Confused about this part

Discussion in 'General Electronics Chat' started by cat3rn, Mar 17, 2009.

  1. cat3rn

    Thread Starter Active Member

    Jun 3, 2008
    117
    0
    I have a part that I need to replace but unsure of what it is. I think it is a cap but hard to find this style.

    Pic attached

    Its 5.6uF 100V
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Well, 5.6 uF is an odd value. The 100 volt part is easy enough, though. What does it do?

    The electrolytics in my catalogs mostly jump in value from 4.7 to 6.8 uF.
     
  3. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    It is not a polarized electrolytic. It is a non-polar film capacitor that come in all 5% values.

    Some people call them Mylar capacitors. I call them metalized plastic film capacitors. In the Orient they are called a "green cap".
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    And now I see the axial leads. Panasonic makes one - Digi-Key part #E1565 @ $3.23.
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
  7. cat3rn

    Thread Starter Active Member

    Jun 3, 2008
    117
    0
    It is part of a crossover for an Alpine F1 series car audio speaker system for the mids and highs. Just wondering if it is a cap because it is so large. Might be a couple of years old.
     
  8. cat3rn

    Thread Starter Active Member

    Jun 3, 2008
    117
    0
    I am trying to figure out what type and size of air coil to use. One measures 0.4ohm and the other is 0.5ohm and unsure of which one removes the low bass below 700Hz and the other below 3800Hz to keep the mid and tweeter from blowing.
     
  9. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The coils have inductance that attenuates high frequencies when they are in series with a woofer or a midrange speaker. The inductance can be calculated if you know the frequency and the impedance of the woofer at that frequency.

    I think the woofer has the left inductor in series and the 22uF capacitor in parallel.
    And the tweeter has the 12uf capacitor in series then the coil to ground then the 5.6uF capacitor in series.
    I like the light bulb current-limiter on the right side for the tweeter.
    You want the resistance to be as low as is possible so the woofer gets full power.
     
  10. cat3rn

    Thread Starter Active Member

    Jun 3, 2008
    117
    0
    I am planning to build these crossovers myself. The speakers are Alpine SPX-137R Manual here
    http://vault.alpine-usa.com/products/documents/OM_SPX-137R.PDF
    I also have the 177r in the rear deck.

    What part would you suggest buying from Mouser or Digikey?
     
  11. cat3rn

    Thread Starter Active Member

    Jun 3, 2008
    117
    0
    Also does anyone know where to get the gold plated solid metal fuse jumpers?
     
  12. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    From Alpine.

    If those are 1 1/4" X 1/4" clips, we used to have a collection of sawed-off potentiometer shafts for blow-proof fuses. All it's gotta do is conduct.
     
  13. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Are you building another circuit like the one shown in your attachment, using the Alpine crossover for a reference?

    I'm confused by "size and type of air coil to use", when the circuit looks complete.

    --ETA: Thread was in cache and didn't refresh. The value needs to be calculated for the coils, in uH/mH. The DC resistance (0.5 Ohm/0.4 Ohm) is only relative to the Q of the inductor, and not the actual value.
     
  14. cat3rn

    Thread Starter Active Member

    Jun 3, 2008
    117
    0
    I did not think of that I have a few laying around. Thanks

    Yes I am trying to duplicate that circuit. How do I find the Q of the coil? I could then put that info on the forum to help with the diagnosis of the circuit.
     
  15. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The inductance of the air coils could be replicated fairly closely, if the inside diameter, inside length, and flange diameter of the plastic bobbins were known, along with the gauge of the wire wrapped around it.
     
  16. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The 5.25" speakers are too small to be woofers and have low sensitivity.
    The 6.5" woofer also has low sensitivity.

    The crossovers in the manual have the inductances of the coils.
    I doubt if you can buy the coils.

    Use a power amplifier for each speaker and make an active crossover with opamps (no coils).
     
  17. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Hmm, I don't think that standard fuses are 1/4" in diameter. Trying to cram a standard 1/4" pot shaft into the fuseholder/jumper would probably damage them. Seems to me that AWG 4 solid copper wire might be a close match, but I don't know where my spouse hid my digital calipers at the moment, so I can't check. :rolleyes:

    Many older pot shafts were made of brass. They would have 4.8 times the resistance of copper. Newer pot shafts seem to be made from aluminum; they're about 1.55 times the resistance of copper, but have a nagging tendency to return to their natural state (bauxite, a white powder) that does not conduct electricity well at all.

    The jumpers were gold plated to eliminate the corrosion problem. Internally, they were most probably solid copper.
     
  18. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    OK, so Audioguru says the inductance of the coils is in the manual; so that unknown is solved.

    Next, the AWG size of the wire used in the coils needs to be determined. An inexpensive digital caliper obtained from someplace like Harbor Freight Tools would suffice for the measurement. After that, it's selecting an appropriate bobbin, obtaining the wire, and winding the turns on.
     
  19. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Using the "jumpers"/fuses currently set, These values should be close (10%) to the corner frequencies, I am guessing the inductor on the woofer side is a bit smaller to have resistance under 1Ω, or heavier wire than I'm estimating from pictures.:

    Scratch these... Had 150uH and 1.5mH, using 20 ga wire (0.8mm). Manual uses 1mm wire - 18ga.
    Proper dimensions soon.

    Finally, the 1.5Ω/10W Resistor should be mounted above the board about 1/2" for air circulation, the bottom side of the board is discolored due to that resistor overheating.

    --ETA: I wish I would have refreshed to see inductor values were known before I did all those calculations. :( Interested to see if I'm even in the same realm, or missed by several octaves.... or a m in place of a 'u'....



    -- Manual shows 320uH and 3 inductors, valued from 100 to 320uH. 1mm wire.Inductors: Air Core; 1mm wire (0.2W DCR), 0.7mm (0.3-0.5W DCR)
     
    Last edited: Mar 19, 2009
  20. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Correct instructions for inductors from manual (value and wire gauge)

    Identical cores, Look like what is shown in your photo: 3/4" inside diameter, 1/2" tall, 18ga Enameled Wire:

    0.10mH - 72 turns, 16.5 ft wire, Est Resistance 0.12 Ohms

    0.18mH - 95 turns, 23.5 ft wire, Est Resistance 0.16 Ohms

    0.25mH - 110 turns, 28 ft of wire, Est Resistance 0.20 Ohms

    0.32mH - 123 turns, 32.5 ft of wire, Est Resistance 0.23 Ohms


    Again, the 1.5Ω/10W Resistor should be mounted above the board about 1/2" for air circulation, the bottom side of the board is discolored due to that resistor overheating.
     
Loading...