Greatest Hits

40
votes
2answers
530k views

What do solid/striped lines on a wire indicate?

What do solid or dashed lines on a wire indicate? Is there a difference between the solid and dashed indicators?
563
173
votes
4answers
228k views

USART, UART, RS232, USB, SPI, I2C, TTL, etc. what are all of these and how do they relate to each other?

As a novice electronics hobbyist, I have heard these terms and more being thrown around everywhere. At its root, I understand that they are all based on communication between devices, computers, ...
72
votes
9answers
254k views

How does a capacitor block DC?

I am confused with this! How does a capacitor block DC? I have seen many circuits using capacitors powered by a DC supply. So, if capacitor blocks DC, why should it be used in such circuits? Also, ...
279
votes
5answers
368k views

Choosing power supply, how to get the voltage and current ratings?

Power supplies are available in a wide range of voltage and current ratings. If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to ...
62
votes
4answers
319k views

Does mAh measure how long a battery would last?

I know mAh tells how much milliamperes a battery can deliver in an hour. But does that also tell how many hours the battery would last? Sorry but I don't really get it. If we're talking about a water ...
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87
votes
10answers
290k views

Why does a Tesla car use an AC motor instead of a DC one?

I was just watching a mega factory video and wondered why they use an AC motor which requires a power inverter instead of DC which may be powered directly from their DC battery? Introducing an ...
194
votes
13answers
248k views

What's the difference between a microcontroller and a microprocessor?

What's the difference between a microcontroller and a microprocessor?
25
votes
6answers
307k views

How to Calculate the time of Charging and Discharging of battery?

How do I calculate the approximated time for the Charging and Discharging of the battery? Is there any equation available for the purpose? If yes, then please provide me.
25
votes
5answers
374k views

how to reduce DC voltage using resistors?

How would one go about using a 12 V DC power source to power something which needs 4.5 V DC using resistors? Is there a way to determine how much adding a resistor would drop the voltage?
70
votes
11answers
333k views

How can I tell the size of a barrel power connector?

Spring cleaning, and I'm trying to get power supplies for all my devices with missing power supplies. They're all the typical barrel power connector, and I'm having a dickens of a time trying to ...
34
votes
8answers
263k views

Saving Arduino sensor data to a text file

How can I save data retrieved from a sensor to a text file on the computer?
633
53
votes
9answers
249k views

Difference between latch and flip-flop?

What is the difference between a latch and a flip-flop? What I am thinking is that a latch is equivalent to a flip-flop since it is used to store bits and is also equivalent to a register which is ...
293
votes
8answers
280k views

What is the difference between \$V_{CC}\$, \$V_{DD}\$, \$V_{EE}\$, \$V_{SS}\$

I've seen lots of schematics use \$V_{CC}\$ and \$V_{DD}\$ interchangeably. I know \$V_{CC}\$ and \$V_{DD}\$ are for positive voltage, and \$V_{SS}\$ and \$V_{EE}\$ are for ground, but what is the ...
53
votes
6answers
151k views

Relation and difference between Fourier, Laplace and Z transforms

I have become a bit confused about these topics. They've all started looking the same to me. They seem to have the same properties such as linearity, shifting and scaling associated with them. I can't ...
10
votes
8answers
174k views

How to convert an expression from SOP to POS and back in Boolean Algebra?

How to convert a Sum of Products (SOP) expression to Product of Sums (POS) form and vice versa in Boolean Algebra? e.g.: F = xy' + yz'
6
votes
6answers
190k views

Open and Short Circuit questions

I am confused on the terms Open, Short, and Closed when talking about circuits. As far as I know: a) Open circuit means the wires are cut off so there will be no current flow, but there is voltage. b)...
66
votes
9answers
372k views

How much voltage/current is “dangerous”?

Related: Safe current/voltage limit for human contact? From what I've heard: 110 V (or 220 V; household voltage pretty much) is dangerous (i.e. can kill you) I think there's consensus on this, ...
30
votes
4answers
276k views

Headphone wire color coding

How do I tell which wire is which if I have a copper wire, red and green coded wire? Is the unshielded copper wire ground?
90
votes
4answers
352k views

What are the different types of solder used for?

How do I know when to use lead, flux-core, lead-free, or any other kind of solder out there? Do you have any tips on solder gauge for specific applications?
413
34
votes
8answers
255k views

How are current and voltage related to torque and speed of a brushless motor?

I know that electric vehicles have different performances depending on battery and motor, but it's not clear how electrical and mechanical units are related. Can anybody please help? Will a 100V ...
15
votes
2answers
245k views

How do I calculate the cutoff frequency of a low pass rc circuit?

I want to calculate the cutoff frequency for a specific filter, but I can't find any formula for that. I know the formula for the cutoff frequency of a low pass filter: $$f_c=\frac{1}{2\pi RC}$$ ...
7
votes
3answers
118k views

definition of power signals and energy signals

Why is it so that for a signal to be an energy signal it must have power zero and for a power signal the energy value should be infinity ?
497
92
votes
5answers
255k views

Why are there 3 pins on some batteries?

Lots of new batteries (for mobile devices, MP3 players, etc) have connectors with 3 pins. I would like to know what is the purpose of this and how should I use these three pins? They are usually ...
24
votes
6answers
232k views

Reducing voltage with resistors

I have been looking around for an easy way to convert 12V to 5V. I have seen some people saying that a simple resistor is all that is needed. $$ Volts = Ohms \cdot Amps $$ $$ Amps = \frac{Volts}{...
94
votes
10answers
235k views

What is negative voltage?

Just a general electronics question: What is negative voltage, like -5 Volt? From my basic knowledge, power is generated by electrons wandering from the minus to the plus side of the power source (...
414
12
votes
12answers
128k views

How is it possible to have high voltage and low current? It seems to contradict the relationship between current and voltage in E=IR

I have read different forums and watched a few youtubes (in addition to my textbook readings) and the explanations seem to fall short. The issue seems to be how we are first taught about a direct ...
70
votes
7answers
237k views

What is “forward” and “reverse” voltage when working with diodes?

What is the difference between "forward" and "reverse" voltages when working with diodes and LEDs? I realize this question is answered elsewhere on the interwebs such as wikipedia, but I am looking ...
368
72
votes
6answers
190k views

What is the relation between FFT length and frequency resolution?

If I have sampled a signal using proper sampling methods (Nyquist, filtering, etc) how do I relate the length of my FFT to the resulting frequency resolution I can obtain? Like if I have a 2,000 Hz ...
398
53
votes
8answers
147k views

Why is high input impedance good?

Naive perhaps, but Why is high input impedance a good thing? Is high input impedance always a good thing?
418
36
votes
9answers
110k views

What is the reverse recovery time in a diode?

What is the reverse recovery time in a diode?
452
208
votes
7answers
192k views

Why was Mini USB deprecated in favor of Micro USB?

Mini USB connectors were standardized as part of USB 2.0 in 2000. In 2007, the USB Implemeters Forum standardized Micro USB connectors, deprecating Mini USB connectors four months later. Why? What ...
14
votes
3answers
206k views

Can you clarify what an 1NO1NC switch is?

I've come across multiple mentions of switches described as 1NO1NC. They often described as having 2 options: ON/(OFF) and (ON)/OFF and from what I gather they have 3 terminals for wires: a NO ...
348
107
votes
7answers
364k views

What’s the proper soldering iron temperature for standard .031" 60/40 solder?

I recently purchased a Weller WES51 soldering iron as my first temperature controlled iron and I'm looking for recommendations on the best default temperature to use when soldering. I'm using mainly ....
7
votes
2answers
16k views

What is this flat metallic component?

What is the metallic component, labeled Y1, just at the right of the integrated circuit and at the left of the small C4 and C5 capacitors? When I search for “N24.000” on Google, I find only other ...
8
votes
5answers
214k views

What is the minimum required voltage for charging a 3.7 V Li-ion battery?

I have a cell phone battery that has the following written on one side: 3.7 V 1000mAh Limited charge voltage: 4.2 volts I understand that the first line means, that the battery will always give 3....
37
votes
8answers
216k views

How can I tell charge-only USB cables from USB data cables?

Like most computer hobbyists and programmers, I've amassed boxes of USB cables to connect USB, Micro-USB, and Mini-USB to chargers, computers, and gadgets. These cables are a mix of phone charger ...
190
21
votes
1answer
139k views

Differences between OLED, LED, LCD, and TFT Screens

I have heard about these different types of screens on DIY websites and in consumer electronics. What are the differences in these types of screens and what are their advantages and disadvantages?
325
12
votes
11answers
179k views

What are the behaviors of capacitors and inductors at time t=0?

Do capacitors act as an open circuits or closed circuits at time t=0? Why? What about inductors? I tried it out, and what I got was this: Initially when I opened the switch, the capacitor acted like ...
316
votes
6answers
71k views

Why is there so much fear surrounding LiPo batteries?

I've been trying to design a charging system for a small robot powered by a 2S 20C lithium polymer (LiPo) battery. Were I to trust everything I read online, I would believe that the LiPo will kill me ...
16
votes
7answers
140k views

Why does the thickness of a wire affect resistance?

A teacher explained why by using a highway analogy. The more lanes you have, the faster the cars go through, where the number of lanes obviously represent the wire thickness and the cars represent ...
6
votes
5answers
16k views

What purpose are the transistors serving in this CRT oscilloscope circuit?

So this is part of a CRT oscilloscope diagram, and I don't understand the function of the transistors on the bottom right, Q18 and Q19. Their outputs (41 and 42, crossing through the dotted line) go ...
30
votes
6answers
262k views

VHDL: Converting from an INTEGER type to a STD_LOGIC_VECTOR

I built a mod-16 counter, and the output result is a INTEGER (all the examples I saw used INTEGER). I built a hex-to-7-segment-display decoder, and its input is a STD_LOGIC_VECTOR (wrote it that way ...
237
9
votes
2answers
123k views

What is the purpose of carbon brushes in an electric motor

I just took apart our washing machine to replace the carbon brushes. Was wondering why the machine stopped working when the brushes were worn down? Also if the engine makes a wuring noise after you ...
333
29
votes
6answers
209k views

Slow Blow vs Fast Acting Fuse

Is there any way to tell the difference between a slow blow and a fast acting Fuse? I had one blow in my amp and I know its 125v 5a, but i'm not sure if it is a slow blow or fast acting fuse. Is ...
248
-3
votes
6answers
111k views

how to calculate total resistance in circuit with parallel and series resistors connected

A battery of EMF 8.0 V and internal resistance r = 1.0 – is connected to an external circuit as shown: I need to find out the total resistence and my problem is that I dont know which resistors ...
2
votes
3answers
82k views

What is reverse saturation current?

The official page of Wikipedia mentions that reverse saturation current is a part of minority current caused by the drift of charges. I am really confused about this. In class, we have been taught the ...
12
votes
3answers
87k views

What is Q-point of transistor?

What is the Q-point of a transistor? Why it is needed? How can we set this Q-point of transistor? Please explain it as I am having difficulty understanding this concept.
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16
votes
7answers
134k views

Torque kgcm (what is kgcm)?

I know what torque is but I find difficult to understand what Torque: 3kgcm means ? I am not sure, how much weight that motor can carry, and I want to know how I can calculate that. Please give me ...
35
votes
4answers
129k views

What does edge triggered and level triggered mean?

I am studying 8085 microprocessor architecture and the word edge triggered and level triggered confusing me really very much. Can anyone explain me it in layman's words ? While studying the ...
4
votes
5answers
17k views

Difference between the following two very basic circuits

What is the difference between the below two circuits? I know the bottom circuit has 'ground', but what does that mean exactly? Why would someone want to construct the second circuit over the first? ...

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