When I first started working at HIPAS Observatory in around 1994, my task was maintaining a paper chart recorder that measured Telluric currents. Telluric currents are natural electric currents that flow near the surface of the earth, which are induced by auroral activity and other phenomena. They're surprisingly easy to measure, but don't let any "free energy" idiots tell you they are a source of free electricity...or even cheap electricity. They are feeble currents, but can be quite active, and rather sensitive indicators of geophysical things happening both near and far.

All you need to measure telluric currents is a couple of ground rods, preferably sunk at least 100 feet from each other. A single wire from each of the rods feeds the input of a high gain differential amplifier (instrumentation amplifier), and then some kind of data logger. (You can use a chart recorder if you like, but datalogging ADC modules are available really cheap....or you can even use an arduino-based A/D converter.

It's better if you have two pairs of telluric rods at right angles, because you never know the orientation of the telluric currents ahead of time...and a nice quadrature system will allow you to figure that out. (Normal I/Q detection that is used for all modern SDR and DSP radios_). With a proper quadrature system, you can figure out ANY angle of current, not just parallel or perpendicular to a pair of rods.

Anyway....I have this DATAQ 8 channel recorder that's not doing anything, so I thought I'd set up a quadrature monitor at the QTH and see if I notice anything interesting. Let me know if you're interested in this science, as well, and maybe we can compare notes. And win a Nobel Prize. Or at least an Ignoble prize.

 

Ever since visiting the observatory in Greenbank, I always thought it would be cool to setup a pulsar detector.

 

I understand these currents are generally in the VLF range, but how do you attribute them to any specific source or distinguish them from local man-made currents?

 

All you need to measure telluric currents is a couple of ground rods, preferably sunk at least 100 feet from each other. A single wire from each of the rods feeds the input of a high gain differential amplifier (instrumentation amplifier), and then some kind of data logger.

What voltage magnitudes are typical for this kind of setup?

 

Back a long time ago, even before fire-bottle electronics, signals were sent through the ground. In WW#1 the allies were able to listen to the German filed phones because they used the ground as one side of the signal loop. And through ground communication has been played with by many folks ever since, and probably before. The voltages vary from several volts to several microvolts, depending on the sources.Power lines and lightning produce the highest voltages, static charges and experimentors produce the smaller currents. There are a number of articles about them.

 

Here's some practical (if slightly old) info on the hardware and such.

 

Here's some practical (if slightly old) info on the hardware and such.

Interesting. Thanks.