Did you ever wonder how the charges were changing in the clouds directly overhead during a thunderstorm? Does an early-warning voltage exist right before a strike or do the charges jump from cloud-to-cloud too quickly? Is the polarity of the charge always the same? Build the Cloud Charge Monitor and watch the charges ebb and flow for yourself!

The Cloud Charge Monitor is an extremely sensitive device capable of detecting subtle (and not-so-subtle) changes in the accumulated charge overhead. The device consists of a charge-sensing antenna, a 60 Hz notch filter, a self-zeroing integrator, a signal limiter, and a leakage zero adjustment. The monitor is a fairly sophisticated device with a few special construction requirements and beginners may wish to solicit some help with construction and testing. For the more advanced experimenter each circuit function is described along with possible variations and performance enhancement ideas.

Download the Cloud Charge Monitor pdf file.