Substituting capacitors for condensers

[The Boat House]

[dave-bernard]

yes.

[mercuryman]

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]

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]

This is interesting, but its from UK

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

[Buccaneer]

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]

.

• This reply was modified 4 years ago by The Boat House.
• This reply was modified 4 years ago by The Boat House.

[Mumbles]

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]

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

[Buccaneer]

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!

[Author]

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