geoff wrote:
In message , Pete Verdon writes

How are they supposed to work?

Is it just that the current flow is very small, and almost all the
voltage is across the neon? Can anyone with a better grasp of
electrical theory explain?

Chuck it and spend a tenner on a meter

I already have a meter. It's somewhat less effective than the
screwdriver at doing up terminal screws.

(You snipped the bit where I said I bought it as a screwdriver, and
didn't intend to use the neon part.)

Pete