Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [circuits]

217 questions
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6 answers

Why does my circuit work on a breadboard, but not on a perfboard? I am new to soldering

I'm a total beginner when it comes to soldering, and recently I've been trying (and failing) to solder together a simple circuit I put together for a Raspberry Pi sensor. Although it works fine on the breadboard, when I solder it onto one of my…
Sebastian Villate
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What went wrong with my DIY project?

I have been teaching my son the basics of electronics by taking apart his old toys. We got to the level where we can fix things and put them back together. Last weekend we spent several hours putting the circuitboard of RC car #1 into RC car #2,…
Wapiti
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What are some practical examples of a constant current source?

Please don't state the obvious that nothing is a perfect constant current source. And please do not give examples of how to create them from components. I looked at this SE Q/A which stated the obvious - that you can not have a perfect current…
jennifer
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How do I build an electromagnet?

I want to make an electromagnet that can lift a paper clip off of the ground from a short distance (probably 7 to 8 inches). I naively thought of making an electromagnet as a simple task (because of the short videos which make it seem so simple),…
Will
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3 answers

In the context of a differentiator circuit, what is a “current-sensing resistor”?

I’m reading through The Art of Electronics and am puzzled by the use of the term “current-sensing resistor” as it pertains to differentiator circuits. In the above figure, the author explains that a perfect differentiator could be made from a…
Bryan Coxwell
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2 answers

Different voltage sources in parallel

I realize connecting two different voltage sources in parallel is a contradiction (in an ideal circuit). But if I were to connect this in practice and measure the voltage across points A and B, what value of voltage would it show? And how much…
penguin99
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What is the circuit symbol for a triple gang potentiometer?

What is the circuit symbol for a triple gang potentiometer? I've found one possibility for dual gang potentiometers: (Image source: Components101 - Different Types Of Potentiometers And How To Use Them In Your Designs) But this symbol can't be…
iwantmyphd
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Paradox: potentiometer short circuits between tracks which never touch

I can solder and use basic features of multimeter so excuse my ignorance. This is driving me crazy, this a potentiometer from speakers which lost left channel sound. I disconnected the volume control (potentiometer) connected directly and both…
BeBu
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6 answers

Charging of capacitor in RC circuit

When a capacitor is charged in a first order RC circuit, it charges exponentially. I understand this behavior via equations. But can anyone explain the physical reason?
sumita sahu
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How does an ideal op amp amplify a voltage input when the voltage difference is 0?

I am a first year Electrical Engineering student. Next week I have my exams on Op Amps and their applications and such. While looking at the op amps, there was always this one this that was confusing to me: in a non inverting amplifier, the inputs…
J. Teurlings
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If there exists a cascade of op amps, does the previous op amp's slew rate affect the later op amp's slew rates?

All op amps used are the same Texas Instrument LM348n. The datasheet says the op amp has a nominal slew rate of 0.5 V/µs, but gives no tolerance. I have a square signal with an amplitude of 500 mV peak to peak being sent into a two op amps system.…
Jonathan Riley
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"Circuits" - A convenient teaching tool?

At school, we are taught that electricity requires a complete circuit for current to flow. We are later taught that current flows from areas of high voltage to lower voltage. So, current can always flow from a high-voltage line into ground since the…
ScottishTapWater
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Averaging thermistor readings

I have 9 thermistors arranged in a grid, and I want to average the readings from these thermistors without code (that is, average them in a circuit rather than reading all the values into a microcontroller and averaging within code) - for speed. The…
William Faust
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5 answers

Boolean Logic - Realization with using only 4 NAND gates

I am currently preparing the next semester of my program at university and I am stuck at a question of the "Digital Circuits" class. Here is the task: [...] pump P1 runs when the fill-level of the tank falls below 90% (U=0), however only when the…
jesm86
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How can I control 8 LEDs using only 5 pins of a microcontroller?

How can I control 8 LEDs using only 5 pins of a microcontroller without using any shift registers or I/O expanders? By "controlling" I mean turning an LED or a set of LEDs on or off, not just turning one only at a time like Charlieplexing. Edited :…
Mohamed Atef
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