# electrical engineering

1. ### Thevenin's theorem BJT derivation

Here, I want to use Thevenin with those 2 resistors in the base. How can I combine those two resistors with thevenin or do you have any other better idea to combine them? (circled with red in the picture) (PS: I don't ask the solution of the question. I'm only asking individually the...
2. ### Input and Output Impedance of the Common Emitter Amplifier

Hi, I just have solved one of the bjt common emitter question below. However, I'm curious that how can I additionally find those things below: 1) Input and Output Impedance 2) AC Gain Here is the example and my hand draw solution. However, the question only asked to find Vout/Vin... Also, my...
3. ### draw the dc output voltage in a graetz circuit

Draw the dc output voltage and voltage across T3 in a Graetz Circuit when firing angle is 45 degree and u=30 degree.
4. ### Inverse Phasor Transform Calculation

While I was converting this with the inverse phasor transform, I wanna ask a question P{ -4 cos(200t – 45°)} Should I say -4∠-45 or 4∠-45 ? I mean, do I have to preserve the negativity of the magnitude which is "4"? As far as I have known that the magnitude is not a vectorial thing and then...
5. ### Sinusoidal Graph Drawing Problem

The was an equation given like that: v(t) = 5cos(1256t-pi/4) Then I wanted to draw this graph below: Do I need to scroll the chart left or right? (In the cosine graph, I shifted it to the left side) Also I want to ask that, I have been always encountered with sine function graph drawings...
6. ### Determining the period of RMS sinusoidal waveform

Here is the i (graph a) and i^2 graph (graph b) for the RMS calculation: My question is while calculating RMS value, should I decide to determine the period by looking a) or b) graph? Because, while I'm looking for the a. graph (shown above), I guessed the period is 2pi However, if I would...
7. ### Conductor volume calculations

Hello, there is a subject I need to research, but unfortunately I could not find a detailed source. I would be very grateful if you could guide me to investigate. So I can go on and read it myself. Thank you very much in advance, best regards ... The calculations of Conductor volume ( Conductor...
8. ### Why is cosine so important in Electrical Engineering?

Actually I have been thinking this question since 1 week inside my head. As far as I know that those functions are coming from "Euler's Equation" but I still concerned that what such kind of real life things are making cos and sin functions are so important for us? I just know that those...
9. ### Is there a test network to analyze the hydrothermal dispatch of electrical energy?

Hello, I am developing my degree work on the coordination of hydraulic and thermal units in an energy network and I was wondering if there is any test network with which I can evaluate or compare the results obtained with my work. Thank you very much in advance
10. ### SMD Capacitor selection

Hello everyone, How can we calculate the voltage rating of an SMD ceramic capacitor. Is it dependent on the package size?.
11. ### Design Reference Sources (NFPA, NEC Codes & Standards)

Hello All, I am a young professional electrical engineer who has just started working in Automation field. We build customized panels including PLCs, HMIs, Pushbuttons, Lights, Relays etc., I have been searching for a reference codes and standards that can be helpful for designing and wiring...
12. ### Need your advices on how can I estimate the voltage at the terminals the thyristor switch

I am working on a static transfer switch which aim is to allow supplying a load with 2 different sources in order to have a redundancy when feeding the load. The head to tail assembly allow the current to flow in 2 directions (for each alternative of the input current) The working condition is...
13. ### Software to develop electrical wiring diagrams (Training)

Hello Everyone, I am a young professional who has just started working in automation Industry as an electrical engineer and looking for a light scale software to develop electrical wiring diagrams for automation projects. My circuits mainly consists of PLC, HMI, IOs, E-Stop, Switches, Sensors...
14. ### Circuit Analysis

For Question 2.1, is the power 500W or 100W ? Do we need to apply the passive sign convention rule for power in whatever cases? Also, i’ve Learnt that we can check answers by balancing power in a circuit. But the power in this kind of circuits don’t balance out, but it is still valid. So when...
15. ### Touching live wires on high voltage line.

Hey everyone :) I'm working as an automation engineer and I've always asked myself why people say, that for example birds, can sit on power-lines, because they aren't touching neutral/different potential and no current is flowing. I can't really get this explanation into my head, because...
16. ### Do we select a large or small BJT to amplify high frequency response?

Part of me thinks we need a smaller BJT, to reduce base emitter junction area. but I am confused

18. ### LTspice Error: Undefined symbol in: "<<voltage>>" on mac.

Hey y'all! Hope you're having a great day! I've spent an unnecessary amount of time trying to resolve this issue. I'm pretty new to LTspice and I wanna simply change the x-axis to show voltage instead of time, but it just doesn't seem to work (I'm running the program on mac). As you can see in...
19. ### Transfer 24 VDC to 1000 ft...

Hello, I have to transfer 24 VDC to 21 devices which is 1000 ft apart. Is it possible to transfer 24 VDC to such a long distance? This 24 VDC is coming from SMPS. Does the current/power rating matter in this case? And how can I calculate total voltage drop at the end (If there is any)?. All...
20. ### Communication Protocols :- DeviceNET, Profibus-DP and Profinet

Hello, I am designing an automation solution where I have 40 Electrical valve acuators to connect my PLC. I am considering two types of actuators with different communication technology. Solution 1: Modbus TCP/IP Solution 2: DeviceNET, Profibus DP and Profinet (Not quite familiar with this)...