"Gravity Wave Detector" Experiment Results
Experimental Report on the "I Don't Know What detector"
By Carl Brown
RR 1 Box 482
Whitefield, NH 03598 USA
For Free Distribution
In the file under phys/grav3.html, there is a circuit described, claiming to be a gravity wave detector. I constructed the circuit on a breadboard, and it did seem to exhibit some strange behaviour.
I am not claiming that it detects gravity waves, but it does detect something.
I replaced the 741 / 1458 op-amp with a TL082 dual Bifet op-amp. The TL082 has an input impedance of >1012 Ohms, and is therefore a charge-sensor, rather than a current sensor, as is the 741 type. In fact, the TL082 is fully capable of sensing differential voltages of < 1 millivolt at nanoamps of current. It is, therefore, emminently suitable to use as an amplifier of very small signals.
My first attempts proved the need for a second stage, as the output from the first stage was about 10 millivolts, indicating that the signal was very small indeed. The TL082 is capable of voltage gains on the order of 105, so the input signal from the capacitor is miniscule, far too small to be measured directly with a DVM, or even an oscilloscope. When I got the circuit operating, I fed the output to a Tektronix TAS-220 oscilloscope, and to a headset. The signal, for the most part, resembled white noise, which is not surprising, given the overall voltage gain of 105 or more. However, there appeared to be a nonrandom low frequency component. Several hours of tweaking produced the circuit shown in the diagram. The capacitors C2 & C3 filter out the "hiss", leaving a relatively clean signal below roughly 1 KHz, at the price of reduced signal strength. Tuning R2 to operate the first stage at just below clipping, and doing the same with R5, results in a near feedback condition, causing the first stage to resonate at a frequency primarily dependent on C2, given that R1 is fixed. This was found to be highly component specific, swapping capacitors of different types, even though of the same value, produced differing results. Again, this is a high impedance circuit, and small changes can produce large ones. In the test circuit, this resonant frequency was about 600 Hz. The resulting output signal resembles an amplitude modulated carrier, the 600 Hz being the carrier frequency, and the "I Don't Know What" being the modulator.
The IDKW signal is of low frequency, below about 30 Hz, down to about 2 Hz, a classic subsonic. I tried increasing the value of C1 to 900 microfarads, then to 2200, the ELF signal remained, but I was unable to induce oscillation. The high input impedance of the TL082 causes the the output to lock up if the feedback loop is eliminated, so I was unable to check the signal in open loop mode. The feedback resistor R1 serves to reduce the gain, but introduces the possibility of signal contamination. However, there is nothing in the circuit that would produce an ELF signal. C1 in the test circuit was a plastic encapulated unit, nevertheless, placing a finger on its case causes a 60 Hz disturbance nearly equal in magnitude to the ELF signal. That's how sensitive it is!
Operating the amplifier in the resonant condition shows a much wider dynamic range in the ELF signal, and an apparent increase in sensitivity. It also allows one to listen to the pulsations in the ELF, in a way. It is a very interesting sound, and I have absolutely no idea where it's coming from. The test circuit was battery powered, connected outside the board only to ground, and none of the ELF signals showed any relationship to the 60 Hz line power. There is obviously some force of sufficient strength to cause a voltage fluctuation in the capacitor, C1. Removing C1 results in a flat-line signal, proving that C1 is responsible for any signal.
In conclusion: I will continue to experiment with this device, and I hope that this report will lead others to do the same. There is a known connection between ELF phenomena and tectonic activity that needs to be researched. Gravity waves? I don't know...
The circuit described is just a starting point. If you think of it as a radio reciever, then this is just the tuner. A demodulator could be added, then,...? Use your imagination! And have fun!!!
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