Questions tagged [electrical]

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24
votes
3answers
4k views

Why solder mask are not applied to RF PCBs

I've gone through some of the RF PCB designs. In which solder masking on the traces are not present. Like this one Is there a specific reason or performance issue to remove that?
19
votes
10answers
7k views

Are all electrical sockets of my house in the same phase?

Most countries use AC power that is supplied to each house. This AC power is in the form of a sine wave. Suppose I have 2 electrical power sockets in two rooms that are at the opposite ends of my ...
18
votes
7answers
4k views

Staying in Phase On The Grid

I have been an EE for over forty years and never did find out the right answer to this one.... How do power-stations and transformer switching stations ensure that the power they are feeding into the ...
14
votes
3answers
2k views

Standard Volt and Ampere

A recent question on here asking about how to calculate the accuracy of a circuit got me thinking about calibration in general. In particular, as EEs we routinely use volts and amperes as a unit and ...
12
votes
1answer
4k views

Symbols: Double-arrow circle enclosed “10” on electronic appliances

What does the symbol that says 10 inside the double arrowed circle mean? I have seen a similar symbol on another appliance that had the number 25
11
votes
2answers
1k views

Is it a good idea to connect a line buffer to ground?

Got a quick question. I'm dealing with 74VHC125BQ,115 and I won't be using one of the line drivers; the rest are connected to UART. So, I'm wondering what I should do with the last one. Is it a good ...
10
votes
2answers
3k views

Why does the current not skip resistors R3 and R5 when R6 and R4 have no resistance?

I do not understand why the current still flows through resistors R3 and R5 when R6 and R4's resistance is 0. To me, it would seem that the current would skip R3 and R5, however the answer key says ...
9
votes
2answers
2k views

What property of a BJT transistor makes it an amplifier?

I know how we can amplify a given signal using BJT transistors by biasing them. But I would like to know what is that crux property which enables BJT transistor to act like an amplifier. Is it the ...
8
votes
2answers
1k views

Phasing Order in IEC Color Codes

Currently, IEC 60445 international standard is used for conductor terminal color identifications. I've obtained different versions of the standard (2017 being the latest) and also IEC 60446, which was ...
7
votes
8answers
880 views

Bulbs on seperate circuits triggering third bulb

I would like to know if the following is possible, and if it is possible, roughly how the wiring should be done ... I have 2 light bulbs (BULB1 and BULB2) connected to SEPERATE switches. I want to ...
7
votes
2answers
6k views

Capacitor Bank Rating

I need to know why capacitor banks are rated in KVAr rather than Farads? Suppose I have one capacitor bank of 10kVAr which is for a rated voltage of 400V. Will this bank provide the same reactive ...
6
votes
1answer
4k views

Can't find this electrical symbol

What is the name of this device?
6
votes
3answers
2k views

Operating principles of a sawtooth wave generator bootstrap circuit

In one of my assignments, I was asked to explain the working principles of the sawtooth wave generator shown below. The input voltage is a spiked waveform obtained from a differentiator circuit. I ...
6
votes
1answer
115 views

Hair dryer fuse too low for spec power?

So I'm tearing down this hair dryer for a school project where I need to make it have variable heat and variable motor speed which can be controlled through an Arduino. I'm currently looking at where ...
5
votes
10answers
1k views

Film/TV question: How to build Foam Cutter from only household items

I'm writing a scene for television and I need to make a foam/rope cutter from household items. I've watched several videos, including this one: https://www.youtube.com/watch?v=cM0lP2WCzY0, and ...
5
votes
3answers
555 views

Hybrid gas electric drone

I have a nitro engine that’s idling at 1600 RPM. As the title says , I also have a BLDC coupled directly to the nitro engine working as a generator. That generator is capable of producing 3.5kW of ...
5
votes
2answers
866 views

Bulding a physical calculator from scratch [duplicate]

As you can probably tell I am relatively new to the electronics scene and I'm rather stuck on a project I'm doing for school. I am on my second year of an Electrical engineering degree, tasked to do ...
5
votes
1answer
184 views

I purchased a few of these units and have no idea what they are. Is there anyone that might have some suggestions?

The item measures 1" wide and 1-1/4" high nad about 1/2" front to back
4
votes
5answers
1k views

What is the best way to convert a 10V power supply into a 5V power supply?

If you were given a 10V power supply and wanted to power USB devices with it, how would you convert it to 5V? Would using a voltage divider splitting it into 2 5V lines be the best? What ohm resistors ...
4
votes
3answers
1k views

Does current have a physical effect on wire?

Does current have an effect on the wire it moves through? I think I heard somewhere that over time small wires in CPUs can move because of the current going through them. If it is a thing what's the ...
4
votes
1answer
667 views

Would the motor reverse if phases swapped for this case?

A servomotor power connection pins are given as follows: U V W are the three phase terminals. Would the motor reverse if I mistakenly swap phases U and V namely if I connect pin 1 to W and pin 3 to U?...
4
votes
2answers
723 views

Capacitor and inductor working principle

I want to know that there is opposition mechanism of current in inductor say back emf than what is opposition mechanism of voltage in capacitor ??? And also want to know that when inductor suddenly ...
4
votes
4answers
956 views

What is a ground fault?

Is this different to a short circuit and if so then how? Because some circuit breaker protect from both short circuits and ground fault thanks, so when do u need to protect from them and when don’t ...
4
votes
1answer
848 views

What is wrong with this soldering iron?

It's body is blackened, just after 5 minutes of heating and it's body is also bent. How can I solder when the iron itself works so poorly? P.S: I am using it for the first time.
4
votes
2answers
155 views

How do you differentiate between rms and peak voltage?

In the circuit above I've been asked to calculate the average power absorbed by the 10 Ω resistor. I managed to calculate a value for \$V_0=40\sqrt2\,\angle{-25}\$. But I'm not sure if this is peak ...
4
votes
5answers
252 views

Grounding conductor meant to protect electrical devices?

I had a home inspection performed on an old house recently. The inspector noticed that some of the outlets had an unconnected third prong. He told me that the absence of a grounding conductor on the ...
4
votes
5answers
320 views

If ground and neutral are bonded at main panel, why aren't all grounded device chassis energized?

I know this is a question with variants that have been asked countless times on the internet and on this site. Believe me that I have scoured through these questions and answers in search for a ...
4
votes
1answer
2k views

MOSFET: How can I find conduction parameter and transconductance based on graphs?

So I have my graphs (below) with various MOSFET characteristics. I don't know device dimensions or geometry, therefore I can't solve for the 2 directly with an equation. Otherwise I would just do that....
4
votes
2answers
700 views

Calculating total torque of stepper motor to lift and rotate some weight

I am going to design a system that would be control remotely. The system consist of stepper motor and solid cylinder rod of about 30 inches long and needs to lift about 0.5 lb/0.223 kg mean up to 90\$^...
3
votes
2answers
3k views

Are there gate-level ways to produce the min or max of two binary values?

Some basics of digital logic are the half-adder and full-adder. We know how to produce the sum of two binary values at the level of AND/OR/NOT gates, in a straightforward way presented in many ...
3
votes
1answer
200 views

What symbol is this?

Does anyone know what this step between the two lines mean?
3
votes
1answer
280 views

Giant pogo pin or spring probe pin for registration during electrical test

Solved: if you search for "GP-2 PCB Board Umbrella Shape 5.3mm Tip Testing Probe Pins Receptacles" you will find these probes! Thanks for the help! I am designing an electrical test fixture, and I ...
3
votes
1answer
106 views

Create my own battery for my electric bike [closed]

I was wondering if it's possible to avoid buying a $400 48V 15Ah battery with an output of 54.6V and 2A, and instead make one by joining multiple 3.7V 5Ah batteries in series and or in parallel? Is a ...
3
votes
1answer
74 views

Is it safe to bundle together 380V cable + 24V signal cable + network cable?

I have the following cables between two machines: 380V 3-phase power cable 24V signal cable EtherCAT cable I would like to create an interface using a modular connector such as the one in the ...
3
votes
2answers
187 views

Is this a good design for a 0…7 counter?

My daughter's electronics teacher recommends to realize a counter from 0...7 as follows: It shall give an output pulse (for a subsequent circuit) when the button is hit the 8-th time. For me this ...
3
votes
1answer
488 views

VA rating of Wall receptacle

What does VA rating of a wall receptacle means ? Just started using Revit for Electrical Design (120V/208V) and came across wall receptacle rated as 180 VA. Just trying to wrap my head around that ...
2
votes
4answers
2k views

Voltage Drop Calculation (AC)

Hope someone can help me out and point me the right direction to solving this. I am trying to do a voltage drop calculation to see the VD % for the cable selected. The following are the values, ...
2
votes
3answers
500 views

How to figure out what resistors are in the E12 and E24 series?

Is there a way, other then remembering, to figure out what resistors are in both of these series?
2
votes
4answers
133 views
2
votes
1answer
291 views

Will resistance of wire increase with age due to some effects?

Today I had an electrical problem at my home not yet resolved. I will explain the problem. The switch for water motor and switch for lamp are nearby in same board. When I turn ON the lamp switch, the ...
2
votes
2answers
380 views

How do designers know about kilowatt power of wind turbine generators like 1.5 MW?

Generators and transformers are always designed in kVA because designers never know about the load it will provide power to. Then how do we know the wind turbine generator will deliver 1500 kW or 2 MW ...
2
votes
1answer
97 views

Does cutting the covering of subwoofer wire affect the sound quality?

I have Sony 5.1 channel sound system. There is some cut on covering of subwoofer wire. The copper wire is not affected at all. So, I am curious to know whether it will leak the passage of sound and ...
2
votes
3answers
2k views

Safe use of Coiled Cable [duplicate]

So we have this machine at work, a strapping machine, and it has a long power lead which is left loose on the ground, and it's getting gradually destroyed - accident waiting to happen. I know that ...
2
votes
2answers
64 views

How to select a Relay that can handle a load of 42V, 3A DC?

I want a relay that can be controlled by a Raspberry Pi and can handle a load up to 42V and 3A DC. I was looking at this: relay which is rated at DC 30V/10A. Although, 30V is less than 42V but I was ...
2
votes
2answers
165 views

What is the air gap area?

I found in a book the air gap area is \$Ag= (W+l_g)*(d+l_g)\$ However, I know therectangular prism is \$A=2*(w*d+d*lg+w*lg)\$. Could any one please help me what they have air gap equals \$Ag= (W+l_g)...
2
votes
1answer
383 views

what is exactly 'gain and loss' is and how is it used?

I'm kinda confused by its definition. I know that gain is a measurement and gain and loss is the calculation (??). I'm still in 12th grade. Please guide me.
2
votes
2answers
3k views

Where does branch circuit neutral current go in a single phase or three phase electrical panel?

Specifically, I would like to know the exact path of travel for the neutral current when it comes back from a load to the electrical panel. I am an electrician of 20 years and have recently acquired ...
2
votes
2answers
3k views

How to mitigate voltage spikes when turning car ON?

I need to connect some things (LEDs and other misc.) to the 12V rail in a car. I understand that this rail gets a beefy ~100V spike on ignition. I have also heard that the battery soaks this spike (...
2
votes
3answers
546 views

Reduce/Remove Sparks in AC and DC Contacts of Relays

I see that there are sparks being generated whenever there is a connection established between two contact points in the relays. So is there a way to reduce/remove those spark generated in the relays.
2
votes
4answers
106 views

Generator to home wiring

I live in South Florida an as such need to have generators for hurricanes. I have 2 Generators, a small 3300 Watt Inverter and a big loud 9000 Watt generators. Edit: My plan is to use only 1 ...

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