555 IC Timer Question & Answers November 29, 2021 By WatElectronics This article lists 100 555 IC Timer MCQs for engineering students. All the 555 IC Timer Questions & Answers given below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up their fundamentals on 555 IC Timer. A 555 timer or 555 IC is an electronic chip designed by using IC technology. This timer was invented by "Hans R.Camenzind" in 1971. It comprises 8pins and is available in a dual inline package whose functional parts include a comparator, flip flop, and voltage divider. They are designed using passive components such as diodes, transistors, and op-amps and operate between 4.5 to 15V. The 555 timer provides a stable and precise delay of oscillation. They operate in 3 modes mono, astable, and bistable modes, where each of these modes has different states like stable and unstable. These states are switched from one state to another on the application of external triggers. 555ICs are employed in applications such as duty cycle, multi-vibrator, operating frequency, and pulse time. 555 timers benefit in terms of pulse generations, can be interfaced externally, and can adjust the time in seconds or milliseconds. But lack in terms of a narrow range, non-linear frequency modulation is observed, and abrupt temperature changes. 1.) Which of the following scientist invented 555 IC _____? Hans R.Camenzind Charles Richard James None Hint 2). Which of the following are the components of 555 times? Diodes Transistors Resistors All the above None Hint 3). _____ is the chip substance used in 555 timer during fabrication process? Silicon Platinum Diamond All the above None Hint 4). How many pins do a 555 timer consist of? 2 4 8 12 None Hint 5). Identify the IC package type of 555 timer? DIP QFP BGA CSP None Hint 6). Which of the following are the examples of timers? 555 556 559 All the above None Hint Read more about Timers. 7). Which of the following type of timer has 14 pins? 555 556 559 Both b and c None Hint 8). Which of the following is the temperature range of NE555 IC? 0 to 70 degrees Centigrade -70 to 70 degrees Centigrade -10 to 70 degrees Centigrade 10 to 70 degrees Centigrade None Hint 9). Which of the is the temperature range of SE555 IC? 0 to 70 degrees Centigrade -55 to +125 degrees Centigrade -10 to 70 degrees Centigrade 10 to 70 degrees Centigrade None Hint 10). Based on which of the following component used in 555 timer, the IC 555 is labeled? Resistors Capacitors Crystal All the above None Hint 11). Which of the following is the low power version of IC 555 timer? 7555 TLC555 765 Both a and b None Hint 12). A 555 timer chip is designed using __ technology? IC ASCII Silicon Chip Both a and c None Hint 13). Which of the following is the purpose of 555? Oscillators Pulse generators Timer circuits All the above None Hint Read more about Oscillators. 14). In which of the following applications do 555 IC produces delays? Flip flops Oscillators Voltmeters Both a and b None Hint 15). 555 timers operates in ___ number of modes? 2 3 4 5 None Hint 16). Which of the following is the function of a timer in electronics? Control device Monitoring device Measuring specific period All the above None Hint 17). Timers are classified into ___ types? 4 2 3 5 None Hint 18). A timer that counts from 0 is called_____? Up timer Down timer Stop-watch Both a and c None Hint 19). The pin 1 of 555 IC is ____? Ground Trigger Output Reset None Hint 20). The pin 2 of 555 IC is ____? Ground Trigger Output Reset None Hint 21). The pin 3 of 555 IC is ____? Ground Trigger Output Reset None Hint 22). The pin 4 of 555 IC is ____? Ground Trigger Output Reset None Hint 23). The pin 5 of 555 IC is ____? Control voltage Threshold Discharge Vcc None Hint 24). The pin 6 of 555 IC is ____? Control voltage Threshold Discharge Vcc None Hint 25). The pin 7 of 555 IC is ____? Control voltage Threshold Discharge Vcc None Hint 555 IC Timer Interview Questions and Answers 26). The pin 8 of 555 IC is ____? Control voltage Threshold Discharge Vcc None Hint 27). Which of the following should be the voltage on trigger pin of 555IC with respect to supply voltage? <1/3 >1/3 =1/3 1 None Hint 28). At what value output will be in an 555IC when output pin is low? near to +3V near to +5V near to +1V near to +0V None Hint 29). At what value output will be in an 555IC when output pin is high? near to +3V near to +5V near to +1V near to +0.5V None Hint 30). Which of the following components are connected to output pin of 555IC? Load Power supply Source Both a and b None Hint 31). Which of the following 555 IC pin is connected to supply? Reset Control voltage Threshold Discharge None Hint 32). Which of the following 555 IC pin is connected to ground? Reset Control voltage Threshold Discharge None Hint 33). Which of the following is the passive component is connected to control voltage pin in 555IC? Resistor Capacitor Inductor All the above None Hint 34). Which of the following component in 555IC avoids power voltage? Resistor Capacitor Inductor All the above None Hint 35). Which of the following pin in 555IC maintains value of capacitors voltage? Reset Control voltage Threshold Discharge None Hint 36). Which of the following are the components of 555 IC? Op-amps Flip-flops Transistor All the above None Hint 37). How many op-amps are used in 555IC? 2 3 4 5 None Hint 38). Which of the following type of flip-flop is used in 555IC? SR T D JK None Hint 39). A voltage driver in 555IC has ____ components? Resistors Capacitors Inductors All the above None Hint 40). Which of the following component is the input to SR flip flop? Resistor Comparators Resistors Capacitor None Hint Read more about Flip-Flops. 41). Which of the following is the input supply to 555IC? +5V to +18V 0.5V to 10V 1V to 5V 2V to 30V None Hint 42). Which of the following is the load current limit of 555IC? 100mA 200mA 300mA 400mA None Hint 43). A 555IC has ___ output value of current? Zero High Low Infinity None Hint 44). Which of the following is the value of temperature stability in a 555IC? 50ppm/degrees 100ppm/degrees 150ppm/degrees 200ppm/degrees None Hint 45). A 555IC has ___ quantity of power dissipation? Minimum Maximum Zero Infinity None Hint 46). Which of the following are the applications of 555IC? Duty cycle Operating frequency Pulse time All the above None Hint 47). Which of the following are the advantages of 555IC? Used in pulse generators Can be interfaced externally Can adjust time All the above None Hint 48). A multi-vibrator is implemented in ___ number of states? 2 3 4 5 None Hint 49). Multi-vibrators are of ____ types? 2 3 4 5 None Hint 50). Which of the following multi-vibrator is unstable and frequently switches from on-off? A-stable Mono-stable Bi-stable All the above None 555 IC Timer Important Questions for Interviews 51). Which of the following multi-vibrator has one un-stable and one stable state? A-stable Mono-stable Bi-stable All the above None Hint 52). Which of the following mode of multi-vibrator requires trigger to shift to other state? A-stable Mono-stable Bi-stable All the above None Hint 53). Which of the following mode of multi vibrator has dual stable states? A-stable Mono-stable Bi-stable All the above None Hint 54). A multi vibrator type circuit is also known as _________? Storage device Flip-flop Memory All the above None Hint 55). How many amplifying stages a astable multivibrator has? 1 2 3 4 None Hint 56). Which of the following type of feedback is given in As-stable type multi-vibrator? Negative Positive Both a and b Inverted None Hint 57). How many capacitive-resistance coupling based networks are used in As-stable type multivibrator? 1 2 3 4 None Hint 58). Which of the following are the amplifying elements used in Multi-vibrator? FET JFET Vacuum tubes All the above None Hint 59). How many transistors are on during operation of Multivibrator? 1 2 3 4 None Hint 60). On which of the following components do a as-stable multivibrator depends on? Transistor OP-amps Resistors Both a and b None Hint Read more about Op-amp. 61). What is the delay range of As-stable multivibrator? Ms to hours Hours Nano sec to ms All the above None Hint 62). Which of the following is the formula of time period of Astable multivibrator? Tcharges + Tdischarge Tcharges – Tdischarge Tcharges / Tdischarge T charges * T discharge None Hint 63). Which of the following is formula of Tcharge of Astable multivibrator? Astable Multivibrator 0.69(R1+R2) 0.5(R1+R2) 3(R1+R2) 4(R1+R2) None Hint 64). What is value of output of Astable multivibrator during charging period? High Low Zero Infinity None Hint 65). Which of the following is time period of Astable multivibrator during charging period? Astable Multivibrator 1.38sec 2sec 2.5sec 3sec None Hint 66). Which of the following is the discharge value of Astable multivibrator? Astable Multivibrator 0.69R2C1 0.969R2C1 0.4R2C1 0.169R2C1 None Hint 67). What is the value of output during discharge time of Astable multivibrator? High Low Zero Infinity None Hint 68). Which of the following is the oscillation frequency of Astable multivibrator? Astable Multivibrator 0.5 MHz 0.483 Hz 0.1MHz 0.2 GHz None Hint 69). Which of the following is the formula of duty cycle? Astable Multivibrator Ton/Toff Ton –Toff Toff –Ton Ton * Toff None Hint 70). Calculate the duty cycle of following Astable multivibrator? Astable Multivibrator 66% 65% 70% 75% None Hint 71). In astable multivibrator, when discharged based transistor is off then the capacitor ______? Charges Discharges Inactive All the above None Hint 72). Which of the following are the applications of Astable multivibrator? TV Analog IC’s Square wave generator All the above None Hint 73). Which of the following are the advantages of a Astable multivibrator? Minimum cost Simple in design Switches between states All the above None Hint 74). Which of the following are the disadvantages of Astable multivibrator? Incomplete transfer of output to input Signal obtained is too small Absence of complete closed loop All the above None Hint 75). Which of the following is the function of multivibrator? Processing Generating pulses Clamping Both a and b None Hint 555 IC Timer Quiz Questions and Answers. 76). A mono stable type multi vibrator generates output wave of ____ form? Linear Sine Square Rectangle None Hint 77). On which time constant do a mono stable multi vibrator depends on? RC R C LC None Hint 78). A monostable multi vibrator has ___ stability factor? High Low Medium Infinity None Hint 79). A mono stable multi vibrator generates ____ type of timing pulses? Abrupt Approx Accurate Both a and b None Hint 80). A unstable state of mono stable multi vibrator is also called as _____? Quasi stable state Determistic state Undetermistic state All the above None Hint 81). Based of which of the following factor the stable condition of a mono stable multi vibrator depends on? Capacitors charging Resistors used OP-amps direction All the above None Hint Read more about Capacitor. 82). Which of the following function in mono stable multi vibrator is responsible for change of states? Trigger Clock Voltage applied Both a and b None Hint 83). Which of the following are the components of mono stable multi vibrator? 555IC Resistors Capacitor All the above None Hint 84). Which of the following should be the amplitude value of mono stable multi vibrator? +2/3VCC +1/3VCC +1/4VCC >+2/3VCC None Hint 85). Which of the following are the applications of mono stable multi vibrator? PWM Capacitance measurements Pulse detectors All the above None Hint 86). Which of the following type of switches are used in bistable mode? Bounce free latched Bounce latched Latched All the above None Hint 87). A mono stable mode is also called as ______? One shot mode Flip flop mode Inverter mode Free running mode None Hint 88). A astable mode is also called as ______? One shot mode Flip flop mode Inverter mode Free running mode None Hint 89). A biastable mode is also called as ______? One shot mode Flip flop mode Inverter mode Free running mode None Hint 90). A Schmitt mode is also called as ______? One shot mode Flip flop mode Inverter mode Free running mode None Hint 91). Which of the following mode uses inverter? One shot mode Flip flop mode Schmitt mode Free running mode None Hint 92). Which of the following is the purpose of Inverter mode? Filters signal noise Amplifies signal Clips signal Clamps signal None Hint 93). Calculate the duty cycle of Astable mode when its frequency is 0.1Hz (+0.048%), C is 100 micro F, R1, R2 is 8.2Kohms and 68Kohms. 52.8 50.8 51.2 55.2 None Hint 94). Which of the following is units of capacitance? Farads Henry Ohms Joules None Hint 95). Which of the following is the formula for astable modes, high time interval of single pulse? t high = ln(2) (R1+R2) C t high = ln(2) R2 C t high = ln(2) (R1-R2) C t high = ln(2) /(R1+R2) C None Hint 96). Which of the following is the formula for astable modes, low time interval of single pulse? t high = ln(2) (R1+R2) C t high = ln(2) R2 C t high = ln(2) (R1-R2) C t high = ln(2) /(R1+R2) C None Hint 97). Which of the following is the formula for duty cycle? {t(high)/[t(high) + t (low)] }* 100% {t(high) * [t(high) + t (low)] }* 100% {t(high)* [t(high) + t (low)] } / 100% {t(high)/[t(high) - t (low)] }* 100% None Hint 98). Timers are generally built using _______? Mechanical Electronic Electromechanical All the above None Hint 99). Which of the following is the time constant of monostable multivibrator? t = 1.1 R1 * C1 t = 1.1 R1 / C1 t = 1.1 R1 + C1 t = 1.1 R1 - C1 None Hint 100). Which of the following are the advantages of IC technology? Performance Area Low cost All the above None Hint Time's up
