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Monitoring the Earths electric field.
Most of these disturbances are quite strong and easily detectable. You could try a large coil of wire, wound over a non iron former, and connected to the input of an audio amp. 50 hz crud will be an issue, but a filter to filter out 50 hz, 100 hz etc isn't too hard to make, especially if designed as an active filter with a pre amp.
Another thought is an untuned rf amp, say the intermediate frequency of a old radio at 455 kc. Simply disable the local oscillator, and feed a input from a coil of wire directly into the intermediate frequency amplifier. Old radio are everywhere at the tip shops. The advantage of this would be the natural discrimination against 50 hz mains crud.
My detector is simply a 1940's 6U7 radio pentode valve, with 800 volts odd between the cathode and anode, a very high value grid resistor of 1 million meg ohms, and a long wire aerial. Connecting an audio amp to the output gives all sorts of interesting pops, clicks from electric fences etc.
It now feeds a commercial data logger and operates from a PC running..... windows XP !
The second channel is connected to a seismograph, and has no difficulty detecting most of the quakes that have happened in the world lately, along with vibrations from cars on the road and people walking around.
As an aside, when the sensitivity of the data logger is at max, and AC coupling it to the electrometer (internally done with a switch on the front panel), people walking around up to 20 meters from the detecting wire are easily detected, as they disturb the standing earths electric field. This used to be toted as e field detection, but I haven't seen much about it for some years.
As alluded to in a previous post, electrical storms, nuke tests, earthquakes and so on, all disturb the normally stable electric field of around 500 v/m at sea level. Having a network of detectors linked together and plotting the results on a map, joining places of equal electrical potential, not barometric pressure, would show the buildup and decay of electric charge associated with a storm, long before any sign is visible to either an observer, or weather radar.
Anyway, the results of the above tests are the subject of an Australian Patent held by me, anyone want to have a go ? I'm too old and cranky now !
Several years ago, the Earth passed through the tail of some comet or other, and the resulting discharges showed up on the chart, as a cyclic change of potential. I have so many paper charts i don't think I could find that one, but the gear is not limited to terrestrial events. The underground nuke tests by the French in the Pacific were also observable, probably due to the EMP, and then the earth quakes associated with them.
Better go and do some work, cheers all.
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