A well known relationship that describes the relationship between Voltage and current through a device's resistance expressed mathematically as V= IR. This formula says that voltage across the device is equal to the current through the device multiplied by the resistance.
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177 views
basic math question about voltage, ohms, resistance
total n00b here. After working on several projects by copy & paste from other people's schematics and code, I'm finally digging in and learning some of the math to know what I'm doing.
If I have ...
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4answers
844 views
Why do LEDs not obey Ohm's law?
In a previous question, it was brought to me that LEDs do not obey the Ohm's law.
(See Calculate expected voltage around a resistor)
Simply put: how is that?
What makes them behave so differently? ...
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3answers
141 views
Calculate expected voltage around a resistor [duplicate]
It's been a few years since I first studied the Ohm's law at school.
Now I'm really getting into electronics, and I must admit a part of it still puzzles me.
I know this is kind of a strange ...
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3answers
107 views
How is current lowered as Voltage is increased in AC power transmission
I was reading about power transmission on wikipedia and came across the explanation of the efficiency of AC power transmission that said power in the load = (I^2)* R while power transmitted= IV. The ...
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2answers
88 views
Voltage distribution between components
I often see the same method for computing voltage distribution in electronic circuits implying components whose V-I curves are not trivial.
For example, in a circuit implying a resistor and a LED ...
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0answers
46 views
What should the values of resistors R1-R6 be in order to get desired voltage pulse specified in Allegro A1362's data sheet?
I am trying to program sensitivity and offset of the A1362 Hall-Effect Sensor
by sending the following voltage pulses
VpH - Voltage High - 27 Volts
VpM - Voltage Mid - 15 Volts
VpL - Voltage Low - 3 ...
6
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3answers
368 views
Why do diodes have a voltage drop?
Is resistance what makes a diode have a voltage drop?
Or is it impedence?
If it is electrical energy being converted to light, please tell me what this effect is called.
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2answers
161 views
Maximum power for Arduino Monster Moto Shield
I'm reading the specs for the SparkFun Monster Moto shield which specifies that
Max Voltage is 16V
Maximum Current 30A
Given Ohm's law, does that mean that the maximum power is 480 watts? That ...
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1answer
203 views
Should I use a resistor in this scenario?
I am building a IR pen and wondering if I need a resistor for this. Here is my specifications for my IR LED:
Forward Voltage: 1.2 V
Forward Current 100 mA
So on and so on. I am powering it with a ...
1
vote
1answer
96 views
How to prevent a resistor receiving a too high power?
If a circuit was creating 0.3 watts, and resistors rated for 1/4 watts were used, what would be the easiest way to make it stay inside the rating? Would it be to, say, connect two resistors of twice ...
2
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2answers
205 views
A christmas light bulb question
This may look like a homework, but it's not. Actually it is related to Christmas. My Chrismas lights in front of the house are constructed from segments. Each segment consists of 16 incandescent light ...
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3answers
127 views
Reading datasheets and applying Ohm's Law
I have a CPLD that wants +3.3v and has a maximum allowable current per pin of 8ma. I need to supply a clock signal. The oscillator I selected accepts 5v and outputs 5v-ish levels. I'm finding it ...
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3answers
271 views
LED current limiting resistor and Ohm's Law
Yesterday I was trying to figure out how many ohms of resistor should I be using for my LED, and found this post right here in the forum.
The formula states that one should subtract the voltage drop ...
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1answer
119 views
Triac datasheet values
I have a Triac that I want to use to control low voltage (~16 V) AC. The data sheet is found here. It specifies that the peak gate voltage is 5 V with a peak current rating of 2 A (which seems quite ...
6
votes
4answers
2k views
How do I calculate the necessary resistance for a voltage divider?
I’m self-taught, and this is a little bit of a thought experiment for me to understand Ohm’s Law better.
I have a very simple voltage divider. Given a 15V DC input, each of three 4.7KΩ resistors ...
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2answers
2k views
Potential difference across one resistor with and without a known current?
Okay imagine you have a voltage supply of 10V and one Resistor of 5 Ohms.
Now find the current : I=5/10 = 0.5A
So potential difference across that resistor : V=IR=10V .. which proves this statement ...
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4answers
326 views
Sharing a pull-up resistor
I have two IC chips. On one chip I have one 10K ohm pull-up resistor and on another chip I have three 10K ohm pull-up resistors.
At first I was using four through hole pull-up resistors. Then I ...
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1answer
264 views
How to choose correct resistor with proper wattage and ohms for 6 leds connected in a serial circuit?
Let's suppose I've six LED lights with each 3.2 Volt and 20mA and all six of them are connected in one serial circuit. I know there is better setup but for this I'm using this circuit setup.
I'm ...
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1answer
2k views
How to calculate current and voltage draw of a single resistor circuit?
If I have a single 270 ohm resistor connected in a circuit to a 3.3V 50mA power supply, how can I measure the voltage and current for the resistor? I'm familiar with Ohm's law V=IR, where V is the ...
1
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3answers
246 views
Finding the current flowing in parallel circuit
Lets say we have a circuit with a voltage source and a 5 ohm resistor. The voltage source is 20 v and so the current flowing is 4 amperes (according to ohms law). Now, we add a short wire in parallel ...
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5answers
3k views
Why do we need resistors in led
I've researched and it says that resistors limit the current flowing through the LED.
But this statement confuses me because we know that in a series circuit, the current is constant at every point, ...
