Hi Oren:

A High voltage transformer drives the neon. I suppose that you command the primary of that transformer with a electromechanical relay. If this is correct what you can do is to use a solid state relay SSR ( zero crossing switch) to minimize noise problems. The input to the SSR can be driven directly with a pin-port.

If you connect more than one neon lamp what you can do is to insert between the main AC power line the SSR and the sequence for changing the state of the neon should be

1. Turn off the pin port that drive the SSR
2. Wait for a delay of 20 msec ( 50Hz AC line)so the SSR effectively turns off.
3. Change relays that drive the primary of the transformer.
4. Wait a delay of 10 msec to avoid any bounce in the contact relay.
5 Turn on the pin port of the SSR.

I hope this will help you.

Good luck}
Daniel