TD condenser replacement

[melugin]

This has probably been addressed somewhere in this forum, but I haven’t been able to pull it up.  I need replacement condensers for a 1946 Johnson TD.  What will work?

 

[crosbyman]

based  on the excellent article  by Mr.Mohat  .22 uf seems acceptable  for most applications.

https://wrcoutboards.org/wp-content/uploads/2020/04/Part3_Sizing_Condensers_Correctly.pdf

conclusion….

I believe we can make the following generalizations and recommendations:
Motors, 1900s – (MASSIVE steel magnets, 2 pole / 2 pole construction, absolutely HUGE spark
coils)….use a .68 to 1.0uF condenser. Error on going too large, to protect the insulation in your
antique spark coil if possible…as long as your motor can be started easily.
Motors 1910s through 1920s (STEEL MAGNETS, 2 pole / 2 pole construction, very large spark
coil)….use a .47uF to .68uF condenser. Again, error on going larger than this, as long as you
can start the motor easily!

Motors 1930s and 1940s (Steel Magnets, typically 2 pole / 3 pole construction, “medium” size
spark coils)….use a .3 to .47uF condenser.

Motors 1930s and 1940s, (Alnico Magnets, 2 pole / 3 pole construction, smaller size spark
coils)….use a .22 to .47uF condenser.

Motors 1950s and newer (all)….just use a .22uF. It REALLY isn’t at all critical, apparently!
Also note that almost all 12V “Battery and Points” ignition systems seem to use something close
to 0.22uF as well, so this is sort of your ‘universal replacement’ value.

 

Joining AOMCI has priviledges 🙂

[stanley]

From Garry Spencer

[Mumbles]

Some info on using modern substitute caps from Mouser or Digi-Key.

https://www.aomci.org/forums/topic/substituting-old-condensers-with-modern-capacitors/

https://www.aomci.org/forums/topic/old-condensers-wanted-for-magazine-article/

[melugin]

Thanks.  Garry’s pages look familiar, they are probably somewhere in the stack on the desk in the shop.  Now to find the desk.

 

[Author]

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