the specified capacitance, there's usually a reason it was chosen.
     
  7. JeffM

    JeffM Guest

    the projects specify using 0.1uF 16V Tantalum capacitors.
    I'm with Spudley. Ceramics are cheap (watch the tolerances
    --tho if tantalum was originally specified, it's probably not an issue).

    Films are a little more expensive but spec'd tighter.

    The only reason I can imagine for calling out a 0.1uF tantalum
    would be to pack the cap into the smallest possible volume.


    Using caps with a higher voltage rating
    is akin to putting a 429 into a Ford when the speed limit is 35
    --a 2L 4-banger will do the trick.
    At idle you just use more gas (cap-->wasted volume, more leakage).
     
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