Schumann Resonance Converter

Posted on Feb 6, 2014

Using a similar circuit to the LF block converter, I`ve made a Schumann Resonance Converter that moves the near-DC signals up to around 2 kHz for an ordinary soundcard. Here`s the maiden run plot: It seems to work! The fuzzy lines below 30 Hz are due to the Schumann Resonance. The image is from Spectrum Lab with an offset of 2. 048 kHz (the L. O. f

Schumann Resonance Converter
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requency). The 60 Hz is reduced by an unusual bridged-T notch filter that uses a little audio transformer as the inductor. I discovered that the inductance of such a transformer can be varied quite a bit with a very tiny current (or even a weak magnet). Only 100 uA of DC current will tune the filter many 10`s of Hz! Here`s a snapshot of the schematic so far: Circuit Starting on the left, the antenna should be a fairly long vertical mounted high in the air, away from trees. The lead-in cable will have significant capacitance, perhaps as much as 1000 pF, and that`s fine. (In fact, you might want to add a shunt capacitor if the hum is too big for the FET follower. If that`s the case, you might also try increasing the 220 pF capacitor, to, say, 470 pF, but that`s starting to eat into the gain at the higher Schumann resonance frequencies. ) The first 62 megohm bleeds charge off the antenna and the neon bulb or other gas discharge device limits the voltage. Those components are on my RF connector, not in the photo. The. 01 uF helps to isolate the JFET from the voltage and it should have a high breakdown voltage, just in case. The second pair of 62 megohm resistors bias the JFET gate to V/2, to give the source plenty of room to swing, since there`s likely to be a big AC hum signal. Those big resistors could be comprised of 3, 22 megohms in series. The 10 megohm is in the signal path, but its noise is well below the atmospheric...

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