1.What are the differences between voltage and current
controlled devices?
Ans-In any (electronic) device controlling parameter is
current it is called current controlled device. eg bilpolar transistor- output
current is a function of base current.
In any (electronic) device controlling parameter is voltage
it is called voltage controlled device. eg Field effect transistor- output
current is a function of gate voltage.
It depends on the inherent physical mechanism which defines
the primary (independent) controlling parameter.
2- What is the difference between Power Amplifier and
Voltage Amplifier?
Ans-Power amplifiers basically amplify both current and
voltage (p=v*i). Voltage amplifiers only amplify the voltage.
In power amplifier feedback employed is current feedback and
In voltage amplifier voltage feedback is employed.
3- why the bjt is known as current controlled device
and fet is known as voltage controlled device ?
Ans- 1. In BJT because of the current the output will vary.
2. Where as in FET
by means of Voltage the output is varied.
4-What is the difference between DCS & PLC & SCADA ?
Ans-PLC stands for Programmable Logic ControllerDCS for Data
control SystemSCADA for Supervisory Control And Data Acquisition SCADA involves
supervision by a user in most cases the plant controller.Whereas PLC is the
means by which he performs the function of SCADA.DCS on the other hand stand
only to control the system and not to log any datain the process of
controlling.DCS controllers are faster than PLCs In DCS controller we can
adjust the scan time DCS are costly more inputs and outputs are there for DCS and
SCADA does not have a dedicated controller. In a DCS system there is
SCADA ystem already in it but for PLC sydtem addition all SCADA
software must be provided.
5-What is the difference between Silicon Controlled Switch
(SCS) and Gate Turn-off Switch (GTO)?
Ans-scs is nothing but it is the silicon controlled switch
as an SCR but gate turn off is that in which one of the turnoff method of SCR
6-What is the difference between emulator and simulator?
Ans-Simulator: A software program impersonating a Hardware.
Thus SIMULATING the scenarios faced in the original hardware.
Emulator: A Hardware (with or without software)
impersonating another Hardware. Thus ELIMINATING the need for the original.
7- What is the difference between Circuit Switching and Packet
Switching?Ans-Circuit switching is the transmission technology that has been
used since the first communication networks in the nineteenth century. In
circuit switching, a caller must first establish a connection to a callee
before any communication is possible. During the connection
establishment, resources are allocated between the caller and the
callee.
packet switching is a more recent technology than circuit
switching which addresses a disadvantage of circuit switching: the need to
allocate resources for a circuit, thus incurring link capacity wastes when no
data flows on a circuit. Packet switching introduces the idea of cutting data
on a flow into packets which are transmitted over
a network without any resource being
allocated.
8- the number of columns in a state table for
a sequential circuit with m flip-flops and n inputs is.
Ans-Its 2m+2n because.. If there are m flip-flops
there should be 2m nodes. If there are n inputs then each node will have 2n.
Q-Design a digital circuit which has one input two output
and one select line input should be 1000khz output should be 500khz and 250Khz
select line either 0 or 1
if 0 select 250khz
if 1 select 500khz
Ans-demux is the circuit which satisfies the given
requirement if 0 is given to the selectline 250khz o/p is provided else 500khz
o/p is provided.
9- What are digital elctronic flip flops, State the
different types of flip flop and their uses.
Ans-Digital electronic flip flops are temporary single bit
storage devices. Different types of flip flops are JK f/f RS f/f T F/F D f/f
this flip flops are using as storage device delay purpose as counter for
toggled as shift register etc
10- What is the difference between latches and flip flop ?
Ans-Latche is a bistable circuit which responds to change of
logic level as they occur. It has no external inputs.
Flip flop is a basic element of memory. It stores a single
bit. It has a multiple input.
Latches are level sensitive devices where
as Flipflops are edge sensitive device so it is said that latches
are level triggered and flip flop is edge triggered.
11-What is the Tri State of a Signal?
Ans-In digital ciruit the gate output can be only high or
low. In highstate the output source current at a minimum voltage greater than
~2.8V if load(fan out ) is proper. In low state it will sink current at max
output voltage less than ~0.8V.
Some times it is desirable to have a state output both not
high or low. with neither sinking or sourcing (with high output impedance).
This is called tristate. Tristate output cannot change output condition of
succeding logic gates unless tristate is disabled.
12- what is the main difference between 8085 and 8086
processors?
Ans-8085 is a 8 bit microprocessor,having 16-bit address
bus.8086 is a 16-bit microprocessor having 20-bit address bus.
Q- What is a sequential circuit and What is a
combinational circuit? Is there any difference between them? If yes what is it?
Ans-Combinational circuit are those whose output depends
only upon the present inputs but in sequential circuit the output depends upon
both present and past inputs. that is the difference
Combinational circuit does not have any memory in the
feedback path but the sequential circuit has memory in the feedback path.
Ex of SEQ Circuit: Encoder Decoder etc
Ex of Comb Circuit; Flipflop
13. What is the difference between
masking and non-masking?
Ans-In 8085 processor TRAP is a non maskable interrupt.
Whereas RST 7.5 6.5 5.5 intr are maskable interrupts.
Maskable means this interrupts can be left without
considering during the execution of the program.
Non maskable depicts that it has to be taken into account
during the execution of the program
14. What is difference between
Fixed-Bias Circuit & Self-Bias Circuit?
Ans-Fixed bias circuits get their bias voltages from
independently designed reference voltage sources (or even something as simple
as a voltage divider). Often is the case that the bias may be left for the
end-user to give some control over the operation point of the
circuit.
Self biased circuits get their bias voltages from the
circuit itself often in the form of a negative feedback. This is very useful
when a circuit is extremely sensitive to bias points and it becomes impractical
to provide external biases that are correct to very high accuracies. This can
happen in high gain amplifiers with very high impedance output nodes such as a
common source amplifier with an active load. The operation of the circuit
dependson the bias of the active load. It would therefore be desirable to
sacrifice some of this gain by providing a negative feedback from the output to
the gate of the active load. This way you wont have to bias the circuit
yourself but will lose some of the gain of the circuit as a price.
15. What is meant by filter? What are
the different types of filters?
Ans-Filters are the components of a circuit which remove distortion
or ripples.Types of filters :
1. High pass filters
2. Low pass filters
3. Band pass filters
16. what is meant by virtual ground in the op amp
?
Ans-Ideally the output of op-amp should be zero. So for this
to happen the 2 inputs must be same. Hence one of the input is considered to be
low or at ground potential. But this input is not actually ground hence it is
called as virtual ground.
17. What is meant by saying at what
current is transistor biased?
Ans-Bias current of a transistor is the preset DC current
when no input voltage signal is applied to it.
18. What is Race Around Condition in
a JK FlipFlop?
Ans-IN J-K FF , The clock time is higher than the output
toggling time then for J=1 & K=1 , the output will be changed irrelavent of
our input. This condition is known as "RACE AROUND CONDITION"..
19. How to Convert Binary to Excess 3
Code and vice versa?
Ans-A number i binary can be converted to excess-3 just by
adding the binary equivalent of 3 to the binary number.similarly a number in
excess-3 can be converted to binary just by subtracting the binary equivaent of
3 from the binary number.
20. How to convert Binary to Gray
Code
Ans-Take XOR of binary no. starting from right with the next
bit. Add 0 as leftmost bit to get answer eg. Â 111=7
gray code 0 xor 1,1 xor 1, 1 xor 1 i.e. 100 ans.
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