All Questions
Tagged with resistance dc
42
questions
1
vote
3
answers
121
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
views
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
views
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
479
views
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 ...
- 11
19
votes
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, ...
- 9,876
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
289
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
539
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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
663
views
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
161
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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
views
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
570
views
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