Questions tagged [current-rating]

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If a device is rated at 12 V/80 mA what does that mean as far as the length of time that it will draw 80 mA?

I have an electromagnetic device designed to hold a fire door open until either the circuit is cut or the building's electrical supply goes out. At which point the door is released and will close. It ...
0
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1answer
58 views

What factors do I need to consider when selecting an inductor to use in a circuit with the MT3608?

I am trying to use the MT3608 chip to boost the power output of a 3.7V lipo battery from 3.7V to 5V, which will ultimately power an ATMEGA32U4 chip. Below is a picture of my circuit where I have ...
3
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2answers
583 views

Potentiometer overheating - is it due to current rating?

I need to get a pump running at different speeds so I ordered an electric motor, a potentiometer and a power supply adapter. I put them all together and they worked, however the potentiometer got ...
1
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2answers
227 views

Current Rating of a device (how does this change when changing the voltage)

Let's say you have a device that is rated at the following: 550 amps @ 12Vdc (heat) Max Voltage = 48Vdc (insulation material max voltage rating) I am mainly concerned with the heat, we could ...
0
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2answers
86 views

What could be the output current rating of the following shunt regulator?

I am trying to solve the 2013 paper set by ISRO for electrical engineers. I wanted to verify if my answer to Question no 18 is correct. So \$I_L\$ is being drawn out of the circuit shown. Since the ...
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2answers
134 views

Current rating for busbars

How does one go about calculating the current rating of self produced busbars? Store bought wires are a lot easier, as they have the derating factors for parallel wires and ambient temperature readily ...
0
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1answer
32 views

Does Switch current rating matters if its connected to ground wire

I am designing a pcb with an SMD switch. Usually my circuit needs 200mA peak current. But I am putting a 25mA rated switch on the ground line. Now according to my knowledge if I was placing this ...
0
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2answers
128 views

Less voltage more amp? switch characteristis [duplicate]

I have a question regarding switches, relays etc Ex, if I have a switch rated for 24v 0.5a, can the contacts then safely handle 12v up to 1a? Because the power passing the switch is the same? Or ...
1
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2answers
318 views

How to guess voltage ratings and current ratings in capacitor and inductor?

I have a list of values of capacitors and i also know their material types! But i don't know how to figure out their voltage rating? "Ratings have been removed in the capacitors for this purpose" ...
0
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1answer
321 views

Does a VSR current rating affect the size of leisure batteries that it can charge?

(Apologies if this is a silly question, I don't do much electronics.) I'm converting a van into a camper. I've bought three 12V 95Ah AGM batteries (which, incidentally, will be hooked up to a solar ...
5
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1answer
1k views

Why do the normally closed and normally open relay contacts have different current ratings?

Please refer to the image below: Taken from the datasheet: http://www.songchuan.com/db/pictures/AdminModules/PDT/PDT090410001/201191913495127935.pdf
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1answer
2k views

How to find step down transformer secondary output current rating?

I have obtained a small transformer with 7 windings, a 220V and 6 other individually isolated low voltages. How can I find out the current rating for the lower voltage windings? I was told these used ...
4
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4answers
4k views

How to determine the nominal current of an LED?

I salvaged the LED disk from a defunct LED light bulb. (The problem was an arced transformer, the LEDs are intact.) It has several unmarked white SMD LEDs soldered on it: 5 lines parallel, with 3 LEDs ...
0
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0answers
452 views

Can a 12V 7AH@ C20 battery support a motor having load variations form 1-10 Amps?

I want to know what is the significance of C5, C10, C20 rated 7AH Battery to drive a varying load 12V DC Motor. Is it possible for a C20 Battery to power the motor for atleast 20Mins or so if the ...
2
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1answer
399 views

How to calculate the maximum current rating of an ammeter manganin shunt?

I want to make a shunt for an ammeter using a manganin wire. I don't know how to chose the wire diameter for the desired current. For example, my shunt will have 0.05 ohms and it must withstand 5A for ...
2
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5answers
2k views

Why do some wire gauge ampacity charts state vastly different current ratings?

This is a question that I've had for a while but have somehow managed to go without asking. Looking at all the wire gauge ampacity charts online, some of them appear to provide vastly different ...