How much do you know aboutthe 555 Timer IC?.

Take this test and find out . . .

-by Colin Mitchell

Take this test both before and after reading the 555 article and compare yourresults.This type of test is classified as OBJECTIVE or MULTIPLE-CHOICE. It ismuch more effective than it appears. Multiple-choice can be "off-putting" anddecision-making is made more difficult. That's why it is so good. In addition,it is very easy to have computer-scoring and provided enough questions areasked, the results are very accurate. Attempting this type of test willstrengthen your knowledge of a topic. By the simple fact that it asks the sameinformation more than once, with the result that the facts are passed to yourlong-term memory.

QUESTIONS:

1. The function of Pin 3 is:Control VoltageDischargeOutputResetThresholdTrigger

2. The function of Pin 6 is:Control VoltageDischargeOutputResetThresholdTrigger

3. The function of Pin 5 is:Control VoltageDischargeOutputResetThresholdTrigger

4. The function of Pin 4 is:Control VoltageDischargeOutputResetThresholdTrigger

5. What is the function of the Threshold pin?

To charge the capacitor "C"To discharge the capacitor "C"To detect when the capacitor is "HIGH"To detect when the capacitor is "LOW"

6. What is the function of the Discharge pin?To charge the capacitor "C"To discharge capacitor "C"To detect when the capacitor is "HIGH"To detect when the capacitor is "LOW"

7. What is the function of the Trigger pin?To charge the capacitor "C"To discharge the capacitor "C"To detect when the capacitor is "HIGH"To detect when the capacitor is "LOW"

8. What is the function of the Reset pin?To discharge the capacitor "C"To reset the chipTo make the output of the chip "HIGH"

9. The Discharge and Output are:In phase with each otherOut of phase with each other

10. What does pin 6 do?Charges the capacitor "C"Discharges the capacitor "C"Detects the HIGH on capacitor "C"Detects the LOW on capacitor "C"

11. When pin 2 detects the voltage-level on the capacitor, does the capacitor begin to charge or discharge?

ChargeDischarge

12. What does pin 2 do?Charges the capacitor "C"Discharges the capacitor "C"

Detects the HIGH on capacitor "C"Detects the LOW on capacitor "C"

13. In the following diagram, is the output predominantlyHIGH or LOW? Remember: Pin 7 and 3 act "in harmony"

HIGHLOW

14. To increase the output frequency of a 555:Increase the value of capacitor "C"Decrease the value of capacitor "C"

15. If the resistors in Q13 are swapped, does the output frequency change?

It increasesIt decreasesLittle or no effect

16. What does pin 7 do?Charges the capacitor "C"Discharges the capacitor "C"Detects the HIGH on capacitor "C"Detects the LOW on capacitor "C"

17. If the value of R1 is increased:

The output frequency increasesThe output frequency decreasesThe overall frequency does not alter

18. Name the resistor(s) that effect the timing of the "LOW OUTPUT":R1 and R2R1 onlyR2 only

19. For a 5v circuit, if pin 4 is taken to 1v, does the chip reset?YesNoCannot be determined

20. When pin 2 detects the voltage-level on the capacitor, what happens to the output?

It goes HIGHIt goes LOW

21. For the following diagram, which resistor(s) controls the "SPACE:"

R1R2R1 + R2

22. The maximum frequency of operation for a 555 is:100kHz500kHz5MHz500Hz

23. For the following diagram, the Mark:Space ratio will be:

Greater than 50%Less than 50%EqualUnable to be determined

Output HIGH (mS)

Output LOW (mS)

Frequency (kHz)

Calculate the Frequency, HIGH-interval and LOW-intervalfor a 555 in ASTABLE mode. See answer below for Monostable (Delay):

Delay Sec

24. Use the calculator above to obtain the output frequency of thefollowing circuit:

0.0001412kHz141Hz141kHz

25. If the two resistors in Q24 are swapped, the output frequency will:IncreaseDecreaseRemain the same

26. What value resistors with a 100u, will produce a delay of 15 seconds?

100k plus 33k47k plus 47k22k plus 33k

27. What value of delay will 3M3 and 100u produce?:0.47 sec3.74 sec363 secs

28. Which set of values will produce the highest frequency:100k 22k 10n10k 4k7 100n22k 100k 10n4k7 10k 100n

29. Which set of values will produce the highest frequency:4k7 1k 1n2k2 1k 2n21k 1k 4n710k 1k 10n

30. Which set of values will produce the longest delay:3M3 47u1M 100u470k 220u

31 What type of circuit is shown in the diagram below:

MonostableAstableFree-Running

32. What is the name of the pin that activates a 555 in Delay mode:ControlTriggerDischargeThreshold

33. Identify the output waveform produced by the following circuit:

(a) (b) (c) (d) (e) (f)

34. Identify the output waveform produced by the following circuit:

(a) (b) (c) (d) (e) (f)

35. Identify the output waveform produced by the following circuit:

(a) (b) (c) (d) (e) (f)

36. If the trigger-pulse in Q34 is held LOW longer than the delayproduced by R and C, the output will:

Stay LOWStay HIGHGo LOW after the Delay and remain LOWGo LOW after the Delay for an instant, then go HIGH

37. Will the following circuit work?

YesNoA resistor must be connected between pin 2 and 0v railA resistor must be connected between pin 2 and the positive rail

38.

The circuit will settle with the LED onThe circuit will settle with the LED offThe circuit will oscillate at a high frequencyUnable to be determined

39.

The circuit will settle with the LED onThe circuit will settle with the LED offUnable to be determined

40.

The circuit will settle with the LED onThe circuit will settle with the LED offThe circuit will oscillateUnable to be determined

Final Assessment

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