Jenis2 lukisan elektronik

Seperti yang kita sedia maklum, lukisan merupakan karya seni seperti MONA LISA. Tetapi dalam elektronik industri, lukisan-lukisan tersebut dibahagikan kepada:

1. Lukisan blok/sistem

2. Lukisan litar

3. Lukisan pemasangan

4. Lukisan skematik

5. Lukisan litar tercetak

Berikut adalah contoh2 lukisan yang dimaksudkan.

Lukisan blokdigunakan untuk menerangkan secara ringkas dan mudah bagaimana fungsi serta operasi sesuatu unit dalam satu litar atay sistem.

 

Lukisan litar menunjukan keseluruhan fungsi sesuatu litar

Lukisan pemasangan digunakan untuk menggambarkan sambungan dan pemasangan sebenar bagi sesuatu litar dan kedudukan fizikal sesuatu komponen, pendawaian dan alatambah. 

Lukisan skematik adalah lebih kurang sama dengan lukisan litar, kelebihan lukisan skematik berbanding lukisan litar adalah ia dimuatkan dengan 'power rating', penyambungan tambahan dan lain2 lagi. Kebiasaannya ia dilengkapkan dengan maklumat2 pengujian.

Litar tercetak menggambarkan corak jalur pengalir dan kedudukan komponen (susunan) yang terdapat diatas PCB (printed circuit board)

PLC

The National Electrical Manufacturers Association (NEMA) defines a PLC as a "digitally operating electronic apparatus which uses a programmable memory for the internal storage of instructions by implementing specific functions, such as logic, sequencing, timing, counting, and arithmetic to control through digital or analog I/O modules various types of machines or processes."

To understand how PLC working, you need to understand the working principles of relay, a relay has a coil which is supplied by a voltage source and it is connected to two terminals.

The principle of the relay: while connected to voltage source then all contacts will change their status. NO means contacts ‘close’ and NC means contacts ‘open’.

The principle of PLC signal is the device input (on/off) will activate the coils. All inputs are reflecting each input device. (In this case, it is stored in a memory data input) coil will control all of these conditions on / off internal contacts that arranged in a program PLC / ladder diagram (programming & processing). 

SEMICONDUCTOR

Semiconductors have had a monumental impact on our society. You find semiconductors at the heart of microprocessor chips as well as transistors. Anything that's computerized or uses radio waves depends on semiconductors.

Today, most semiconductor chips and transistors are created with silicon. You may have heard expressions like "Silicon Valley" and the "silicon economy," and that's why -- silicon is the heart of any electronic device.

A diode is the simplest possible semiconductor device, and is therefore an excellent beginning point if you want to understand how semiconductors work. In this article, you'll learn what a semiconductor is, how doping works and how a diode can be created using semiconductors. But first, let's take a close look at silicon.

Silicon is a very common element -- for example, it is the main element in sand and quartz. If you look "silicon" up in the periodic table, you will find that it sits next to aluminum, below carbon and above germanium.

Silicon sits next to aluminum and below carbon in the periodic table.

Carbon, silicon and germanium (germanium, like silicon, is also a semiconductor) have a unique property in their electron structure -- each has four electrons in its outer orbital. This allows them to form nice crystals. The four electrons form perfect covalent bonds with four neighboring atoms, creating a lattice. In carbon, we know the crystalline form as diamond. In silicon, the crystalline form is a silvery, metallic-looking substance.

In a silicon lattice, all silicon atoms bond perfectly to four neighbors, leaving no free electrons to conduct electric current. This makes a silicon crystal an insulator rather than a conductor.

Metals tend to be good conductors of electricity because they usually have "free electrons" that can move easily between atoms, and electricity involves the flow of electrons. While silicon crystals look metallic, they are not, in fact, metals. All of the outer electrons in a silicon crystal are involved in perfect covalent bonds, so they can't move around. A pure silicon crystal is nearly an insulator -- very little electricity will flow through it. But you can change all this through a process called doping.

BASIC ELECTRICAL / ELECTRONIC LAWS (FORMULA)

Dalam litar elektronik/elektrik, pengguna rumus untuk mengira arus, voltan dan sebagainya adalah sangat penting untuk memastikan sesuatu litar boleh berfungsi dengan baik disamping boleh mengelakkan kerosakan komponen-komponen disebabkan 'overload' (tidak mengikut spesifikasi ('rating')).

Di bawah menunjukkan beberapa rumus yang asas untuk mengira arus, 

voltan dan rintangan litar (Arus terus (A.T): 

Hukum ohm's

Hukum ohm menytakan arus elektrik, I yang mengalir melalui suatu pengalir antara 2 titik yang lain berkadar terus dengan beza keupayaan, V antara kedua-dua titik, serta berkadar songsang dengan rintangan R.  

Hukum kirchoff (arus)

Di pertengahan abad 19 Gustav Robert Kirchoff (1824 – 1887) menemukan cara untuk menentukan arus listrik pada rangkaian bercabang yang kemudian di kenal dengan Hukum Kirchoff. Hukum ini berbunyi “ Jumlah kuat arus yang masuk dalam titik percabangan sama dengan jumlah kuat arus yang keluar dari titik percabangan”. Yang kemudian di kenal sebagai hukum Kirchoff I. Secara matematis dinyatakan

Bila digambarkan dalam bentuk rangkaian bercabang maka akan diperoleh sebagai berikut::

Hukum kirchoff (voltan)

Hukum Kirchoff secara keseluruhan ada 2, dalam sub ini akan dibahas tentang hukum kirchoff 2. Hukum  Kirchoff 2 dipakai untuk menentukan kuat arus yang mengalir pada rangkaian bercabang dalam keadaan tertutup (saklar dalam keadaan tertutup).
Perhatikan gambar berikut!
Hukum Kirchoff 2 berbunyi : ” Dalam rangkaian tertutup, Jumlah aljabbar GGL (E) dan jumlah penurunan potensial sama dengan nol”. Maksud dari jumlah penurunan potensial sama dengan nol adalah tidak ada energi listrik yang hilang dalam rangkaian tersebut, atau dalam arti semua energi listrik bisa digunakan atau diserap.
Dari gambar diatas kuat arus yang mengalir dapat ditentukan dengan menggunakan beberapa aturan sebagai berikut :

• Tentukan arah putaran arusnya untuk masing-masing loop.
• Arus yang searah dengan arah perumpamaan dianggap positif.
• Arus yang mengalir dari kutub negatif ke kutup positif di dalam elemen dianggap positif.
• Pada loop dari satu titik cabang ke titik cabang berikutnya kuat arusnya sama.
• Jika hasil perhitungan kuat arus positif maka arah perumpamaannya benar, bila negatif berarti arah arus berlawanan dengan arah pada perumpamaan.

 

RESISTOR COLOR CODE AND READING

Resistor is 1 of the most common electronic component in industry electronic, it used to limit current flow in a circuit, most electronic circuit consist of at least 1 resistor. Resistor come with a variety of physical size and resistance. In order to use the correct resistor, a technician should be able to read and calculate the resistance value. Below the the basic color reading of resistor and simple coding.

 

DIGITAL MULTIMETER

Introduction

A multimeter is used to make various electrical measurements, such as AC and DC voltage, AC and DC current, and resistance. It is called a multimeter because it combines the functions of a voltmeter, ammeter, and ohmmeter. Multimeters may also have other functions, such as diode and continuity tests.

Important note: The most common mistake when using a multimeter is not switching the test leads when switching between current sensing and any other type of sensing (voltage, resistance). It is critical that the test leads be in the proper jacks for the measurement you are making.

Safety Information

• Be sure the test leads and rotary switch are in the correct position for the desired measurement.
• Never use the meter if the meter or the test leads look damaged.
• Never measure resistance in a circuit when power is applied.
• Never touch the probes to a voltage source when a test lead is plugged into the 10 A or 300 mA input jack.
• To avoid damage or injury, never use the meter on circuits that exceed 4800 watts.
• Never apply more than the rated voltage between any input jack and earth ground (600 V for the Fluke 73).
• Be careful when working with voltages above 60 V DC or 30 V AC rms. Such voltages pose a shock hazard.
• Keep your fingers behind the finger guards on the test probes when making measurements.
• To avoid false readings, which could lead to possible electric shock or personal injury, replace the battery as soon as the battery indicator appears.

---

Input Jacks

The black lead is always plugged into the common terminal. The red lead is plugged into the 10 A jack when measuring currents greater than 300 mA, the 300 mA jack when measuring currents less than 300 mA, and the remaining jack (V-ohms-diode) for all other measurements.

---

Range

The meter defaults to autorange when first turned on. You can choose a manual range in V AC, V DC, A AC, and A DC by pressing the button in the middle of the rotary dial. To return to autorange, press the button for one second.

---

Automatic Touch Hold Mode

The Touch Hold mode automatically captures and displays stable readings. Press the button in the center of the dial for 2 seconds while turning the meter on. When the meter captures a new input, it beeps and a new reading is displayed. To manually force a new measurement to be held, press the center button. To exit the Touch Hold mode, turn the meter off. Note: stray voltages can produce a new reading.

Warning: To avoid electric shock, do not use the Touch Hold to determine if a circuit with high voltage is dead. The Touch Hold mode will not capture unstable or noisy readings.

---

AC and DC Voltage

---

Resistance

Turn off the power and discharge all capacitors. An external voltage across a component will give invalid resistance readings.

---

Diode Test

---

Continuity Test

This mode is used to check if two points are electrically connected. It is often used to verify connectors. If continuity exists (resistance less than 210 ohms), the beeper sounds continuously. The meter beeps twice if it is in the Touch Hold mode.

---

Current

Warning: To avoid injury, do not attempt a current measurement if the open circuit voltage is above the rated voltage of the meter. 
 
To avoid blowing an input fuse, use the 10 A jack until you are sure that the current is less than 300 mA.
Turn off power to the circuit. Break the circuit. (For circuits of more than 10 amps, use a current clamp.) Put the meter in series with the circuit as shown and turn power on.