Looking for an electric field mill, a little instrument that measures the electric field in the air above it. Boltek makes these. Others would be considered. Other field measurement instruments might do.
Also looking for a magenetometer/gaussmeter for long term geomagnetic field measurements.
The sort of stuff associated with weather, day to day and the occasional thunderstorm, perhaps 100 to 1000 volts/meter.
There are a variety of web pages describing how you can try to build one of these yourself. Scientific American, Amateur Scientist, published one in 1999 I think and there are others out there. (but with my mechanical skills I think that trying to build something to spin one metal garbage can inside of another and in close proximity and at 7000 rpm would earn me a spot on the "World's Stupidest Person" television show somewhere)
I'm also looking for a magnetometer for geomagnetic field variation measurement.
Anyone know of a source of either of these, perhaps used?
Because of the threat of damage to launch vehicles, field mills have been used extensively for lightning research and prediction at the Kennedy Space Center. If they didn't invent them, they probably improved them.
There is a chance you can find some old ones that were replaced or upgraded. Check out
They are responsible for disposing of all kinds of scientific and industrial equipment that is surplus to the Space Program.
If you can find reports published by some of the researchers, there may be e-Mail addresses you can contact for more information. Someone working there might be more aware of when equipment is to be replaced or upgraded. If you are associated with a university research program, it might be possible for them to transfer surplus property directly instead of auctioning it off.
Take a look at New Mexico Tech Langmuir Lab website. Their EE department build them. Plenty of detail, including circuits. They're not difficult to make, if you have machining facilities (or even if you don't, and don't mind a bit of crudity). Calibration is a breeze.
One day, I shall do one. Probably after the Schumann resonance antenna :-)
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more