초록 ▼

An agricultural implement for spraying herbicide on weeds in a field without spraying herbicide on bare soil includes a photodetector circuit. The photodetector circuit includes a photodetector and an active filter. The photodetector is not AC coupled in parallel with an inductor/capacitor resonant

An agricultural implement for spraying herbicide on weeds in a field without spraying herbicide on bare soil includes a photodetector circuit. The photodetector circuit includes a photodetector and an active filter. The photodetector is not AC coupled in parallel with an inductor/capacitor resonant circuit which tunes the active filter. As a result, changes in photodetector capacitance due to changes in ambient lighting conditions are not impressed across the resonant inductor/capacitor circuit and therefore do not adversely change the frequency and phase characteristics of the photodetector circuit.

대표청구항 ▼

[ What is claimed is:] [12.] A system comprising:a photodetector having first and second terminals, the photodetector configured to receive light and to provide an output signal on the first terminal;an amplifier including:an input terminal connected to the first terminal of the photodetector, the a

[ What is claimed is:] [12.] A system comprising:a photodetector having first and second terminals, the photodetector configured to receive light and to provide an output signal on the first terminal;an amplifier including:an input terminal connected to the first terminal of the photodetector, the amplifier configured to receive the output signal from the photodetector; anda resonant circuit tuned to a selected frequency, the resonant circuit including a capacitance having first and second nodes;wherein at least one of the first and second terminals of the photodetector is electrically isolated from the first and second nodes of the capacitance of the resonant circuit.