Reinventing the neon test screwdriver

The classic neon test screwdriver has been around for a long time. It relies on the sensitivity of a small neon indicator bulb in series with a safety resistor to give a slight glow when touched to live electrical connections by finding a return current path through the user.

It has a few weaknesses. It's very dim to start with, but even dimmer when the user is well insulated from ground, some have inadequate safety resistors, and it's a very vague test that is not always reliable.

With the sensitivity of modern LEDs I thought it might be worth testing to see if they could be substituted in place of the original neon indicator to provide a brighter indication.

Note that this experiment involves direct electrical contact with mains referenced circuitry. It is imperative that the resistor is chosen with safety in mind, and that the internal wiring can't short out the safety resistor accidentally.

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