There is disclosed a signal-seeking, scanning superheterodyne radio receiver operable on all four bands comprising the public service radio frequencies. The receiver uses a single oscillator and appropriately controlled frequency multipliers to generate the required local oscillator signals. Circuitry is included for tracking the radio frequency portions of the receiver to tune them for optimum operation as the receiver is tuned to different portions of the individual bands. The tracking circuit...

A monitor for use in a multi-row seed planting apparatus is provided for detecting seeds passing from a seed bin to a plurality of seed dispensers and for indicating by row number an improperly operating dispenser. A seed sensor is placed in the seed flow path of each dispenser to provide an output signal indicating that seeds are continuously flowing along the seed flow path through the dispenser. A two-digit seven-segment readout display is provided on the monitor and is coupled to the seed di...

A vehicle detector, comprising a tuned inductive loop adapted to produce a high frequency field which will be disturbed by vehicles entering the field, an oscillator for supplying a high frequency energizing voltage to said loop, a phase detector for comparing the phase of said voltage across said loop with a reference voltage derived from said oscillator, said phase detector being adapted to produce a control signal when the phase of the voltage across said loop is disturbed by the entry of a v...

A firing-angle control circuit having means for generating a ramp control voltage and for utilizing an electronic switching means to compare the ramp voltage with the instantaneous value of an error signal. Whenever an error signal bears a predetermined relationship to the instantaneous amplitude of the ramp signal, the switching means is deenergized and the signal source is coupled to the load. The ramp control voltage is phase related to the signal source, and hence the comparison between the ...

There is disclosed a signal-seeking superheterodyne radio receiver for use on the public service radio frequencies capable of scanning among a plurality of channels and using frequency synthesizing apparatus to generate the required local oscillator signals. An electrically programmable, nonvolatile memory is included for controlling the frequency to which the receiver is tuned when it is operative on any given channel. The receiver includes a plurality of manually operated switches for selectiv...

There is disclosed a liquid velocity measuring apparatus comprising an actuable generator for providing a relatively high frequency signal to a transmitting transducer for directing an ultrasonic wave into a conduit through which liquid is directed. A receiver transducer is disposed to receive the acoustical wave as reflected from the liquid, and to provide an output signal to be amplified and demodulated to provide a train of high frequency pulses, the frequency of which is indicative of the ve...

A wireless seed detecting and monitoring apparatus includes one or more transmitter units mounted at the seed planter and a receiver unit mounted in a monitor console located at a remote location. Seeds being planted produce a signal which modulates an r-f transmitted signal during the planting operation. A receiver is responsive to the r-f transmitted signal and detects the modulated signal information corresponding to seeds being planted. This detected signal is then delivered to monitoring ci...

A grain sample moisture tester comprises a reference oscillator and a variable oscillator, the latter having a capacitor across its tank circuit that constitutes a test cell such that the dielectric constant of the capacitor is modified in accordance with the dielectric constant of the grain sample. The test cell is suspended on a frame or chassis such that when a predetermined amount of grain has been introduced into the test cell, a switch is closed to initiate a digital measuring circuit to p...

A digital reading grain moisture tester is disclosed in which the frequency of an LC oscillator having as one element a capacitive cell containing a measured weight of the material under test is determined by counting the number of cycles occurring during a period of defined length. Circuitry is provided to vary the length of the counting period to compensate for differences in the physical properties of the grains which may be tested and for variations in the sample temperature. Automatic balan...

The embodiment of the invention disclosed herein is directed to a sensing device for determining the passage of high velocity, relatively small articles such as seeds being planted through high volume automatic planting apparatus used by farmers. The sensing device has a pair of spaced apart ultrasonic transducer elements, one acting as a transmitter and the other acting as a receiver. The driving circuit for the transmitting transducer has a feedback path coupled to the receiving amplifier of t...