Transimpedance Amplifier

What is a Transimpedance Amplifier?

A Transimpedance Amplifier, or TIA for short, is an electronic amplifier circuit who’s job is to convert an input current source into a proportional output voltage. That is the transimpedance amplifier operates as a current-to-voltage converter (I-V converter).

The previous operational amplifier circuits have all used voltage as their primary input signal. But many active (self-generating) sensors like photodiodes (in photovoltaic mode) generate a current, not a voltage, in response to some external or environmental change.

Then we need to be able to convert this self-generated current into a voltage and the transimpedance amplifier allows us to do just that.

Converting Current Into A Voltage Drop

Ohm’s Law tells us that when an electric current (I) flows through a simple fixed resistor (R), a voltage (V) is developed or dropped across it with Ohm’s law taking the simple form of: V = I x R.

Because this Ohm’s Law relationship is linear, the voltage developed across the resistor is directly proportional and linear to the current flowing through it as shown by this 10Ω graph.

Therefore if we change the value of the current, the I*R voltage drop across the resistor proportionally changes by the exact same factor.

Note that this strict proportionality only holds true as long as the resistance, (R) remains constant and is actively flowing. Thus resistors are Ohmic devices.

However, the problem with different Types of Resistors is that they can quickly heat up. This is due to their I²R power loss if too much current passes through them causing them to change their resistance. Then the voltage drop will begin to change and the I-V relationship will lose its property of proportionality and therefore become non-linear.

Thus, using a single fixed resistor as our current-to-voltage device, can create various issues. Since if a large value resistor is used it presents a large input impedance to a particular circuit when we really want our current-to-voltage converter to have a low (near zero) input impedance for maximum signal transfer.

One way around this heat loss problem is to use an Inverting Operational Amplifier which allows us to control both the input impedance and output impedance of the circuit creating a much improved current-to-voltage converter.

The Transimpedance Amplifier

Transimpedance Amplifiers allows the current at one place in the circuit to become a voltage source elsewhere in the same circuit, rather than having the voltage drop affect of a resistor. This makes the amplifier circuit useful in converting a current to a voltage drop.

But how does a transimpedance amplifier work, and why do we need to build an amplifier circuit to accomplish the same thing as a fixed resistor?

From Inverting Amp to Transimpedance Amp

The basic op-amp transimpedance amplifier can be constructed using an inverting operational amplifier. When used in a closed-loop configuration with negative-feedback, its current to voltage gain is based on the amount of resistive feedback.

Then the basic op-amp transimpedance amplifier has a current source connected to the op-amp’s inverting (–) input with a feedback resistor Rf between its inverting input and its output as shown:

Basic Transimpedance Amplifier Circuit

So how does the circuit work? The analysis of this transimpedance amplifier circuit is similar to that for the previous inverting op-amp amplifier. The difference here is that we have removed the input resistor R_IN and the input voltage V_IN and replaced them with a current source I_IN. Since we are not using the positive non-inverting input this is connected to a common ground or zero.

Remember that when dealing with operational amplifiers there are two very important rules. These are: “No current flows into either input terminal”, and that “V- always equals V+”. This is because the junction of the input and feedback signal is at the same voltage potential as the positive (+) non-inverting input producing a “Virtual Earth” condition.

Since the inverting input of the op-amp is a virtual earth summing point, the voltage at this point (V-) must be the same as V+, that is zero. Thus any currents flowing into this virtual earth point must sum to zero. So the input current to the op-amp is zero. That is:

I_IN + I_R = 0

Since the inverting op-amp both amplifies and inverts its input signal by 180^o. This inversion means that a positive input signal will produce a negative output and vice-versa. Therefore:

I_IN = –I_R

As input V- is zero due to the virtual earth summing point, current I_R can be defined as:

–I_R = V_out ÷ R

Then we can correctly say that:

I_IN = –I_R = V_out ÷ R

Rearranging above produces the following transimpedance amplifier formula.

Transimpedance Amplifier Formula

V_out = –I_IN × R

Note that the output voltage (V_out) is directly proportional to the input current (I_IN. Thus an ideal transimpedance amplifier is a current-controlled voltage source with an infinite transimpedance gain (-R) and is sometimes referred to as a Current Feedback Op-amp Circuit or simply a Current-to-Voltage Converter.

Remember that the minus sign indicates that the input current flows in the direction of the arrow producing a negative output voltage. Thus the gain is -R and is negative.

Choosing a Suitable Feedback Resistor

As stated above, the transimpedance amplifier is a “current-to-voltage converter”, that consists of a shunt feedback across a high-gain voltage amplifier. As such it has a transfer ratio of: A = Vout/Iin. That is, it has the dimension of V/I or Resistance, which is normally expressed in V/A, or V/mA.

So when designing a transimpedance amplifier circuit we have only one component value to consider. The feedback resistor, Rƒ itself. Then as we can see, the amplifiers transimpedance gain is simply the value of Rƒ. Note that sometime the transimpedance gain is presented as “–R” showing negative resistance because it uses an inverting amplifier.

So how do we determine the value of the feedback resistor? Considering DC conditions, if Rƒ is too large, then the input current signal can saturate the op-amp’s output at either its positive or negative supply rail limits, causing clipping of the output signal.

Likewise, if R– is too small, then the output voltage signal may also be too small to be useful and therefore unable to detect small changes or variations in input current. So we need to make the feedback resistor, Rƒ sufficiently large enough to be able to detect small changes in input current, Iin without causing Vout to saturate.

Transimpedance Amplifier Worked Example No1

Let us assume we have an operational amplifier powered from a ±10 volt supply, and we want to measure input currents up to ±100 uA. Then the maximum value for the feedback resistor will be:

R = V ÷ I = 10 ÷ (100 x 10^-6) = 100kΩ or 100V/A

That is: Rƒ = 100kΩ. Therefore if we have an input current, Iin or say, 50uA, then the output voltage will be:

V = I x R = 50 x 10^-6 x 100000 = 5 volts

Remember that in this simple example, the op-amps output will saturate if the input current exceeds 100uA.

Photodiodes Convert Light into Electrical Current

One very common application of the transimpedance amplifier is to use a photodiode as its current source for use in optoelectronic circuits.

Typical Silicon Photodiode

Photodiodes are solid-state semiconductor devices that convert light energy into electrical current through the photovoltaic effect.

The basic photodiode consists of a p-n junction formed by doping silicon in the same way as for signal diodes and bipolar transistors.

When photons of light with sufficient energy strike the semiconductor p-n junction, a photocurrent proportional to the incident light intensity is generated.

Then we can use photodiodes with our high-input transimpedance amplifier to convert the small photocurrent of light into a usable output voltage signal which scales linearly with the light intensity for use in light meters or optical encoders in positional sensing applications.

A Photodiode Transimpedance Amplifier

As we can see, the anode terminal of the photodiode is connected to the inverting input of the op-amp. That is, the photodiode is connected directly across both the inverting and non-inverting inputs of the op-amp (with non-inverting terminal grounded).

The photodiode current, I_PD has the same value as the current flowing through the feedback resistor, Rƒ. This resistive feedback forces the amplifier to convert the diodes small photocurrent without there being any other external voltage being present at its input.

The amplifiers gain measures the diodes photocurrent, I_PD and converts it into an output voltage per microampere input, (V/mA) equal to the diode current times the feedback resistance, Rƒ. Thus as before, the gain of the photodiode amplifier is determined by the resistive value of the feedback resistor Rƒ. That is: A = Rƒ.

The magnitude of the amplifiers gain can also be thought of as its “sensitivity of conversion” because it gives an amount of voltage output change for a given input current change. For instance, for a sensitivity of 1 V/mA we may need Rƒ = 1kΩ. While a sensitivity of 1 V/µA we may need: R = 1MΩ, and so on.

Then selecting the correct feedback resistance can be a compromise between sensitivity and output voltage range. So in order to use our transimpedance amplifier over a larger range of input photocurrents. We can use switches to select different resistors for Rƒ to achieve different levels of transimpedance as shown.

Adjustable Photodiode Transimpedance Amplifier

The example transimpedance circuit offers a wide range of sensitivities depending upon the position of the 4-way rotary switch ranging from 100Ω for position 1 to 100kΩ for position 4. Clearly then for a given photocurrent, switch position 4 offers one thousand times the amplification of switch position 1.

We could take this photodiode transimpedance amplifier circuit one step further by replacing the rotary switch and fixed value resistors, R1 to R4 with a 100kΩ potentiometer giving us a fully adjustable gain stage to change light sensitivity.

Transimpedance Amplifier Worked Example No2

Suppose we have a silicon PIN photodiode that passes a maximum reverse current of 5 mA when fully illuminated across a spectral range of 350 nm to 1100 nm. What is the maximum value for the feedback resistor if the amplifier is fed from a single 5V supply.

Rƒ = V_{out (max)} ÷ I_{photo (max)} = 5 ÷ 0.005 = 1000 Ω (1 kΩ)

Thus a 1kΩ resistor (or potentiometer) is the maximum value of the transimpedance gain we can use to prevent the output from saturating.

Transimpedance Amplifier Tutorial Summary

We have seen here that a Transimpedance Amplifier (TIA) is a current-to-voltage converter built around a high-impedance inverting operational amplifier. Thus a transimpedance amplifier can be used to convert a sensor’s current-controlled output, I into a usable voltage, V.

This output voltage Vout is proportional to the current Iin generated at the input with the transimpedance open-loop gain determined by: Vout/Iin expressed in volts per ampere or ohms (kΩ).

The relationship between Vout and Iin and therefore its conversion gain can be accurately controlled using a feedback resistor, Rƒ with typical values ranging between thousands of ohms (kΩ) to tens of mega-ohms (MΩ).

The transimpedance amplifier circuit finds many applications in optoelectronics since it can be used to measure the very small current flowing through a silicon photodiode and convert it into a useable output voltage. Phototransistors can also provide current amplification of the detected light signals but require biasing first.

However, despite the above circuits simplicity, the current-to-voltage conversion of the transimpedance amplifier acting as a photodiode amplifier, can restrict its ac bandwidth due to the in-built parasitic capacitance across the photodiodes p-n junction.

Because any voltage developed across the photodiode reacts with its internal junction capacitance, shunting away part of the diodes photocurrent when operated at high switching frequencies. Thereby reducing its upper bandwidth.

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📚 تحميل كتاب لف المحركات الكهربية (عملي)

إذا كنت تعمل في صيانة وإصلاح المحركات الكهربية أو ترغب في احتراف مجال لف المحركات، فهذا الكتاب يعتبر من أفضل المراجع العملية التي تساعدك على فهم أساسيات التشخيص والإصلاح خطوة بخطوة.

ستتعرف داخل الكتاب على:
اكتشاف أعطال المحركات الكهربية.
التمييز بين الأعطال الكهربائية والميكانيكية.
طرق فحص وتشخيص المحرك قبل إعادة اللف.
أساسيات إصلاح الأعطال الشائعة.
شرح عملي مبسط يناسب الطلاب والفنيين والمهندسين.

التحميل مجاني من خلال الرابط الموجود في أول تعليق / على الموقع.

لا تنس مشاركة المنشور مع زملائك ليستفيد الجميع، فقد يكون هذا المرجع سببًا في حل مشكلة واجهتك يومًا داخل ورشة الصيانة.

تحميل

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Curated by Jesif Ahmed

تحميل مذكرة اختيار مقاطع الكابلات والقواطع الكهربائية

حمل دليل عملي لاختيار القواطع والكابلات الكهربائية

هل تواجه صعوبة في تحديد القاطع المناسب أو مساحة مقطع الكابل المطلوبة لأي حمل كهربائي؟

في هذا الملف ستتعرف بشكل مبسط وعملي على:

• أنواع القواطع الكهربائية: MCB، MCCB و ACB.
• طريقة حساب تيار الحمل للأحمال الأحادية والثلاثية.
• كيفية اختيار سعة القاطع المناسبة.
• أسس اختيار مقطع الكابل طبقًا للحمل وطريقة التمديد.
• تأثير درجة الحرارة وعوامل التخفيض على قدرة الكابل.
• مفاهيم هبوط الجهد وتحمل تيار القصر.
• أمثلة تطبيقية تساعدك على فهم خطوات الاختيار بشكل عملي.

حمّل الملف الآن وابدأ في فهم أساسيات تصميم واختيار القواطع والكابلات الكهربائية بصورة أكثر احترافية.

تحميل المذكرة

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تحميل المرجع فى محولات القوى الكهربية لـ د.محمود الجيلانى

تُعد محولات القوى الكهربائية من أهم المعدات المستخدمة في أنظمة نقل وتوزيع الطاقة الكهربائية، لذلك فإن فهم مبادئ تشغيلها وتصميمها واختباراتها يعد أمرًا أساسيًا لكل مهندس كهرباء يعمل في مجالات القوى الكهربائية أو الصيانة أو التشغيل.

ومن بين أفضل المراجع العربية المتخصصة في هذا المجال يأتي كتاب “المرجع في محولات القوى الكهربية” للدكتور محمود الجيلاني، والذي يعتبر مصدرًا علميًا وعمليًا غنيًا بالمعلومات القيمة التي يحتاجها الطلاب والمهندسون على حد سواء.

لماذا يعتبر هذا الكتاب مرجعًا مهمًا؟

يتميز الكتاب بأسلوب شرح واضح ومنظم يجمع بين الجانب النظري والتطبيقي، حيث يشرح العديد من الموضوعات المهمة المتعلقة بمحولات القوى الكهربائية، ومنها:

• مبدأ عمل محولات القوى الكهربائية.
• تركيب وأجزاء المحول بالتفصيل.
• أنواع المحولات واستخدامات كل نوع.
• اختبارات المحولات الكهربائية.
• الفقد والكفاءة وتنظيم الجهد.
• أنظمة التبريد المختلفة للمحولات.
• الأعطال الشائعة وطرق تشخيصها.
• أسس التشغيل والصيانة لمحولات القوى.

لمن هذا الكتاب؟

هذا المرجع مناسب لـ:

طلاب كليات الهندسة والمعاهد الفنية.
مهندسي القوى الكهربائية.
مهندسي الصيانة والتشغيل.
العاملين في محطات التوليد وشركات توزيع الكهرباء.
الراغبين في تطوير معرفتهم العملية في مجال المحولات الكهربائية.

أهمية دراسة محولات القوى

تعتبر محولات القوى العمود الفقري لشبكات الطاقة الكهربائية، حيث تساهم في رفع وخفض مستويات الجهد بما يضمن نقل الطاقة بكفاءة عالية وتقليل الفواقد. لذلك فإن الإلمام بالمفاهيم الأساسية والمتقدمة الخاصة بالمحولات يعد مهارة ضرورية لكل مهندس كهرباء محترف.

تحميل الكتاب

تحميل الكتاب

يمكنك تحميل كتاب المرجع في محولات القوى الكهربية للدكتور محمود الجيلاني PDF من خلال الرابط المرفق بالأسفل والاستفادة من أحد أهم المراجع العربية في هذا المجال.

نتمنى لكم قراءة ممتعة واستفادة علمية وعملية حقيقية، ولا تنسوا مشاركة الكتاب مع زملائكم المهندسين والطلاب ليستفيد الجميع.

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AND-OR-Invert Circuit

Explanation of the AND-OR-Invert Function

The AND-OR-Invert (AOI) function is a common combinational logic function used in digital circuits. As its name suggests, the AOI function is a logic function that performs a combination of AND and OR operations followed by an inversion (NOT).

Complex logic gates such as the AND-OR-Invert Gate, or its complementary, the OR-AND-INVERT (OAI) logic functions can be constructed using some simple Boolean rules and several discrete logic gates which can then be used to implement more complex Boolean expressions in a single, efficient step.

We know that Combinational Logic Circuits can provide different functions which consist of several NOT, AND, or OR operations connected together using two or more input variables. Multiple-input AND-OR-Invert (AOI) and OR-AND-Invert (OAI) functions can also be realised within a single complex circuit.

How Does an AOI Gate Work?

Basically, the AND-OR-Invert logic function is a three-level logic circuit that takes multiple inputs, performs AND operations on groups of inputs, OR’s the results of those AND operations, and then inverts the final output. That is, the AOI function performs a Sum-of-Products (SOP) calculation of: AB + CD followed by an inversion as shown.

The AND-OR-Invert Circuit

Then as we can see, the AOI circuit is constructed by cascading together in series three distinct stages of logic gates. Two or more AND gates are used to produce the product terms for the input pairs (A B) and (C D).

The outputs from the two AND gates are fed into the inputs of an OR gate which sums the logical products. Then the output of the OR gate is passed through a NOT gate (inverter) to produce the final complemented output at Q.

This basic AND-OR-Invert logic circuit is known commonly as an AOI22 Function. It is known as an AOI22 function because it performs two of two input AND operations and OR’s their results together. Then the output Q is determined by the inputs A, B, C, and D.

The generalised Boolean expression given for this inverted Sum-of-Product AOI22 function is expressed as follows:

The AND-OR-Invert (AOI22) Boolean Expression

Q = (A . B) + (C . D)

Where:

• The Dot (⋅) used in the terms (A ⋅ B) and (C ⋅ D) represents the AND (conjunction) operation.
• The Plus (+) symbol represents the OR (disjunction) operation combining the products.
• The Overline indicates the NOT (inversion) operation applied to the entire sum.

AND-OR-Invert Truth Table

Given the Boolean expression, the behavior of an AOI22 function can be summarised by evaluating all the possible input combinations. Since it has dual 2-input variables: A, B, and C, D with each variable having exactly 2 possible states: False (0) or True (1). This means that for the 4-input variables we will require (2 x 2 x 2 x 2) = 2⁴ = 16 rows within our truth table as shown.

D	C	B	A	A.B	C.D	(A.B)+(C.D)	Invert
0	0	0	0	0	0	0	1
0	0	0	1	0	0	0	1
0	0	1	0	0	0	0	1
0	0	1	1	1	0	1	0
0	1	0	0	0	0	0	1
0	1	0	1	0	0	0	1
0	1	1	0	0	0	0	1
0	1	1	1	1	0	1	0
1	0	0	0	0	0	0	1
1	0	0	1	0	0	0	1
1	0	1	0	0	0	0	1
1	0	1	1	1	0	1	0
1	1	0	0	0	1	1	0
1	1	0	1	0	1	1	0
1	1	1	0	0	1	1	0
1	1	1	1	1	1	1	0

Thus for the operation of our 4-input AND-OR-Invert circuit, the output is LOW (0) if both input A AND input B are HIGH (1), OR both input C AND input D are HIGH (1).

The AND-NOR AOI22 Circuit

The primary goal of an AOI function is optimisation since it combines three basic logic operations (AND), (OR), and (NOT) into one single logic block. However, you may be thinking, isn’t a Logic OR Gate followed by an inverting NOT gate the same as a NOR gate function, and you would be right!

Then we can reduce this three-gate AOI22 circuit down to just two different gates by repacing the OR-Invert part with a single Logic NOR Gate while still allowing us to implement the inverted sum-of-products expression as shown:

The AND-NOR Circuit

So as before, the AND stage takes the two sets of inputs and perform an AND operation on them: (A.B) and (C.D). While the NOR stage takes the outputs of those two AND gates and inverts them: (A . B) + (C . D).

Commercially Available AOI IC’s

While a logical function like an AND-OR-Invert may seem a bit odd at first, AOI’s are available in several different configurations within the 14-pin dual in-line package (DIP) TTL or CMOS families. They all have the same functionality and are available with a varying numbers of inputs.

Commonly available digital logic AND-OR-Invert IC’s include:

The TTL (7400 Series) ICs

• 7451 (Dual 2-input 2-wide AND-OR-INVERT gates) containing two independent AOI gates. Y = (A.B) + (C.D)
• 7454 (4-wide 2-input, 3-input AND-NOR gates) contains two independent AOI gates. Where: 1Y = (1A.1B)+(1C.1D) 2Y = (2A.2B)+(2C.2D)
• 7464 (4-2-3-2 input) has four AND gates with a different number of inputs (one 4-input, two 2-input, and one 3-input). Y = (ABCD)+(EF)+(GHI)+(JK)

The CMOS (4000 and 74HC Series) ICs

• CD4085 (Dual 2-wide 2-input AOI gate): Similar idea to the TTL 7451 but with additional chip-select/inhibit controls. Y = Inhibit + (A.B) + (C.D)
• CD4086 (Expandable 4-wide 2-input AOI gate): Additional INHIBIT/EXP input and an ENABLE/EXP input allows linking to more chips to increase the number of AND terms and therefore the “width” of the sum.
• 74HC51 High-speed CMOS version of the 7451 dual AND-OR-Invert with two distinct gates (a 2-wide 2-input gate and a 2-wide 3-input gate). Allows for compatibility with modern 5V microcontrollers and breadboard power supplies.

Wide vs. Input

What is the difference between “wide” and “input” with regards to an AOI gate. In an AND-OR-Invert (AOI) logic gate, “wide” refers to the number of AND gates, while “input” refers to how many signals go into each of those individual AND gates. Basically, how many parallel AND gate paths feed into the OR gate.

Thus a “2-wide 3-input” AOI gate means the chip has 2 internal AND gates (2-wide) with each AND gate having 3 individual inputs. So a 4-wide 2-input means four 2-input AND gates across, and so on.

Complex or asymmetrical AOI gates, such as a “3-wide, 2-2-3-input” gate simply means that there are 3 AND gates feeding the output. The first has 2 inputs, the second has 2 inputs, and the third has 3 inputs. Something like the TTL 74LS54 has a 4-wide 2-input and 3-input AND-NOR gate combinations a shown.

TTL 74LS54 AND-NOR Gate

Schematic Diagram of the TTL 74LS54 AOI IC

The NAND-AND Equivalent Circuit

We have seen above that the AND-OR-Invert function is useful for implementing complex logic expressions efficiently by combining multiple logic operations into one single digital circuit. However, one of its main disadvantages is that it uses three separate logic gates. The AND, OR, and NOT to create one single AND-OR-Invert (AOI) function.

One way to overcome this problem is to create the AND-OR-Invert function using just one single type of universal logic gate, the NAND (NOT AND) gate. That is by combining NAND gates together, we can replicate the AOI function without needing separate AND, OR, and NOT gates thereby reducing the number of different types of logic gates required.

The NAND Gate Function

The Logic NAND Gate can be used to implement any other Boolean function or gate simply by connection two or more NAND (NOT AND) gates together. This ability to create equivalent AND, OR and NOT gates using just one logic gate, makes the NAND gate a Universal Logic Gate.

The operation of the NAND gate is the same as the AND gate except that its output is inverted. Then you can think of a Boolean NAND Function as an AND function but with an inverter (NOT) at its output and as such we can use NAND gates to build an equivalent to the AND-OR-Invert circuit.

The logic NAND gate is given a symbol whose shape is that of a standard AND gate but with a circle (inversion bubble) at its output to represent the NOT function within its logical operation. The NAND gate symbol and corresponding truth table is given as:

2-input NAND Gate and Truth Table

Symbol	Truth Table
2-input NAND Gate	B	A	Q
	0	0	1
	0	1	1
	1	0	1
	1	1	0

Implementation of Universal Logic Gates using only NAND Gates

Because NAND gates are readily available in integrated circuit form, such as the 7400 (or the 74LS00 or 74HC00) quad 2-input NAND TTL chip which has four individual NAND gates within one single IC package. We can use a single 7400 TTL chip to produce all the Boolean functions of: AND, OR and NOT as shown.

Since an inverted-input OR gate is perfectly equivalent to a standard NAND gate, we can create the AND-OR-Invert function using NAND-AND gates as follows:

AOI Function Using NAND Gates

While the above AOI equivalent multi-level NAND gate circuit will work, in this form it requires eight individual NAND gates to realise the same Boolean function. However, we can see that the transition between the output of the AND stage and the input of the OR stage uses two sets on NANDs connected as inverters (NOT Gates).

Then we can simplify the switching function because the “extra” inversions cancel each other out in the second stage reducing the circuit down to four NAND gates as shown:

NAND Equivalent of AND-OR-Invert

Then while the implementation of the AND-OR-Invert function can be realised using just two gates in the AND-NOR configuration. The use of universal NAND gates is obviously a handy feature because we can be combine other NAND gates together to form all other possible logic gates using just one multigate 2-input NAND IC package such as the TTL 74LS00, or the CMOS 4011 instead.

We can also verify that the output level of the NAND circuit responds correctly to all 16 possible input-level combinations using a truth table remembering that the Boolean expression required for the AND-OR-Invert function is: (A.B) + (C.D)

NAND-AND Gate Truth Table

D	C	B	A	A.B	C.D	Q
0	0	0	0	1	1	1
0	0	0	1	1	1	1
0	0	1	0	1	1	1
0	0	1	1	0	1	0
0	1	0	0	1	1	1
0	1	0	1	1	1	1
0	1	1	0	1	1	1
0	1	1	1	0	1	0
1	0	0	0	1	1	1
1	0	0	1	1	1	1
1	0	1	0	1	1	1
1	0	1	1	0	1	0
1	1	0	0	1	0	0
1	1	0	1	1	0	0
1	1	1	0	1	0	0
1	1	1	1	0	0	0

AND-OR-Invert Tutorial Summary

We have seen here that the AND-OR-Invert (AOI) is a logic function combining AND, OR, and NOT operations to implement sum-of-products (SOP) expressions efficiently.

It is constructed by using multiple-input AND gates which take the input variables and produces a product term (a logical AND of inputs). These product terms correspond to the “products” in the sum-of-products expression.

The outputs of all the input AND gates are fed into one single OR gate which sums (logical OR) all the product terms produced by the AND stages. The output of the OR gate is then fed into an inverter (NOT gate) which complements the OR gate’s output. That is it produces an inverted SOP expression.

We have also seen that the AND-OR-Invert function can also be implemented using AND-NOR gates as well as NAND-AND gates because NAND (and NOR) gates can replicate any basic logic operation (AND, OR, NOT).

AOI logic gates such as the TTL 7454 or 7464 are useful because they combine multiple logic functions into a single gate structure with the AOI logic built at the transistor level. However, when designing a new combinational circuit and cannot source these AOI logic IC chips. Then as we have seen, AOI gate equivalents can be constructed using basic TTL or CMOS NAND gates as shown above.

The post AND-OR-Invert Circuit appeared first on Basic Electronics Tutorials.

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Credit- Basic Electronics Tutorials. Distributed by Department of EEE, ADBU.
Curated by Jesif Ahmed.

تحميل المرجع في التركيبات الكهربية – أ.د. محمود الجيلاني

تحميل المرجع في التركيبات الكهربية – أ.د. محمود الجيلاني

إذا كنت طالب هندسة كهربائية، أو مهندس تصميم وتنفيذ، أو تعمل في مجال التركيبات الكهربائية، فإن كتاب “المرجع في التركيبات الكهربية” للدكتور محمود الجيلاني يُعد من أهم المراجع العربية التي لا غنى عنها في المكتبة الهندسية.

يشرح الكتاب أساسيات وأنظمة التركيبات الكهربائية بأسلوب علمي مبسط، ويغطي العديد من الموضوعات المهمة مثل:

تصميم وتنفيذ التركيبات الكهربائية للمباني
حساب الأحمال الكهربائية
اختيار الكابلات والقواطع المناسبة
أنظمة التأريض والحماية
لوحات التوزيع الكهربائية
اشتراطات ومعايير السلامة الكهربائية

يُعتبر هذا المرجع من الكتب القيمة التي يعتمد عليها الكثير من المهندسين والطلاب لفهم الجوانب العملية والنظرية للتركيبات الكهربائية.

يمكنك الآن تحميل الكتاب مجانًا من خلال الرابط

تحميل الكتاب

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Distributed by Department of EEE, ADBU.
Curated by Jesif Ahmed

تحميل كتاب نظم الحماية الكهربية – أ.د. محمود الجيلاني

إذا كنت مهندس كهرباء أو طالبًا في هندسة القوى الكهربائية وتبحث عن مرجع عربي متميز في مجال الحماية الكهربية، فإن كتاب “نظم الحماية الكهربية” للدكتور محمود الجيلاني يُعد من أهم المراجع التي تشرح أساسيات وأنظمة الوقاية في شبكات القوى الكهربائية بأسلوب عملي ومبسط.

يتناول الكتاب:
أساسيات نظم الحماية الكهربية.
أنواع الأعطال في شبكات القوى الكهربائية.
أجهزة الحماية (Protective Relays) ووظائفها.
قواطع الدائرة الكهربائية (Circuit Breakers).
مناطق الحماية والتنسيق بين أجهزة الوقاية.
حماية المحولات والمولدات وخطوط النقل وقضبان التوزيع.

ويتميز الكتاب بعرض المفاهيم الهندسية بلغة عربية سهلة مدعومة بأمثلة عملية وصور توضيحية تساعد المهندسين والطلاب على فهم أنظمة الحماية الحديثة وتطبيقاتها في الواقع العملي.

كتاب مهم لكل مهندس يعمل في مجالات القوى الكهربائية، التشغيل، الصيانة، الاختبارات، والحماية.

يمكنكم تحميل الكتاب والاستفادة من محتواه القيم لتطوير معارفكم في مجال حماية نظم القوى الكهربائية.

تحميل الكتاب

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Distributed by Department of EEE, ADBU.
Curated by Jesif Ahmed

كل ما تحتاج معرفته عن أنظمة فرملة المواتير والفرملة الكهربائية

هل تعلم أن توقف المحرك خلال أجزاء من الثانية قد يكون العامل الأساسي في حماية المعدات، وزيادة الأمان التشغيلي، وتقليل الأعطال المكلفة داخل المصانع؟

في العديد من التطبيقات الصناعية مثل الرافعات، السيور الناقلة، المصاعد، أنظمة المناولة، وخطوط الإنتاج، لا يكفي أن يعمل المحرك بكفاءة فقط، بل يجب أن يمتلك نظام فرملة قادرًا على إيقاف الحمل بدقة وأمان عند فصل التغذية أو في حالات الطوارئ.

هنا يأتي دور المحركات المزودة بفرامل كهرومغناطيسية، والتي تُعد من أهم الحلول الهندسية المستخدمة للتحكم في الحركة ومنع الانزلاق أو الحركة غير المرغوب فيها للأحمال.

في هذه المذكرة ستتعرف على:

مبدأ عمل الفرامل الكهرومغناطيسية (Electromagnetic Brakes)

الفرق بين أنظمة الفرملة AC و DC

كيفية حساب واختيار عزم الفرملة المناسب (Braking Torque)

أزمنة الفصل والتعشيق وتأثيرها على الأداء

متطلبات التشغيل مع أنظمة الـ Variable Frequency Drives (VFD)

التطبيقات الصناعية المختلفة لمحركات الفرامل

الاعتبارات الفنية الخاصة بالاختيار والتشغيل والصيانة

دوائر التوصيل والمفاهيم الأساسية اللازمة للمهندسين والفنيين

إذا كنت مهندس كهرباء أو تحكم أو صيانة صناعية، فهذه المذكرة ستساعدك على فهم أحد أهم مكونات أنظمة الحركة الصناعية، وتمنحك أساسًا قويًا لاختيار وتشغيل محركات الفرامل بالشكل الصحيح.

تحميل الكتاب

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Distributed by Department of EEE, ADBU.
Curated by Jesif Ahmed