View Single Post
Old 01-18-2013, 12:45 AM   #16
Benson
Senior Member
 
Join Date: May 2010
Posts: 2,579
Default Re: Snap-On MT-335 Coil Tester...question

Dudley,

Maybe the neon bulb is used to determine the polarity of the spark from the coil during testing.

See this video on U Tube:

https://www.youtube.com/watch?v=OKPPbLXNOt0

The neon glows around the left "pin" of the bulb with a negative voltage applied and the other "pin" if a positive voltage is applied.

I remember seeing neon bulbs hooked to AC in old radios with vacumn tubes that glowed around both "pins" as AC current changes polarity 60 times a second so it appears that both "pins" are lit at the same time ...

Most pilot neon lights on radios ran on about 100 volts.

Notice that the fellow in video used eight 9 volt batteries or about 72 volts for his experiments.

Last edited by Benson; 01-18-2013 at 07:18 AM.
Benson is offline   Reply With Quote