Date: Thu Apr 17 10:38:34 2008

Author: Bill Norwood

Subject: Re: Easy to make dual LED electroscope/charge detector

But don't overlook the much simpler (larger) neon lamp Bill Norwood

-----Original Message-----
From: [] On
Behalf Of Sean Crosby
Sent: Wednesday, April 16, 2008 6:25 PM
Subject: [tap-l] Easy to make dual LED electroscope/charge detector

Hi Tappers,

We are currently redoing all our undergraduate physics labs, and are
wanting to build an electronic electroscope to show students
that objects can detect the difference between positive and negative

We have found a cute electroscope based on a FET on the web:

The problem is (not really a problem, but we would like to make it
better) that it has one LED only. We would like to make one
that will light one LED for positive, and another LED for negative charges.

Anyone got a nice simple circuit to do it?

Cheers all,

Sean Crosby
PhD Student
School of Physics
University of Melbourne
Parkville VIC 3010