All Questions
Tagged with resistance dc
42
questions
1
vote
3
answers
122
views
Calculate resistance between 1 and 2
I am preparing for an electrical engineering exam coming up and I got stuck on task C, where you have to determine the resistance between 1 and 2. How do you do that exactly?
I have already solved ...
- 53
1
vote
1
answer
145
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Unstable to do resistance measurements due to electric fans
I built a small system to monitor wood drying. The idea is to turn on exhaust or circulation fans (230V-AC) based on the absolute humidity and ambient temperature (respectively) of a small drying ...
- 141
1
vote
5
answers
98
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Measuring power in AC
I have a heater running at 240VAC. I'm trying to measure the power by datalogging the voltage and current then multiply both inorder to get the power reading.
I know that this method works well with ...
- 19
1
vote
1
answer
484
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Mimic a thermistor/variable resistance signal using PWM
I am looking for a way to create a variable resistance signal to mimic the signal that would typically be provided by a thermistor, but by using a digital signal that switches to ground.
I currently ...
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19
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3
answers
5k
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Why does the resistance of a space heater decrease as it gets hot?
I came across something I find odd while hacking a space heater into a high power dummy load: my cheap space heater is rated 1.5 kW 110 VAC, so I expected to see less than 8 ohms which, when heating, ...
- 9,906
0
votes
1
answer
1k
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How does a relay behave when its resistance is increased or decreased? [closed]
I have a relay of coil resistance 200 ohm whose input voltage is 12V DC.
Now, under the same 12V DC supply, will the relay be activated when:
The relay coil is decreased, say by 100 ohm i.e. new coil ...
- 63
0
votes
1
answer
290
views
How to calculate for the voltage across resistor R4 and R6 using the operating point values? [closed]
This is the schematic diagram for the circuit that I need to solve. All I need to know is if it is possible to solve for the voltage across resistor r4 and r6 with all the given operating point values....
0
votes
1
answer
545
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Why does the resistance of a brushed Dc motor from an experiment kit vary?
I am currently performing an experiment in which I measure the Current and Voltage of a motor that experiences changes in load. I am using a 3V (3V battery) supply however the voltmeter's (connected ...
0
votes
2
answers
4k
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Derivation of formula for temperature coefficient of resistance
https://www.electrical4u.com/temperature-coefficient-of-resistance/
Referring to this article, I'd like to compile two key formulas for the temperature coefficient of resistance.
First is the formula ...
- 469
0
votes
1
answer
665
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What is the meaning of inferred absolute zero temperature? Why does the resistance temperature graph it is obtained from behave that way?
Studying basic direct current circuits, I've come across the term inferred absolute zero temperature on computation of resistances that change due to temperature. Based on my readings, I understand it ...
- 469
0
votes
0
answers
163
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Need to move a 12v DC, 1.5 ohm resistance circuit (power window motor) into another vehicle with a .8 ohm motor
In the past, when I have tried to cut down the voltage from a variable solar panel into a DC motor with a 10 watt resistor, the resistor always got too hot.
This case is a somewhat different; a solid ...
- 11
0
votes
1
answer
2k
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Value of resistor to limit current to 1 ampere in 12 volts circuit
I want to connect my modem directly to a 12volt battery so that I dont need a adapter. My modem’s specs says that it need 12 volt 1 ampere as input.Now the voltage of 12 volts can be directly given by ...
- 39
0
votes
4
answers
571
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I thought I understood the basics of DC circuits and Ohm's law but now I'm confused [closed]
So I was taught in school and also read a lot of articles of the basics of DC circuits. I know the formula R=V/I, and therefore that resistance is directly proportional to voltage and inversely ...
- 19
0
votes
1
answer
44
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Thevenin Resistance query
I have an amplifier model circuit where I've determined the load (speaker) voltage (using its peak power output and its resistance) and measured the open-circuit voltage.
How can I work out the ...
- 23
1
vote
2
answers
68
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trying to get motor to turn on
i'm very new to electronics and working thru an udemy course on an introduction to electronics.
I'm trying to get this air pump to activate in a simple DC circuit on a breadboard.
https://www.ebay....
- 115
0
votes
2
answers
2k
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Multimeter not picking up a resistance
I am making a set of speakers using 34.5 AWG magnet wire, and neodymium magnets to make a voice coil.
For my wire gauge and required length I should have ~3 Ω (DC), 4 Ω (AC).
The issue is when I ...
-2
votes
2
answers
352
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How to remove 50 Hz, 100mV noise? [closed]
I am getting 100 mV noise signal at 50 Hz. I do not know the origin of the noise. What should I need to do to remove it?
- 69
1
vote
1
answer
145
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Resistors in series and parallel conundrum
Three resistors of some resistance (ohms) are put in series and the measured total resistance is 24 ohm. Now, if the same three resistors are connected in parallel to each other and the total ...
- 13
0
votes
1
answer
2k
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Power absorbed by load resistor
Can someone double-check where's the mistake? The system didn't accept my answer.
TASK: Find the maximum power absorbed by the load resistor, knowing that:
$$E = 6.6V; R_{1} = 12.1Ω; R_{2} = 14Ω; R_{...
- 179
11
votes
7
answers
2k
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Is there any difference between transferring DC over one 36 mm² wire or six 6 mm² wires?
I am designing an off-grid DIY solar power site where the distance between the solar panels and inverter is going to be several dozen meters, so I would prefer to put a thicker wire to minimize losses....
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0
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3
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7k
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Where is the resistance in a starter motor circuit?
In a car or motorcycle, the starter motor is switched by a relay. The relay coil is switched by a key switch or small pushbutton. All of it is a 12 volt DC system.
Is it correct to think of the relay ...
- 103
4
votes
2
answers
1k
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Why do batteries only have resistance one way?
I initially had this question because I was playing around with brine electrolysis and I found that the resistance is 0 one way (positive in negative cell) and infinite the other way (positive in ...
- 59
1
vote
1
answer
868
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Tapping into a 4 AWG wire
I am part of a hobby project where we have a pair of fat, insulated #4 AWG stranded copper wires carrying +5V and ground. I want to tap into these wires every few inches to draw power off it (max draw ...
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-1
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2
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303
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i have a question about the analogy between Hydraulic system and Electrical system
In Hydraulic system the Pump out oil "" flow "" , It doesn't out pressure , well what create the pressure is the " restriction " or "" orifice "" or "" resistance "" .
In Electrical system , The ...
- 1
1
vote
2
answers
112
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Resistance of electronic circuits
I am currently trying to build a Regulated DC Power Supply for an electronic piano. I am trying to find the minimum capacitance that I need to able to reach the desired ripple voltage. To find my ...
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2
votes
2
answers
10k
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Is the resistance in a DC Motor constant if the voltage is?
Is resistance in a DC motor constant if both the load and voltage are constant as well?
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0
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2
answers
1k
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Calculated resistance of an LED [duplicate]
I am working on some circuit lab homework this week and am a bit stumped by something I just can't seem to find anywhere in my Circuit Analysis I book.
The lab has me construct the following circuit ...
-2
votes
2
answers
344
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Problem with resistance,electric circuit etc. etc.
In which way a resistance is to be connected with a bulb labelled 120W-60V when it is connected with 220V DC source so that maximum illumination with proper security is maintained? What is the ...
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-2
votes
1
answer
700
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is it possible to connect ac power source to battery in parallel connection ?
Is it possible to connect ac power source & a battery in a parallel connection where a battery is low voltage & have current more then the internal resistance of circuit ?
As the battery is ...
- 1
0
votes
2
answers
963
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Calculating voltage in a simple circuit
If I had a 12V battery and wanted to use an LED that used 2V and 20mA, then I need a resistor that will drop 10V and provide enough resistance to produce a current of 20mA.
Therefore I would use R=V/I ...
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