Electrical Measurements & Measuring Instruments Multiple Choice Questions on “Ramp Type DVM”.
1. Ramp type DVM uses ___________
a) a linear ramp technique
b) a non-linear ramp technique
c) an exponential ramp technique
d) an asymptotic ramp technique
Answer: a
Clarification: A ramp type DVM makes use of a staircase ramp technique or a linear ramp technique. Compared to the linear ramp technique, the staircase ramp technique is much simpler.
2. Linear ramp technique is based on __________
a) voltage measurement
b) time measurement
c) current measurement
d) resistance measurement
Answer: b
Clarification: Linear ramp technique works on the principle of measurement of time required by a linear ramp to rise from 0 V to the input voltage. It can also be the time required by the input voltage to fall to 0 V.
3. Time is measured using __________
a) clock
b) logic gates
c) counter
d) flip-flops
Answer: c
Clarification: An electronic counter is used for the measurement of time in the linear ramp technique. A digital display is used to show the numerical value of time.
4. Which is the main device used in the linear ramp technique?
a) exponential ramp
b) asymptotic ramp
c) non-linear ramp
d) linear ramp
Answer: d
Clarification: The linear ramp technique essentially consists of a linear ramp. It is either positive or negative going. Range of the linear ramp varies from –12 V to +12 V. Base range varies from –10 V to +10 V.
5. Resolution depends on __________
a) frequency
b) resistance
c) voltage
d) current
Answer: a
Clarification: In the linear ramp technique, resolution is dependent on the frequency of the local oscillator. By adjusting the frequency of the local oscillator the resolution of the linear ramp can be made higher.
6. How is input voltage measured?
a) by using a voltmeter
b) by counting the pulses
c) by using a multimeter
d) by using a transformer
Answer: b
Clarification: The electronic counter used in the linear ramp technique counts the definite number of pulses during the start and end pulse. This count is a measure of the input voltage signal.
7. Which determines the rate of measurement cycles?
a) oscillator
b) amplifier
c) mutivibrator
d) oscilloscope
Answer: c
Clarification: Initiation of the measurement cycles is taken care of by the sample rate multivibrator. This vibrator oscillates at the rate of 1000 cycles per second. It is adjusted by a front panel control.
8. What is the typical value of the multivibrator?
a) 10 cycles/second
b) 0.2 cycles/second
c) 50 cycles/second
d) 5 cycles/second
Answer: d
Clarification: A multivibrator has a typical value of 5 cycles/second. It has an accuracy of the order of ±0.005 %. The ramp generator starts the next ramp voltage based on the sample rate.
9. Swing of the ramp is __________
a) ±12 V
b) ±10 V
c) ±8 V
d) ±5 V
Answer: a
Clarification: In the linear ramp technique, a swing of ±12 V is produced by the ramp. This limits the effective voltage available to ±10 V considering the voltage drop across the components in the circuit.
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