Flow sensor based on electrical capacity

A flow sensor apparatus for monitoring a directed stream of an agricultural product from an application port, at the end of a supply tube on a planter, said directed stream having a target directed portion and an off-target portion, said flow sensor apparatus comprising:

• (a) a first electrically conductive plate;
• (b) a second electrically conductive plate disposed a distance away from the first electrically conductive plate;
• (c) a first electrically nonconductive surface disposed to connect edges of the first and second electrically conductive plates;
• (d) a second electrically nonconductive surface disposed to form a volume, said volume bounded by surfaces comprising the first electrically conductive plate, the second electrically conductive plate, the first electrically nonconductive surface, and the second electrically non-conductive surface;
• (e) a signal conditioning circuit, having an input and an output, with the first and second electrically conductive plates;
• (f) means for measuring a circuit time-delay from the input to the output of the signal conditioning circuit;
• (g) means for correlating the measured circuit time-delay to the electrical capacity between the two electrically conductive plates;
• (h) a dielectric constant determining circuit to determine an effective dielectric constant between the first and second electrically conductive plates;
• and
• (i) a computational function to correlate the effective dielectric constant to a presence of material inside the volume,
• wherein said first electrically conductive plate, said second electrically conductive plate, said first electrically nonconductive surface, and said second electrically nonconductive surface are positioned external to said application port and thus positioned to provide measurement of the agricultural product, and
• wherein an operator is warned if the agricultural product is not applied in the proper position relative to seed being dispensed from the planter.