Substituting capacitors for condensers

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  • The Boat House
    The Boat House


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    #198199

    You're only as smart as the person you're talking to.

    Avatar
    dave-bernard

    US Member - 2 Years
    Replies: 1362
    Topics: 18
    #198227

    yes.

    mercuryman
    mercuryman

    US Member - 1 Year
    Replies: 448
    Topics: 162
    #198230

    Capacitors Condensers the electrical circuit reacts the same with either, the are different names for the same thing. The voltage is the breakdown voltage rating. If you exceed it the capacitor could burn open and be useless . When the points open the voltage induced in Primary winding ( wires connected to points and ground is in excess of 100 volts . I use 450 volt capacitors but 650 volt can’t hurt. I have checked a lot of condensers with my MERC O TRONIC and they all test about 20% high or more on capacitance test ( UF micro farads ). And a lot of then are shorted . Here are some different magneto UF spects. Bendix .17 to .21 uf, Phelon .15 to .19 uf , OMC .16 to .24 uf and Martin .16 to .20 uf. I think the .22 uf 450 volt capacitor is a good substitute for all these magnetos. You can find them in different physical sizes to fit your application. If you want to go to the trouble you can open up a condenser clean it out and stuff in the capacitor it will look better but work the same as a bare capacitor . One reason for capacitor is to reduce arcing when points open, it there value is out of specs it can causer metal transfer from one contact to the other. I think capacitors are a very good replacement.

    Tom
    Tom

    US Member - 2 Years
    Replies: 471
    Topics: 46
    #198231

    There’s one more specification for a condenser, that’s the dV/dT, or how fast the component and move the voltage. To function in a magneto circuit, the value has to be pretty high, a lot higher than most uses. I think if you search this site a bit more, you can find a little more information on which ones have worked well in magneto applications. (Try “MKP 1839”.) I don’t know what the markings on the one shown above mean, so I can’t rule it out. The Vishay MKP 1839 HQ series should be OK.

    Tom

    mercuryman
    mercuryman

    US Member - 1 Year
    Replies: 448
    Topics: 162
    #198257

    This is interesting, but its from UK

    https://www.themagnetoguys.co.uk/condensers-theory

    Buccaneer
    Buccaneer

    US Member - 1 Year
    Replies: 4605
    Topics: 790
    #198270

    This appears to be the capacitor mentioned in the UK article, available from DigiKey.
    I don’t see the dV/dT rating, but perhaps it’s listed somewhere.

    https://www.digikey.com/products/en?mpart=PME271M522MR30&v=399

    Prepare to be boarded!

    The Boat House
    The Boat House


    Replies: 3398
    Topics: 84
    #198288

    .

    You're only as smart as the person you're talking to.

    Mumbles
    Mumbles

    Canada Member - 2 Years
    Replies: 4894
    Topics: 268
    #198397

    Capacitors are not created equal as they are designed for a specific purpose. Using the wrong cap in a mag with a correct uF rating might not give you the results you’re expecting as it will probably fail in a short time.

    Jeff R. and Vishay solved this problem a few years ago when figured out these High Quality Vishay caps would be the correct ones to use in magnetos. They are available from Digi-Key in different uF ratings and can be installed in parallel to get a correct rating for your application. Clicking on the datasheet button will give you all the info on them.

    https://www.digikey.com/products/en?vendor=0&keywords=bc2609-nd

    https://www.digikey.com/products/en?keywords=BC2607-ND

    squierka39
    squierka39

    US Member - 2 Years
    Replies: 581
    Topics: 32
    #198412

    These were suggested by another member. I have installed them in a few motors with good bench results. Have not run any yet.

    04FA1E7F-4D4A-45C6-860C-CB967E3AE28D

    Attachments:
    Buccaneer
    Buccaneer

    US Member - 1 Year
    Replies: 4605
    Topics: 790
    #198415

    Here’s the list of the caps I’ve been using the last couple of years, gleaned
    from information on this site.
    However, I was recently told that the .20 axial ones listed (little square orange ones)
    may not be up to the task. Non of my motors get run “hours” on the lake,
    but can say I’ve run some around the lake for an hour and they kept running
    great……. guess I’ll find out someday out in the middle of the lake if they fail.

    ==============================
    .1 UF Axial
    Digi-Key part #
    BC2607-ND

    Manufacturer Part Number
    MKP1839410084HQ

    Description CAP FILM 0.1UF 5% 850VDC AXIAL

    Detailed Description 0.1µF Film Capacitor 400V 850V Polypropylene (PP),
    Metallized Axial

    ==================
    .15 UF Axial

    Digi-Key Part Number BC2608-ND

    Manufacturer Part Number
    MKP1839415084HQ

    Description CAP FILM 0.15UF 5% 850VDC AXIAL

    Detailed Description 0.15µF Film Capacitor 400V 850V Polypropylene (PP),
    Metallized Axial

    ==================
    “Orange”
    .2 UF
    0.2µF Film Capacitor 400V Polypropylene (PP), Metallized Radial

    Digi-Key Part Number P12106-ND

    Manufacturer Part Number
    ECW-F4204JL

    Description CAP FILM 0.2UF 5% 400VDC RADIAL

    Detailed Description 0.2µF Film Capacitor 400V Polypropylene (PP),
    Metallized Radial
    ==================

    .22 UF Axial

    Digi-Key Part #
    BC2609-ND

    Manufacturer Part Number
    MKP1839422084HQ

    Description CAP FILM 0.22UF 5% 850VDC AXIAL

    Detailed Description 0.22µF Film Capacitor 400V 850V Polypropylene (PP),
    Metallized Axial
    ==========================

    Prepare to be boarded!

    The Boat House
    The Boat House


    Replies: 3398
    Topics: 84
    #198449

    .

    You're only as smart as the person you're talking to.

    Mumbles
    Mumbles

    Canada Member - 2 Years
    Replies: 4894
    Topics: 268
    #198451

    Buck: The 1839HQ series are definitely known to work and be reliable.

    If a cap fails, it shouldn’t make your motor quit instantly but the uF rating will shoot off the high end of the scale and the points will burn prematurely causing a miss. Test their rating again after running the motor for a while, maybe 20 minutes, again after one hour, and see if it has changed any.

    When I started experimenting with caps, I bought a bunch from Mouser but they had a lower voltage rating and might have had a different composition than the Vishay HQ caps and they wouldn’t last. Now I have a bag of them collecting dust.

    22-MFD-Caps

    This tool has to be one of the best investments I’ve ever made as it identifies the item you are testing and gives an accurate reading in picofarads instead of microfarads. It will identify different types of transistors, diodes, resistors, and capacitors etc. I keep one in the house for working on vintage audio equipment and another one out in the garage as a dedicated outboard tool. Highly recommended!

    https://www.banggood.com/DANIU-3_5inch-Colorful-Display-Multi-functional-TFT-Backlight-Transistor-Tester-p-1083042.html?rmmds=search&utm_source=tradetracker&utm_medium=tradetracker_no&utm_campaign=0&utm_content=227735&aff_key=0%3A%3A227735%3A%3Ajp7tsnaz7s02ko3q02n08%3A%3A%3A%3A1543811985&aff_campaign=16952&cur_warehouse=CN

    Avatar
    dave-bernard

    US Member - 2 Years
    Replies: 1362
    Topics: 18
    #198456

    for testing why not mount the caps on the block and run wires into the mag then you wont have to pull the flywheel to check.

    Buccaneer
    Buccaneer

    US Member - 1 Year
    Replies: 4605
    Topics: 790
    #198462

    Mumbles, it was the P12106-ND, little orange radial caps
    that I’m worried about, and used a bunch of.

    I’ve only been using the listed axial caps now.

    On my Flambeau project, I’ve adapted some B&S caps,
    so I could terminate the wiring on the condenser as
    the original Eisemann condenser….. will see how that works.

    Prepare to be boarded!

    Tom
    Tom

    US Member - 2 Years
    Replies: 471
    Topics: 46
    #198469

    The length of the leads affects performance. At least that’s what I noticed when I tried that.

    T

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