# Greatest Hits

500k 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?
224k 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, ...
249k 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, ...
314k 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 ...
361k 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 ...
285k 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 ...
247k views

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

What's the difference between a microcontroller and a microprocessor?
358k 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?
292k 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.
318k 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 ...
255k 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?
243k 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 ...
146k 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 ...
265k 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 ...
166k 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'
185k 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)...
364k 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, ...
349k 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?
263k views

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?
247k 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 ...
116k 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 ?
224k views

225k 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 (...
230k 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 ...
121k 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 ...
185k 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 ...
187k 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 ...
142k 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?
197k 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 ...
105k views

### What is the reverse recovery time in a diode?

What is the reverse recovery time in a diode?
345k 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 ....
206k 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....
137k 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?
68k 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 ...
168k 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 ...
196k 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 ...
133k 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 ...
122k 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 ...
250k 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 ...
109k 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 ...
201k 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 ...
79k 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 ...
85k 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.
125k 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 ...
128k 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 ...
158k views

### LED bulb still emits light when turned off

I have recently purchased an IKEA LED bulb with G9 fittings, to replace a halogen one. This one. The bulb is installed in a lamp with 3 other halogen G9s in a 3 + 1 configuration with a 3-state ...