DC Electric Motor Research Articles

Precise synchronization of high-speed DC motors

Abstract An electronic circuit has been developed which uses clock pulses to control and synchronize direct current electric motors operating at high velocities. The control functions with considerable precision, and can act to restore correspondence in phase when perturbations occur. Though specifically applied to regulate DC electric motors, the same logical principle can be adapted to other types of rotating mechanisms.

Cablegation: I. Cable Controlled Plugs in Perforated Supply Pipes for Automatic Furrow Irrigation

ABSTRACT A single pipe line served both the transmission and distribution functions at the head of a furrow ir-rigated field. Pipe size was selected to be slightly less than full when carrying the flow rate available on the ex-isting grade. Orifices were drilled in the pipe 30 from vertical toward the furrow side. Water was forced out of these orifices by a plug in the pipe. Position and move-ment of the plug were controlled by attaching it, with a cable through the pipe, to a reel at the inlet end with its rotation rate governed by a geared down, 12 v DC elec-tric motor, regulated in turn by a rheostat. A computer model predicted, and field tests corrobo-rated, that orifices near the plug had highest flows, with flow diminishing in orifices further upstream to zero flow at a distance determined by total flow, orifice size and spacing, and slope of the pipeline. As the plug passes a specific orifice, moving downstream at speeds from 3 to 6 m/h, flow begins at the maximum rate then decreases with time until the flow ceases. Effects on flow times and rates from orifices of varying orifice size, total water supply rate and plug speed, and of using multiple plugs and sleeving, are illu-strated and discussed.

A Microprocessor Automated Rillmeter

ABSTRACT THE measurement of erosion and rill development during natural or artificial rainfall requires a rill-meter that can be installed, make the measurements, and be removed from the plots quickly. The design cri-teria were that the device: (a) measure 300 or more sur-face elevations in less than 1 min., (b) have a vertical resolution of 1 mm over a 25 cm range, (c) be battery operated for remote field operation, (d) be light weight and compact enough for easy handling by two people, (e) be rugged enough for extensive field use, and (f) auto-matically record the data on an easily accessible medium. The rillmeter designed, constructed, and tested measures 312 surface elevations with sensing rods ar-ranged in three rows of 104 rods each. The rods are spac-ed 1 cm apart within the row and 5 cm apart between the rows. The rillmeter is attached to a frame that can be mounted quickly on field elevation stakes. A 12-V DC electric motor and a positive mechanical drive lowers a movable platform containing a grid of sensing rods that open individual electrical contacts upon touching the soil surface. A microprocessor scans all of the contacts several times before the platform moves 1 mm and stores the platform position at which each sensing rod touches the soil surface in an associated memory location. After all the data are in memory, the microprocessor stores them on magnetic cassette tape. Field and laboratory tests showed that the rillmeter does meet the design requirements.

A Hand-held, Drift-free Herbicide Applicator

Abstract A hand-held, drift-free herbicide applicator has been developed from the Vibrajet (Plant Protection Ltd). The spray nozzle is a plastic sleeve with holes punched in it. By varying the position of the sleeve, interchanging different sleeves and changing the height of the nozzle, the swath width can be varied. A 12 V DC electric motor vibrates the nozzle body. Liquid herbicide is carried in a plastic container on the back of the operator. Discharge rates and swath widths, and the cost of this adaptation of the Vibrajet are given.