Thursday 30 July 2020
Wednesday 29 July 2020
Monday 27 July 2020
A Bipolar Transistor
In the Diode articles we saw that simple diodes are made up from two pieces of semiconductor material, either silicon or germanium to form a simple PN-junction and we also learnt about their properties and characteristics. If we now join together two individual signal diodes back-to-back, this will give us two PN Junction connected together in series that share a common P or N terminal. The fusion of these two diodes produces a three layer, two junction, three terminal device forming the basis of a Bipolar Junction Transistor, or BJT for short.
Transistors are three terminal active devices made from different semiconductor materials that can act as either an insulator or a conductor by the application of a small signal voltage. The transistor’s ability to change between these two states enables it to
Sunday 26 July 2020
What is Microswitch and how it works ?
What is Microswitch and how it works ?
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3-phase Motor windings connections - Lecture
3-phase Motor windings connections - Lecture
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Saturday 25 July 2020
Monday 20 July 2020
Sunday 19 July 2020
Saturday 18 July 2020
Will robots replace humans ?
I talked a lot with my friends about this future, where robots will replace humans and we all be unemployed. Most of them told me that is not possible, but I am quite sure that one day this will be real.
I also want to believe that this will not make people poor, but on the contrary, people will thrive. I imagine a day when a robot will replace 3 human workers, but all of these workers will be represented by this robots, therefore they will receive a certain wage. Why would the companies replace all the human workers with robots if nobody will have money to use the services they provide or consume the products they produce?!
Anyways, I wouldn’t like to be replaced by a robot and become a useless “thing” trying to survive everyday without money. Probably, if that day will come, I would probably like to have a piece of land to ensure my basic needs.
PN Junction
When the N-type semiconductor and P-type semiconductor materials are first joined together a very large density gradient exists between both sides of the PN junction. The result is that some of the free electrons from the donor impurity atoms begin to migrate across this newly formed junction to fill up the holes in the P-type material producing negative ions.
However, because the electrons have moved across the PN junction from the N-type silicon to the P-type silicon, they leave behind positively charged donor ions (ND) on the negative side and
Cloud Computing
Grid computing, in its practical form, represents the concept of connecting two or more spatially and administratively diverse clusters or supercomputers together in a federating manner. The term ”the Grid" was coined in the mid 1990's to represent a large distributed systems infrastructure for advanced scientific and engineering computing problems. Grids aim to enable applications to harness the full potential of resources through coordinated and controlled resource sharing by scalable virtual organizations. While not all of these concepts carry over to the Cloud, the control, federation, and dynamic sharing of resources is conceptually the same as in the Grid. This is outlined as Grids and Clouds are compared at an abstract level and many concepts are remarkably similar. From a scientic perspective, the goals of Clouds and Grids are also similar. Both systems attempt to provide large amounts of computing power by leveraging a multitude of sites running diverse applications concurrently in symphony. The only significant differences between Grids and Clouds exist in the implementation details, and the reproductions of them, as outlined later in this section.
The other major component,Web 2.0, is also a relatively new concept in
Discrimination between residual current circuit breakers (RCCBs)
Generalities and discrimination between RCDs
The
operating principle of the residual current release is basically the
detection of an earth fault current, by means of a toroid transformer
which embraces all the live conductors, included the neutral if
distributed.
In absence of an earth fault, the vectorial sum of the currents IΔ is equal to zero.
In case of an earth fault, if the IΔ value exceeds the rated residual operating current IΔn, the circuit at the secondary side of the toroid sends a command signal to a dedicated opening coil causing the tripping of the circuit-breaker.
Figure 1 – Operating principle of the residual current device
Classifications of RCDs
A first classification of RCDs can be made according to the type of the fault current they can detect:
- AC type: the tripping is ensured for residual sinusoidal alternating currents, whether suddenly applied or slowly rising;
- A type: tripping is ensured for
PID Controller - Closed Loop Position Control
Friday 17 July 2020
How works a 1-Phase Motor Direct Online Starter (DOL) ?
In this post I want to explain you how Direct Online Starter (DOL) circuit for 1-Phase Motor works.
For smaller motors a starting current is not too large, so DOL stater can be use safely.
It is very popular and often use circuit for starting a small motors.Look
what we have on this circuit
- Terminal block X1 for connect power supply to the circbuit
- MCB F1 is used as main power On / Off switch and also as a motor protection.
- A electromagnetic contactor K1 is used to turn on and off a power to the motor M.
- 1-Phase motor M
- This is a power part of the circuit.
- Then we have an elements of control part of the circuit:
- Exactly we use a main contacts of contactor K1 for it .
- The contactor K1 has also one auxiliary normal open contact (terminals 13 and 14)
- Here we have a coil of contactor K1.
- In a circuit we have two push buttons S1 and S2.
- Push button S1 is use for stop the motor, and it is normal close NC.
- Push button S2 is use for start a motor, and it is normal open NO.
Now, how this all works ?
When we turn on a circuit breaker F1 we put a voltage on main contacts of contactor K1 and on a push button S1. Because button S1 is normal close type, we have a voltage on on terminals 13 of button S2 and auxiliary contact K1.
In this state DOL starter is ready to switch a motor.
So now if we push button S2, we give a voltage on contactor's coil K1. Main contacts K1 get close, and a motor M get start. In a same time auxiliary contact K1 will also get close, so when we release start bush button S2, coil K1 will be energized by this contact, and motor will stay in run state.
When we press Start button S2 current path for contactor's coil K1 is closed from L terminal of terminal block X1 through circuit breaker F1, button S1, button S2, coil K1 and terminal N.
Then when we release a Start button S2 all is same, but now current is flow through closed auxiliary contact K1 instead of through S2 button. In that way auxiliary contact K1 keeps a coil K1 energized. This contact is known as holding contact as it keeps contactor hold on.
Now when we press Stop button S1, we will break this path, coil K1 will be stop energized, main contacts, and auxiliary contact K1 get back to open position, and the motor stops.
Same effect will be when it will be make by open circuit breaker F1. It can happen in case of motor overload or if some short-circuit occur in a circuit.
We can use the circuit breaker F1 also for cut off a power from the circuit for some maintenance work.
When circuit breaker F1 is Off we also can not turn off a motor.
When circuit breaker F1 is ON our Direct Motor Starter is ready to work, and we can run the motor by press Start button S2.
Thursday 16 July 2020
Wednesday 15 July 2020
Digital Electronics - Basic Logic Gates
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Digital Electronics - Basic Logic Gates
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Monday 13 July 2020
Saturday 11 July 2020
Thursday 9 July 2020
World’s longest subsea power cable
The Guardian writes:
By 2023, the high-voltage, direct-current link will transmit the equivalent of enough electricity to power 1.5 million British homes between Bicker Fen in Lincolnshire and the South Jutland region in Denmark.
The Viking Link will be longer than the 450-mile North Sea link, which will import hydropower from Norway to the UK from 2021.
And the subsea power cable system works both ways: When the UK generates too much green power, it will be exported via the subsea power cables to its partner countries, and vice versa.
The UK currently has about 5GW of power cable capacity that connects the UK’s electricity system to power in France, the Netherlands, and the Republic of Ireland. By 2025, this capacity is expected to rise to 25GW. The UK will also connect to Germany and Belgium.
Wednesday 1 July 2020
Automated Old Bell - ATtiny13
Solution stops impatient people from holding down on the bell, and ringing it continuously or pressing it repeatedly.
After a press the bell rings 3 times, then stops ringing and cannot be rung again for 5 seconds.
