Capacitor for Splitdorf low tension magneto system

[Frank Cerutti]

In 1909, Splitdorf introduced an ignition system comprising a battery, low tension magneto, non-vibrating coil, condenser and points set.

Does anyone have documentation which specifies the size of the condenser.

The ignition system was provided for both twin cylinder and 4 cylinder motors.

[Frank Cerutti]

Hi Mike

The question is about the capacitor size. Some documentation shows 0.47 micro Farads, another shows 22 micro Farads. There is a 50 times difference between the two.

 

[rsb]

0.22 micro Farads would be inline with modern style condensers. Perhaps there is a missing decimal point on the reference to "22 micro Farads"?

[Bloo]

I suspect you are absolutely right about the missing decimal point. 22 Microfarads in 1909 would have been physically huge.

 

I think it would be assuming a lot to guess that it operates on the same principle as a Kettering (modern points and condenser) ignition when on battery. I am pretty sure the Kettering ignition had not been invented yet in 1909 (corrections welcome if I'm wrong ).

 

 

 

 

Edited November 25, 2019 by Bloo (see edit history)

[cahartley]

Low tension ignition is for igniter ignition, not jump spark ignition which is high tension.

[Frank Cerutti]

Gents

Some of the points you have made are valuable and have given me a clue as to what is most likely to have occurred.

The Kettering design ignition system used from 1910 up to electronic ignition (1970s) used 20 to 30 microFarad condensers. Small motors using the design continue with that size condensers today.

Before Kettering in 1910, a regular source of ignition system condensers would have been the industry supplying condensers for Ford T trembler coils. So where would Splitdorf have found a source of reliable condensers without designing and building their own? They would have gone to the industry that supplied Ford. Hence, in the early Splitdorf documentation, (1909) the condenser is 0.47 microFarad.

Since Kettering, the little can with a tail, condensers rated at 20 to 30 uF, have been used exclusively on most petrol motors, even the 2 cylinder Maxwells.

Thanks gents. You have helped me understand.

[Bloo]

20uf to 30uf has to be a misprint. I can't imagine how or where those could be sourced in 1910.

 

Around 1930, a typical filter capacitor in a home radio was 2uf or 4uf, and it was gigantic. Technology didn't get them smaller until years later. 8uf was still a common filter size in 1940, and although shrunken, it was still physically ten times as large as an ignition condenser for a car.

 

The little cans with a tail seen on cars with points and condenser in the 50s, 60s, 70s vary by application, but are way below 1uf.

 

P.S. I have a car (1913 Studebaker 25) with a Splitdorf magneto. I'm not even sure it is low tension, but it does have points, and uses a hotshot battery for starting. The switch housing is really deep, and may contain a coil. I don't recall seeing a condenser, but it may be hiding inside somewhere. I would love to hear what you figure out.

Edited November 25, 2019 by Bloo (see edit history)

[oldford]

16 hours ago, cahartley said:

Low tension ignition is for igniter ignition, not jump spark ignition which is high tension.

My 1910 EMF (and most likely Bloo's Stude) uses a Splitdorf low tension magneto which simply supplies plus voltage to the high tension coil located on the dash board. The secondary of the dash board coil then sends the high voltage pulse back to the magneto's distributor to each of the spark plugs. VERY poor design, in my opinion. Most of these old Splitdorfs are not rebuildable, since much of the body is pot metal... Bosch's DU4 and DU6 magnetos were far superior...

 

Frank

[Layden B]

At the time these were made the idea of a transformer external to the magneto was a good idea, it allowed more insulation and better cooling. To built the high tension transformer into the rotating armature as Bosch did was iffy, their high quality managed to pull it off.

And yes this is a high tension jump spark setup even though the magneto produces low tension.

In my experience the survivability of Bosch over the other era brands is in the Bosch high quality of every issue, insulation, materials, design etc.