# Questions tagged [basic]

Fundamentals of electricity, electronics, components, or theory

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### When you connect two batteries in series, why doesn't the middle short?

When you connect two batteries in series, why doesn't the middle short? The connection between the positive terminal on one battery and the negative terminal on the other battery has no load, so ...
94 views

### Output composite video (PAL) signal from FPGA DAC, totally lost in the analog domain

I'd like to start generating (and perhaps also capturing) composite video (PAL) signals from a digital source, eg. FPGA. However, while my digital logic/programming skills are covered, I'm lacking a ...
413 views

### Find the Thevenin's equivalent of a circuit between nodes A and B

My class had come to discuss the Thevenin's theorem and we stumbled upon this particular problem which quite confuses me in a way that what I found is different than what my lecturer taught us. So, ...
33 views

### Simulation not working well in Proteus 8.12

I'm not understanding Proteus or something I'm doing wrong, and it's really basic, I put a 9v Battery, a Red Led, simple circuit and a 10k resistance, so the led shouldn't turn on right? Well, is ...
118 views

### Does a floating load on a transformer have no voltage difference with ground?

I think I know the answer, but I'm unsure. I'm studying for my FE, and in the practice exam is the following question: An ideal transformer connects a 120-V, 60-Hz voltage source to a load. One ...
1k views

### Calculating energy absorbed by an element

I need your help to understand the solution to the given question where energy absorbed needs to be calculated with the given graphs of the current and voltage through the element. Please help explain ...
58 views

### Basic RL curcuit problem

So I had an exam in basic electronics, which I passed but lost a lot of points on one seemingly easy task. "Through the coil is passing a current equal to $i_L=200\sin(10^5 t + 210°)$. If R=5 ...
59 views

### Am I overthinking this simple power supply connection?

I want to connect a 12V fan and a motorcontroller to this generic ac to 12v dc power supply. The motorcontroller is pulling around 25 amps, and the fan about 1. I'm just wondering, should i add a ...
127 views

### How to find current through inductor when connected in series with an ideal diode?

Please help me with this simple circuit, which is creating lots of confusion due to different results from theoretical calculation and SPICE simulation. Ques: In this circuit switch is closed for time ...
82 views

### Resistors in series to increase maximum Voltage

Do the values of resistors matter when I want to use them in series to increase the maximum voltage they can handle? So can I just use a 1 megohm resistor for example that's rated for 200 V and then ...
85 views

### Controlling a motorized ball valve and appliance with a float switch(es)

I am trying to create some redundancies for a small commercial ice maker to prevent there from ever being a flood in my garage. The ice melts from the ice bin (which holds around 80lbs of ice) ...
172 views

### Kirchhoff Voltage Law in a two port network

In a tutorial about h parameters of a two port network, I find the below snippet in the image unable to grasp. According to KVL, the total voltage in a loop is the algebraic sum of the individual ...
8k views

### Double-Subscript Notation for Voltages

I have read from some book that: "The voltage quantity symbol V sometimes has subscripts to designate the two points to which the voltage corresponds. If the letter a designates one point and b the ...
150 views

### Undervoltage lockout

I would like to do a simple undervolatge lockout. I thought a BJT as a switch like this: In normal conditions I would have 30V (and -30 and the othre rail) and 25 mA to 50 mA. These power rails will ...
3k views

### Calculating for Load Resistance given a T network in between the source and the load

Problem: Calculate the value of load resistance (Rl) for which maximum transfer occurs. Attempt: What I know is that for the maximum transfer to occur, the load resistance must be equal to the source ...
235 views

### Basic question about conduction current

Sorry for my english and long post again. After reading this article, I realized that my understanding seemed to be wrong. I thought that to create conduction current in some wire first we need a "...
49 views

### Power Supply stopped working after soldering

I am new to electronic circuits. I built a basic led circuit on a breadboard to test everything out.It worked as in pictures,but the connections were not stable because the holes were very large.I ...
135 views

### How to get negative voltage?

There's a bunch of posts about this, but they're all for very specific scenarios. I'm a newbit, and some components, like op amps, require both a positive, and negative voltage. But how do you get ...
90 views

### Why is the resistance of parallel circuits lower than either of the individual parts

I am watching this tutorial, and topic of parallel circuits came up. In the below image, the combined resistance is 60Ω, which is less than either of its parts (150Ω and 100Ω). I understand how the ...
158 views

### Voltage of capacitors after long time (RC Circuit)

I'm currently taking a course in electromagnetism, and I got stuck with this problem: The Problem: All of the resistors and capacitors have the same values, R and C respectively. The circuit is ...
296 views

### Working of bipolar junction transistor with electron flow

I faced a lot of problems in understanding BJT. I am going to share what works for me. Suppose we take an NPN as the transistor in our case. The emitter base region is forward biased, so electrons ...
75 views

### I'm trying to make a clock pulse generator but when I run the simulation nothing happens

I am new to using circuit/breadboard simulation apps. When I run the simulation nothings happens. Here is the original schematic. Edit: I'm using 74HC00. Also I learned how to use Virtual Breadboard ...
89 views

### Why can't KVL be applied here?

I was asked to find the Is current I applied KVL in that loop but my ans is wrong. what concept is wrong on my approach?Why kvl cant be applied on that loop please explain
2k views

### NTC 5d thermistor and how to use it

I bought a random thermistor for a circuit I'm planning to build and it turned out to be a NTC 5D-15. I'm trying to build this test circuit: After doing a bit of research, that thermistor resistor ...
4k views

### If Conventional Current is wrong, how can I trace the flow of current in a schematic?

If Conventional Current is backwards, how do I look at something like this schematic and trace the flow of current? I'd like to follow the design linearly from positive to negative. When the battery ...
4k views

I'm a computer scientist with zero exposure to things directly related to hardware (barring what I learned from my undergrad computer org class.) I've been very attracted to the field of embedded ...
649 views

### How to understand the “basics” of electricity? [closed]

I want to be a self-taught computer engineer ... massive goal, but it's what I want eventually. I check out textbooks and online resources, but I feel like I need a prerequisite somewhat -- I still ...
269 views

### Electronics by Example [closed]

I am interested in learning more about electronics. I know some basics about resistors, capacitors, transistors, and diodes. I would like to learn more about things such as operational amplifiers, ...
302 views

### How and where can I start learning about electronics? [closed]

I really want to know how electronic devices work. So as someone who actually knows nothing about basics, how can I start learning it? What sources should I use? Is it really needed to be studying at ...
242 views

### Where can I learn? [closed]

So I'm looking at Open Courseware but I'm not sure what course to look at, I'm looking for a course that will teach me how to build an embedded Linux device such as a Rpi, Beagle bone etc. (a.k.a has ...
295 views

### Beginning with programming microcontrollers [closed]

I am a software developer (coming from Java and Javascript/web-app programming) and I'm very interested in programming microcontrollers like Arduino or Espruino. The problem is I have little to no ...
877 views

### Roadmap for learning Electrical Engineering [closed]

I am just starting to learn electrical engineering, but I am confused about what I should do. Should I be reading about it, taking online classes, or just make projects? If possible can you provide me ...
161 views

### Oscilloscope training resources

I would like to learn to use an oscilloscope properly. I used them a few times at school, but that was a long time ago and I've forgotten most of what I learned about their use. I'm now working with ...
3k views

### Where can I find beginners electronics project schematics online, for free? [closed]

I have bought the following books in order to start learning basic electronics: Electronics All-In-One Desk Reference For Dummies Robot Building for Beginners (Technology in Action) My desire though,...
6k views

### What's a good way to start learning how electronics and circuits work? [closed]

I literally already tried getting a degree in Electrical Engineering, and I hated it, and I switched to Computer Science. But here's the thing-- I find circuits and electronics and electrical devices ...
141 views

### Starting point for a 10 year old [closed]

I am a EE and would like to get my 10 y.o. nephew familiar with the fun side of electrical projects. I'd like to start with basic principles and projects to re-enforce the basics. The goal is to ...
229 views

### Why the power supplies limit the amperage?

I'm just learning electronics, and I can't understand something: If the amperes don't matter in terms of burning the circuit, only voltage, why do phone charges for example have a low current ...
569 views

Unfortunately, all I've learnt so far are concepts. I do not know where to start, but I have made a commitment to practically build some electronics. I want to ask where can I learn and acquires the ...
187 views

### Why does such a lamp and two battery circuit not work?

Assume I have a lamp and I connect one side to the + pole of one battery, and then the other side to the - pole of another battery (say two batteries of 1.5V). The remaining - and + poles are not ...
12k views

### How does this SIM card reader circuit work?

The circuit for a SIM card reader is shown here. The circuit uses a CMOS hex inverter and other simple components; yet, not only does it work but it can also communicate with a PC via serial port! I ...
348 views

### EE for Software engineers [closed]

Recently I've started playing a lot with 3D printers, Adrunio, Pandaboards and Kinect's SDK. I'm starting to have more and more passion for this sort of devices and I think it's about to turn into a ...
14k views

### Electronics course - From basics to designing circuits [duplicate]

Possible Duplicate: From zero to “almost pro”: Newbie trying to learn. Good, quick resources? What good resources are there for a high school student to start learning electronics? I am trying to ...
5k views

### Path for a child to learn electrical engineering

What are some paths for a child (7-year-old) to learn electrical engineering (in a safe way)? I do not want to saturate (or frighten away) the child with lots of concepts, I want that my son learn ...
3k views

### From zero to “almost pro”: Newbie trying to learn. Good, quick resources?

I am a total zero in electronics. I just know what is a resistor and what is a capacitor. I also know what is a 555 just because I've been told what it does, 15 years ago. Apart from this and a bunch ...
32k views

### How does an astable multivibrator LED blinking circuit work?

I am a beginner in electronics. I come to know about the oscillator using RC circuits (capacitor charge and discharge and time constant tells the behavior of circuit). Then I saw the following ...
83 views

### ADC is giving fault codes when I touch thermistor attached to it

I am working on writing a control program for my pellet smoker. I am having an issue with the meat thermometer that came with the smoker. I have a MAXIM 31865 ADC that is connected to a Raspberry Pi. ...
114 views

### Will Kirchoff's voltage law work in a vacuum

Kirchoff's voltage rule tells us that the sum of voltages around a closed loop in a circuit will equal zero. If a battery sits on a table, using KVL and treating air as matter with high resistance ...
116 views

### How to modify the supply voltage requirement in a circuit?

I am a beginner in Electronics; I am learning the basics and am trying to take up circuitry as a hobby! My query is regarding power supply requirement for any circuit. Take, for example, a circuit to ...