All Questions
10
questions
0
votes
3
answers
374
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Current limiting or voltage dropping [duplicate]
I was trying to understand the usage for the word "current limiting resistor." Taking an example of a simple LED with a resistor in series, the way I understand this is we are trying to ...
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-2
votes
5
answers
2k
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Why can't we light up 4x 3V leds with a 12V power supply?
To calculate the resistor to limit the current, if we use R=P/I² formula, it gives us wrong parameters rather than using V=RxI, so the 12V-12V is 0 and the P formula gives us nothing.
Why is it so?
1
vote
3
answers
2k
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Hi! I would like to connect my LED lights (Vaxmyra from IKEA) designed for 24V system into my 12V system, do I need a current limiting resistor?
I bought these VAXMYRA LEDs thinking they were made for 12V but apparently they need to be feeded 24V.
Supposedly I'll have to install a 24V DC step-up converter, but this device can deliver up to 3A ...
0
votes
1
answer
117
views
How to measure and power an array of unknown RGB LEDs?
I have 5 of these plastic moldings that each have 2 RGB LEDs inside along with a microcontroller that rotates through the color spectrum for aesthetics. I want to bypass the microcontroller so that I ...
- 105
0
votes
3
answers
849
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How to solve for current given resistor value for LED circuit?
So I have the following LED circuit:
I know how to find the forward voltage and current from the datasheet of the LED and how to then solve for the appropriate value of \$R\$.
However, what I really ...
- 171
0
votes
1
answer
475
views
Ned help modifying a Harbor Freight LED flashlight into a light source for a microscope
I have a couple of Harbor Freight free-when-you-buy-something-else flashlights.
I want to modify one of them into a light source for a microscope. I've taken (10) of the (24) white LEDs off of one ...
0
votes
1
answer
121
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Why is the current wrong after resistors in series with simple LED?
Setup
source --- 1.5V batteries x2 = 3V
LED --- 2V 35mA http://www.futurlec.com/LED/LED5R.shtml
Resistors --- CR1W 1W 10ohm +-5% x 4 = 40ohm
Description
I have your average "Light up a LED" ...
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0
votes
1
answer
445
views
Current Limiting Resistors for Multi-Branch LED circuit
I have bought some of the following LEDs (going to try either for brightness/size):
100 Pcs 0603 SMD Superbright LED Yellow Light Emitting Diodes
40 Pcs SMD 1206 LED Lamp Yellow Light Emitting Diodes
...
- 105
0
votes
2
answers
586
views
Is resistor on LED's necessary after voltage drop?
Let's say we have perfect 5V DC 0.1A power supply. Obviously for one LED we would need a resistor (I'm well aware of Ohm's law), BUT what if we connect bunch of LED's in series. And the current drain ...
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3
votes
2
answers
773
views
What's the difference of placing multiple resistors and one resistor for limiting the current of LEDs?
I'm looking at a diagram and wondering if I could use just one resistor to limit the current of the LEDs instead of multiple resistors so that the cathodes are all connected to the same resistor.
JL
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