All Questions
Tagged with current-limiting led
60
questions
0
votes
4
answers
2k
views
How to increase the current in this circuit?
Im trying to build a circuit to send information using IR led, using pulse signals (Im trying to mimic a home appliance remote control).
My leds (datasheet) operate at 1.3V, and their maximum pulse ...
- 227
0
votes
1
answer
596
views
Driving a 5V IR led with a 5V charger?
I'm trying to build a remote control with IR led.
I'm experiencing low range with my 1.5V, If=50mA IR leds, so I looked for and found a 5V, If=100mA IR leds.
twice the current, hence probably better ...
- 227
0
votes
2
answers
200
views
Given Vf across a LED, what is the current draw?
I have sourced some LEDs from everyone's favorite high-quality electronics marketplace, eBay.
I have a simplistic "datasheet" for the 7-segment LEDs that I purchased, which show a Vf of 3.8v across ...
- 103
0
votes
2
answers
304
views
If I drive an LED whose forward voltage is 2V with a source that's 3.3V limited to 20ma, will I harm the LED?
Background: I built a 10x20 LED matrix for use inside a jack-o-lantern. The matrix is driven by 74HC595 shift registers that are connected to an Arduino.
I've attached the Vcc of the shift registers ...
- 782
0
votes
2
answers
203
views
Limit current with fewer resistors
Arduino digital pin in OUTPUT mode have low impedance, is it safe to limit current through two leds (connected to two output pins) with one resistor, not two (knowing that leds will go dim and current ...
- 125
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 ...
- 37
0
votes
2
answers
136
views
Forward current for assorted LEDs
I have an assortment of T1 and T1¾ LEDs from sampler kits and beginner kits. The kits have sketchy documentation, with missing or inaccurate part numbers. I was able to track down datasheets for some ...
- 141
1
vote
3
answers
364
views
User power supply current limit to avoid current limiting resistors for LED
everyone!
I would like to know if I can avoid to use current limiting resistors by pushing my power supply to its limits (it already sounds not like a good idea... btw...).
Say I have a 3.3V power ...
- 167
1
vote
2
answers
3k
views
Limit drawn current but not voltage (LED driver for 100W LED)
So I have serial connected 8 LiPo's with corresponding controllers to monitor the battery pack. Now, they deliver 32 volts which is precisely what I need but they deliver way to much amperage compared ...
- 183
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
- 51
2
votes
3
answers
889
views
Diode drop vs open drain output tolerance
I have an LED Driver IC that states a 5.5 V tolerant open drain output. It's Absolute Maximum section indicates 6.5 V with a note saying "The input negative-voltage and output voltage ratings may ...
- 73.2k
4
votes
1
answer
7k
views
Need help calculating resistor values for IR LED Driver
I'm wiring an IR LED driver for an Arduino project I'm prototyping.
The Arduino will be run at 5V, and I'm planning on using it's 5V output to drive the transistor that runs the LED
The circuit I've ...
- 1,418
5
votes
3
answers
2k
views
Do I need a current limiting resistor when powering an LED below its forward voltage?
I've reviewed the questions:
Why can you use an LED below voltage?
Is a current-limiting resistor required for LEDs if the forward voltage and supply voltage are equal?
But combining them begs ...
- 34.3k
10
votes
4
answers
11k
views
Why is LED lighting up despite Supply voltage < Forward voltage
I have an LED which has specified Typical forward voltage of 3.5V and Maximum forward voltage 3.9V.
I applied 3.3V across it with a 300 Ohm resistor in series. Why did it light up?
I am wondering if ...
- 4,942
42
votes
2
answers
22k
views
Correct formula for LED current-limiting resistor?
I'm trying to work out what value resistor to use in a LED circuit. The equation I'd use to do this is:
$$ R = \frac{V_{cc} - V_f}{I_f} $$
Seems logical, and makes complete sense. The answers to the ...
- 1,092