Friday, 8 September 2017


By Ask Biomedical

Interview questions and answers

The probability that a device will perform within its specifications for the number of

operations or time period specified.


The closeness of repeated samples under exact operating conditions.


The similarity of one measurement to another over time, where the operating

conditions have varied within the time span, but the input is restored.


The smallest interval that can be identified as a measurement varies.

The frequency of oscillation that is maintained due to the natural dynamics of the



Defines the behaviour over time of the output as a function of the input. The output

is the response or effect, with the input usually noted as the cause.

*Self Heating*

The internal heating caused within a device due to the electrical excitation. Self-

heating is primarily due to the current draw and not the voltage applied, and is

typically shown by the voltage drop as a result of power (I2

R) losses.


This defines how much the output changes, for a specified change in the input to the


Used in closed loop control, the setpoint is the ideal process variable. It is

represented in the units of the process variable and is used by the controller to

determine the output to the process.

*Span Adjustment*
The difference between the maximum and minimum range values. When provided

in an instrument, this changes the slope of the input-output curve.

*Steady state*

Used in closed loop control where the process no longer oscillates or changes and settles at some defined value.

Shortened form of static friction, and defined as resistance to motion. More

important is the force required (electrical or mechanical) to overcome such a


This is a measure of the force required to cause a deflection of an elastic object.

*Thermal shock*
An abrupt temperature change applied to an object or device.

*Time constant*

Typically a unit of measure which defines the response of a device or system. The

time constant of a first order system is defined as the time taken for the output to

reach 63.2% of the total change, when subjected to a step input change.

An element or device that converts information from one form (usually physical,

such as temperature or pressure) and converts it to another ( usually electrical, such

as volts or millivolts or resistance change). A transducer can be considered to

comprise a sensor at the front end (at the process) and a transmitter.


A sudden change in a variable which is neither a controlled response nor long


A device that converts from one form of energy to another. Usually from electrical

to electrical for the purpose of signal integrity for transmission over longer distances

and for suitability with control equipment.

Generally, this is some quantity of the system or process. The two main types of variables that exist in the system are the measured variable and the controlled

variable. The measured variable is the measured quantity and is also referred to as

the process variable as it measures process information. The controlled variable is

the controller output which controls the process.

This is the periodic motion (mechanical) or oscillation of an object.

*Zero adjustment*
The zero in an instrument is the output provided when no, or zero input is applied.

The zero adjustment produces a parallel shift in the input-output curve.

07)What do you mean by a voltage to frequency converter?

A device which convert an analog voltage into a pulse signal which frequency is proportional to the applied input voltage.

08)what is the function of frequency to voltage converter?*

A device which convert the frequency of the input signal into an proportional output voltage.

09)what are main application of frequency to voltage converter?*. 

The main applications of these are follows-

1. It is used to control the speed of motor.

2. It is used for rotational measurement.

3. It is used for digital to analog conversion.

10)Explain the Timer IC-555?*

IC-555 is timer IC which is used in a stable, multivibrator, square wave generator, triangular wave generator, pulse modulator and pulse detector circuit.

11)Explain the main feature of IC-723.

The main feature of IC-723 are-

1. Input voltage ( 9.5 Volt-40 volt)

2. Regulated output voltage (2 to 37 v)

3. Maximum load current = 150 ma.

4. Internal power dissipation is 800 mvolt.

12)what is function of pulse width modulator?*

In pulse width modulator the width of the output pulse is varying according to the variation in the amplitude of modulating signal


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