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G-Factor Gravimeter Circuit #600-A
G-Factor Gravimeter Circuit #600-A was fabricated in an aluminum box 2" x 3" x 5" in size. All operating controls were brought out on the top face, including an output jack and a large (2.75" wide) calibrated meter to give a display of the output voltage. A dual 9-volt battery supply is self-contained in the unit. The unit was primarily designed as a g-field gravimeter, to give the long-term highly averaged value of the earth’s g-field, although a somewhat faster response time is also provided for.
The circuit used in this unit is a bipolar device version of the gravimeter described in the article "Simple Gravimeter Meters Display Interesting Gravity Effects". It uses the readily available 1458 operational amplifier (op-amp) device in a typical gravimeter circuit, but where the operating parameters were adjusted for this particular mode of operation. A wide range of sensitivity and gain control were provided for, as well as two levels of output integration. The output meter is used to give a relative indication of the g-field levels (on a 1 mA meter movement having a full scale reading of 5 volts). The gain and off-set controls are nominally set to above their mid-positions so as to keep the output voltage on scale. Normally, the filter is kept in the Low position for a highly integrated output as a g-factor meter, but may be switched to the High position to enable the observation of gravity ‘impulses and ‘shadows’ which are mainly due to events in our own Milky Way Galaxy system.
Operation of this unit is simple: Set the gain and off-set controls to slightly above their mid-positions; set the filter to High and the sensitivity control to about its mid-position. Now turn on the power supply and allow the unit a minute or two to stabilize. Some slow fluctuations in the output voltage should now be noted. Slowly adjust the gain and off-set controls upwards, so that the nominal output voltage is near the 0.6 reading on the meter scale (i.e., 3 volts). The unit is now responding to the Milky Way Galaxy fluctuations (to a large measure).
Now turn the filter switch to its Low position. This will introduce a very long time constant in the output, due to the 0.1 farad capacitor now switched in. The unit is now a sensitive g-factor type of gravimeter, where a scale reading of say 0.6, can now be related to a g-factor of 32 ft/sec2 (or 980 cm/sec2 ). The daily (diurnal) variations in the earth’s g-field can be noted in this mode of operation and the relative (per cent) change can be determined from these readings. However, note that the unit will read an increase in the g-factor as a down scale reading on the meter.
Unit #600-A is primarily a sensitive gravimeter as used by the oil and mineral prospectors. However, it is also very useful to follow the subtle daily variations in the earth’s g-field which are due to massive effects in this universe and note the possible severe variations which cold possibly affect out jet stream patterns and thus our earth weather patterns! It is believed that such variations were responsible for much of the anomalous weather conditions seen since about December 1986!
Good experimenting to all!
Figure 1: Gravimeter Circuit #600-A ~
Notes: (1) Circuit is bipolar version of Circuit in Figure (1) of the article "Simple Electronic Gravity meters Display Interesting Gravity Effects"; (2) To avoid going into the negative mode of operation, place a 10K resistor in the ground leg of the gain control; (3) Built-in meter range: 0-5 volts; (4) Filter range: High in Galaxy; Low for g-factor; (5) Increase in g-factor reads down-scale!