neon sign transformer confusion

[Tesluh]

had to modify this nst to get it to work but at least I finally have a high frequency nst with a firing spark gap.  need to start tuning the coils.  This will get me started but will continue to look for a better option as far as high frequency power supply.

[Magluvin]

Whats the yellow wire to the left on the xfmr? Did you try that as the ground screw alternative?

Glad to see you going at it.

Mags

[Tesluh]

That is the "ground" wire for if it were used as a neon power supply, it seems loosely attached to the output of the secondary (mohms or kohms resistance) but it is directly connected to ground pin on input plug.  attaching it just like the other wire is now resulted in nothing.  no spark.  there was something very special about the way the Bertonee and that one in that video are built internally.  I just got a different one same part number as the one in the video but different mfg, same threaded stud as the bertonee but no spark when circuit is attached like Don's.

[mscoffman]

The reason for the CT center tapped ground in the neon transformers is so there is always +4KV or -4KV from each neon light pole/probe to ground. That way if you accidently
touch between eighter probe of the neon bulb and ground you get only a max of 4K volts rather than the whole 8K volts/nothing.  There shouldn't be any reason you can't design
Don Smith RF circuit to be ungrounded/balanced then in the final transformer secondary have it become ground referenced again.

[Tesluh]

Are you saying l1 primary side not grounded and l2 secondary side grounded?  I agree, a ground somewhere on the primary side might help (Don said this was the key to "getting amps" out of the system) but it shouldn't be necessary to pulse the primary coil.  I believe (and please correct me if I am wrong) that using both legs back to center doubles the frequency of the output so instead of about 35khz it would be more like 70 kHz.