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Electronics Engineering
Electronics Engineering is a branch of engineering that deals with practical applications of electronic components, devices, systems, or equipment. Electronics are devices that operate on low voltage sources, as in electron tubes, transistors, integrated circuits, and printed circuit boards and use electricity as part of its driving force.
24,372 Questions
Explain the origin of finite output resistance of MOSFET devices?
let the mosfet be biased in saturation regior.
thus drain current in independent of drain to sourse voltage,
the VI chara. is a curve, when this is extended till X axis at pt. Vds=-Va
this is similar to effect in transistor
the o/p resistance is slope of V-I chara.. it should ideally be infinite, but has some finite value due to "CHANNEL LENGTH MODULATION"
Where are transient voltage most dangerous?
when reading voltage at the meter base where power comes in the house.
Is there any application where center tap rectifier is preferred over bridge rectifier?
For a center tapped full wave rectifier transformer secondary gives a voltage that is 2Vm. For a bridge rectifier it is Vm.
What are the voltages in secondary transmission electric lines?
A: Those voltages are called distribution voltages to differentiate from transmission voltages. And that varies from state to state and locals . Usually around 10kv to 20 kv
Why does vcc voltage called vcc?
I believe that Vcc stands for Voltage Common Collector. This is because the voltage is hooked up to the collector of the transistor.
Can you measure a vacuum tube using ohmmeter?
Maybe, but not sure info would be useful.
You can use ohmmeter to check that a tube's filament is intact.
Broken/burned-out filament is most likely reason for dead tube.
What can you substitute a logarithmic potmeter with?
I would simply suggest taking a linear potmeter of approx a value 700% higher. Then connect a resistor of the original value +20% (approx) across linear pot middle and either side. This makes it working almost like the original logaritmic potmeter. If you want reverse log or dual log, then just connect the resistor to the other leg from middle, or halve the resistor value and connect both from the middle and to each side.
If you are unsure how it works, then a spreadsheet provides you with abilities to simulate how it will work.
Example of a "Linear Log Pot":
A project I started on needed a reverse log taper of 10 K.
This was nowhere to be found and I thought, lets cheat.
I started with spreadsheet and put in a few formulas for parallell connection of resistors.
I found that a 68K linear and a 12K resistor in parallell would give much the same performance curve as a logaritmic taper.
It gives approx the same resistance and approx the same voltage (if used as a voltage divider) as a Log and reverse log taper.
we use the inductor because it helps the circuit to have an appropriate amount of current, so that the circuit in the appliance will say longer.
Why high resistances are not used in wheatstone bridge?
Because if high resistance is like kilo mega ohm is used , corresponding current through the balanced point is in the order of micro ampere, so you have to use micro ampere sensitive ammeter , otherwise normal ammeter always show zero reading
What type of material is used as contact material in switches?
Copper is used as a substrate of the contact meterial; on the grounds of cost; but the actual contacts themselves may be made of silver. Silver does not corrode a badly as copper, and a well designed switch will have a 'wiping' action in its operation, for this prolongs the life of the contacts.
In corrosive atmospheres, such as Rotorua, New Zealand, there is a quantity of H2S in the atmosphere, and platinum contacts are often used.
An Air Conditioning (ac) register is the little grille in the ceiling where conditioned air comes into a room.
What is the principle of operation of LDR?
Working of light dependent resistor
This circuit explains the principle of operation of LDR (light dependence resistor). The circuit has various applications like shadow alarm, automatic night/morning lamp.
LDR, an acronym for light dependent resistor is a resistor whose resistance is dependent on light. The resistance of LDR is of the order of Mega Ohms in the absence of light and reduces to a few ohms in presence of light. In this circuit when the light falls on LDR, the resistance of LDR becomes low and the entire voltage drop takes place across the variable resistance VR1 (10K). As a result the base of transistor (T1) gets high input and it gets biased thereby glowing the LED. When no light falls on LDR, the resistance of LDR becomes high so almost entire voltage drop takes place across it and the base of transistor is at low potential. So transistor does not gets biased nor it becomes conducting, hence switching off the LED. The sensitivity of the circuit can be adjusted by varying the preset VR1.
LDR, an acronym for light dependent resistor is a resistor whose resistance is dependent on light. The resistance of LDR is of the order of Mega Ohms in the absence of light and reduces to a few ohms in presence of light. In this circuit when the light falls on LDR, the resistance of LDR becomes low and the entire voltage drop takes place across the variable resistance VR1 (10K). As a result the base of transistor (T1) gets high input and it gets biased thereby glowing the LED. When no light falls on LDR, the resistance of LDR becomes high so almost entire voltage drop takes place across it and the base of transistor is at low potential. So transistor does not gets biased nor it becomes conducting, hence switching off the LED. The sensitivity of the circuit can be adjusted by varying the preset VR1.
What is reverse breakover voltage in scr?
That depends, you should look it up in the datasheet. For some thyristors it's as low as 6V
My dazzle says theres no input signal?
i had this problem maybe you should just check your wires or buy new or just buy new cap
Why Q symbol is used in transistor?
Transistors on schematics are labeled Q followed by a reference number because of tradition. The letter could be something else, for example I have some old schematics that use T, however T is traditionally used for transformers.
Some other traditional schematic component labels are:
- R, resistor
- C, capacitor
- L, inductor/coil
- V, vacuum tube
- U or IC, integrated circuit
- D or CR, semiconductor diode
- Z, zener diode
- M, meter or motor
- ANT, antenna
- CB, circuit breaker
- F, fuse
- RT, thermistor
- J, female connector/socket
- P, male connector/plug
- Y, crystal
- E or G, ground
- S or SW, switch
- K, relay or contactor
- B or BT, battery
- PS, power supply
- NE, neon lamp
- DS, display or lamp
Is transistor a linear or non linear device?
we will operate transistor mainly in 4 regions..namely active ,cutoff,saturation and pinch off region depending on the type of biasing.
if it is under active region then transistor is a linear device..
linearity in the sense if the output is proportional to input then it is said to be linear.
How does a capacitor act as a filter?
The cutoff frequency of filter depends upon the value of capacitor and resistance. Therefore, below cutoff frequency or above this frequency, capacitor allow to pass all other frequencies.
What is transistor and how can it operate and what are its types?
A transistor is a semiconductor device used to amplify & switch electronic signals. The name transistor comes from the 'trans' of transmitter and 'sister' of resistor. Transistors are used in a wide array of electronic equipment, ranging from pocket calculators and radios to industrial robots and communications satellites.
There are two types of transistor viz:
- Primary type transistor-The primary type of transistor in use is known as a bipolar junction transistor, which consists of three layers of semi-conductor material, two of which have extra electrons, and one which has gaps in it. The two with extra electrons (N-Type) sandwich the one with gaps (P-Type). These bipolar transistor are divided into NPN and PNP types. All these primary type of transistor are shielded to protect from light source if it is not shielded from light then the light may be used to open or close the gate, in which case it is referred to as a phototransistor, functioning as a highly-sensitive photodiode.
- Secondary type transistor-The secondary type of transistor is known as a field-effect transistor, and consists either entire of N-Type semi-conductive material or P-Type semi-conductive material, with the current controlled by the amount of voltage applied to the transistor.
General process of Transistor Working
Each transistor has a store of electrical charge that remains there until it is turned on. In order to turn on a transistor, a small electrical charge needs to enter it via the base. When this happens, the electrical charge opens up the collector, and a more powerful charge leaves through the emitter. Electrical charge is measured in milliamps, and the typical transistor will multiply an electrical charge by one hundred times the number of milliamps it has. The electrical charge that is emitted by a transistor will then flow through a route designated by however the component it is attached to is designed. Complex electronics have many paths that electrical currents need to travel on, and therefore many transistors will be needed in order to constantly supply enough power to work the device.
There's no such phenomena as negative DC.
Minus sign only means, that current is flowing the other way than you are measuring.
It's danger is exactly the same as "positive" DC.
That depends on the particular radar system.
A simple speed radar used by law enforcement can simply be held and pointed at a target to determine the speed of the target.
A more complex system like an air traffic control radar system would have display consoles for the radar operator to view the data.
What do you Mean dual tracking power supply?
It's a power supply with a positive and negative voltage, where one of the voltages tracks the other. For example: the negative voltage tracks the positive. If you regulate the positive to 15v, the negative is going to be -15v. This allows very precise symmetric power.
What is masking corresponding with IC fabrication?
Masking is an important process in IC fabrication that is used at every step whether its doping, oxidization, metallization, passivization, etc.
Masking at its simplest is done as follows:
- coat the wafer surface with a photosensitive plastic resin
- let the plastic resin set (sometimes mild heating assists this step)
- expose the plastic resin to light through a photomask
- develop the plastic resin with a chemical that dissolves away the unwanted parts (the undissolved parts of the plastic resin form the mask)
- perform the desired fabrication step
- remove the plastic resin with another chemical to give a clean wafer surface
The presence of the plastic resin prevents the given fabrication step from affecting that area of the wafer surface while the absence of the plastic resin allows the given fabrication step to affect that area of the wafer surface.
In certain fabrication steps the plastic resin would not be a satisfactory mask itself (e.g. steps performed in a furnace). For these steps a layer of silicon dioxide or silicon nitride is grown on the wafer surface and the masking with the plastic resin is used to etch away the silicon dioxide or silicon nitride which is then used as the mask to complete the difficult fabrication step. The silicon dioxide or silicon nitride layer is then removed.
A similar masking process is used in etching printed circuit boards.
The first known historical examples of masking being used was by metal engravers, who would take the piece of metal to be engraved and paint it with tar. When the tar set they would draw the pattern to be engraved on the tar with sharp tools, exposing bare metal in the scratches. The tar covered metal object was then immersed in a strong acid for a period of time. When removed from the acid the tar would be cleaned off, leaving an acid engraving.
