VIIIScan the text and decide whether the following sentences are true or false. Discuss them with your partner.

1 Secondary power sources include only electronic power supplies.

2 Many of the electrical and electronic systemsin naval aircraft require precise

voltages to operate.

3 These power supplies come in many differentshapes, sizes, and designs, but all

operate in different way.

4In high performance aircraft, avionics systems helpthe pilot only communicate.

5Radar and autopilot (AFCS), ease thepilot’s workload.

6 Each of these systems requiresprecision voltage inputs for proper operation.

7 Each avionics system has its own powersupply.

8 The power supply requirements are for a 100-/308-volt, three-phase,four-wire,

600-Hz electrical power input.

9 Full-wave rectifiers produce ac voltages.

10 Each pair of rectifiers (either CR7 and CR10 or CR8 and CR9) conducts during

alternate half cycles of the dcinput from the secondary coil of step-down

transformerC7.

11 The unfiltered ac provides power to operate lightsand relays for internal

operation of the system and feedsa filter network.

12 Also, filtered ac supplies transistorbias to the electronic amplifiers in the

autopilot system.

13 The circuit develops precisiondc voltages.

14 Diode CR9 is a Zener diode that develops aconstant ac voltage.

15 If the ac inputvoltage at the top of R1 increases, CR1 will conductharder.

16 If thevoltage decreases, CR1 conducts less; less voltagedrops across R1.

17 This maintains the voltage at theanode of CR9 at a constant, precision

potential.

18If no current flows through R2, the same potentialpresent at the input of

amplifier A1 and on the anode ofCR1 is the same.

19 Feedback voltage through resistors R3and R4 control the gain of amplifier A1.

20 If thecombined resistance values of R2 and R5 are the sameas the resistance of

R2, the potential of the outputvoltage and the anode of CR1 are the same.

21Naval aircraft have backup (emergency) electricalpower if primary sources of

electrical power fail.

22 The various ways of supplying this emergency power areaircraft storage

batteries, auxiliary power units, and hydraulic motor driven generators.