Here's an example of using a more modern device, oudin coil. Same thing used in more expensive devices specific to leak checking that could cost you from $99-$200.
My friend Harold Lasswell was able to make a leak checker for under $40.
Welcome to Taming Lightning, I'm Percy Echols II. I'm the creator and host of Taming Lightning, as well as the emerging plasma tech at Pittsburgh Glass Center, where I'm researching and developing a space to explore Plasma and Neon Light as an Artist Medium.