Page 291 - Electromechanical Devices and Components Illustrated Sourcebook

Chapter 15 Sensors 253

Mounting Holes
Wind Vane
Rotating Brush
Copper Pad
Copper Slip Ring
Fixed Brush
Connector
Hub

PC Board

Figure 15-15 PC Board Rotary Position Indicator

NE
Printed Circuit (PC) board rotary position indicators provide
Digital
a simple method to construct low-cost resolvers. Figure 15-15 Panel Potentiometer
shows a typical PC board rotary position indicator. This par- Indicator Controller
ticular unit is a single-pole, 15-position unit. It should be Figure 15-17 Digital Wind Direction Indicator
noted that these types of positioners can be configured to have
several tracts, with specific positions and/or base two outputs.
Figure 15-16 shows a typical application for a PC board
position indicator. The hub of the sensor is mounted to the
Mounting Holes
shaft of a wind vane. The outputs are wired to a circular array
of panel lights, which indicate the points of the compass. The Z Ring X Ring
panel lights continuously indicate the position of the wind Rotor
Adjustable
vane. Pivots Z Resolver
X Resolver
Y Ring
Wind Vane

Frame Y Resolver
Figure 15-18 Digital Gyroscope Position Indication

nnw N nne
NW NE
nww nee One of the most common rotational parameters to monitor
Panel W E Position
sww see is revolutions per minute (RPM). This can easily be accom-
Indicator SW SE On/Off Indicator
ssw S sse
Battery plished by using a generator and voltmeter, as shown in
Figure 15-19. The faster the generator is turned, the higher the
voltage reading. The displayed volts correspond directly with
the input RPM of the generator. Standard generators rarely
Figure 15-16 Wind Direction Indicator

A wind position indicator can be configured using a digi-
500 1000 1500
tal potentiometer, as shown in Figure 15-17. In this case the 2000
RPM Voltmeter
output of the potentiometer is connected to a controller or
computer. The controller drives a panel display that indicates
wind direction. − +
Detecting motion in three dimensions is generally the duty
of a gyroscope. These detectors are most commonly found in
aircraft, where they supply base line attitude information to Input
the navigation system and pilot. Figure 15-18 shows a three-
axis gyroscope equipped with digital potentiometers. The out-
puts of the potentiometers are connected to a digital controller
and altitude information is generated for the navigation sys- Small DC Generator
tem and displayed for the pilot. Figure 15-19 Generator RPM Indicator