All Questions
Tagged with current-limiting led
60
questions
2
votes
2
answers
113
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TPS2553 Current limiting for RGB LEDs
I'm building a keyboard which will use SK6803 mini-e LEDs (ws2812 driver). I'm using a Pi Pico and as such the USB limit for current draw is ~500mA. I'm looking to limit the current draw from the LEDs ...
- 31
0
votes
0
answers
53
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TPS2553 Current limiting [closed]
Editing this so it can be deleted for double post reasons.
I'm building a keyboard which will use SK6803 mini-e LEDs (ws2812 driver). I'm using a Pi Pico and as such the USB limit for current draw is ~...
- 31
0
votes
0
answers
67
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LEDs without resistors in parallel circuit
I have connected 75 WS2812B LEDs in parallel circuit as shown in manufacturer's datasheet:
Source: https://www.tme.eu/Document/64e8d425b90f84990264129a9679149c/WS2812B-V5.pdf
Since all LEDs should ...
- 131
0
votes
1
answer
70
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50 watt high-power LED current problem [duplicate]
I am using this 50 watt high power LED:
.
And want to power it using this voltage booster:
From 12 V to 34 V as the requirements of the LED datasheet.
Will it work?
I read that I need to limit the ...
0
votes
2
answers
867
views
Calculating current limiting resistor for high current circuits
I am designing a simple three-phase inverter to begin working in power electronics. I have no experience in power electronics and minor experience designing circuits. While working on it, I ...
- 117
1
vote
1
answer
551
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Efficient and cost-effective way to limit current across an LED strip
I am currently attempting to build a DIY driver board to power the backlight of an LM270WQ1 panel.
Per the datasheet, there are six LED strips, each of which take 36V @ 350mA.
The adapter board that ...
0
votes
2
answers
166
views
Why is my BJT current control circuit not controlling current?
I have built this circuit (except the Re I bought came out to Re = 0.21 ohms after measuring it, so I used Rin = 680 ohms and R1 = 18k) to control current through eight of these LEDs using this BJT.
...
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0
votes
1
answer
86
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How to limit power to LED, efficiently
I am looking to use a 12V, 5 ampere car battery on a small 5V, 2A LED. Typical applications online use a resistor or voltage regulator, but since I am using a battery I would like to conserve power, ...
- 239
-1
votes
2
answers
131
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Led strip and relay current splitting?
I have a 12 V LED strip that works at 10 W. I want it to run at multiple current configurations with two relays and without the help of a microcontroller. I am attaching a diagram of my intended setup....
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1
vote
1
answer
68
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LED strip light power
I am looking at using small lengths of single colour 12v LED strip (2835) in a project, maybe just 1 or two sections i.e. 3 or 6 LED's. I have tried single 2 pin LED's and they aren't bright enough.
...
- 11
0
votes
3
answers
839
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How can I figure out what the forward current and forward voltage will be for an LED given a resistor size
We're trying to order some boards from our PCBA manufacturer but they're having trouble sourcing our original LEDs (QBLP601-IW). They proposed an alternative LED (LSM0603443V) and I'm trying to be ...
- 626
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 ...
- 1
0
votes
2
answers
360
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Safe to use series resistors for powering common anode RGB LED from single constant current source?
I have a 3-9W common anode RGB LED (https://cdn-shop.adafruit.com/product-files/2524/FD-9RGB-Y2.pdf) and want to vary each leg's voltage with PWM through FETs, namely IRLZ44Ns, and an Arduino, in a ...
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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?
3
votes
2
answers
102
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Boosting load current of voltage regulator
I'm trying to connect little 3v LEDs to a motorcycle's alternator and i want to regulate the voltage of it to 3 volts so the LEDs don't burn up
the alternator gives off 2.5 volts and over with 3 amps ...
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 ...
3
votes
2
answers
601
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LED fairy lights with series capacitor?
I've opened up the battery box of a string of fairy lights (like pictured at bottom) and found a resistor, plus what looks like a capacitor in series with the lights. Is this really a capacitor? If so,...
- 255
0
votes
0
answers
28
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LED circiuit for a current limited circuit
I have the following requirements for a circuit:
The circuit is supplied from a 500mA current limited voltage source
The circuit should indicate the status of the supply, i.e. if it is in current ...
- 125
0
votes
1
answer
337
views
Limiting the Current of a Constant Current LED Driver which is Driving a Halogen Bulb
I am powering a 12V, 35W halogen bulb with a MeanWell HLG-100H-20B constant current power supply. The "B" version of this power supply has a really neat dimming control system which lets one control ...
-2
votes
1
answer
107
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Do I have to use current limiting resistor for LED in this configuration?
LM741 datasheet says that it can output a maximum of 20-25 mA. So in this case, is that R5 a must, or will it be safe not using it?
Assuming LEDs can withstand 25mA.
- 2,106
0
votes
2
answers
59
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Reducing current in a circuit without reducing voltage [duplicate]
I didn't find a solution in the other similar posts or maybe I don't understand them.
Here is my problem : I've got power supply with an output of 5V and 8A to feed 128 leds drawing 5V and 50mA each. ...
3
votes
1
answer
768
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Why are these LED current limiting resistors so big?
I'm looking at the charging circuit for a lithium ion battery that was made by Adafruit. Here's an excerpt:
If there's a 5V rail from the USB port and a 470 Ohms resistor, is that limiting the ...
- 626
1
vote
2
answers
257
views
High power LED array
I’m designing SLA 3D printer and I need to design UV LED array for LCD screen backlight. Preliminary design is 5x3 (5 parallel lines with three LEDs in each). All LEDs will be soldered on PCB.
The ...
- 53
1
vote
1
answer
1k
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4 channel optocoupler [duplicate]
I was designing a dual H bridge board which uses some logic signals to drive 8 mosfets. Initially I was using 8 optocouplers per board which was really annoying to wire up. after a bit of searching, I ...
- 347
0
votes
1
answer
117
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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
1
vote
4
answers
1k
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Why my hex inverter chips (all three of them) are not producing a HIGH output with low input?
I wont say I am great at reading datasheets, but I noticed that for 74LS06 chip, Ioh is 0.25 mA and Iol is 40mA. Does that mean it can light-up an LED when its output is low but not when its output is ...
- 120
0
votes
3
answers
849
views
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 ...
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1
vote
2
answers
1k
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Overcurrent Protection for COB Leds wired in parallel powered by Const Voltage Mean Well Driver
Roughly this is my current wiring diagram.
The Mean Well driver that I am using is the HLG-185H-36B. Output 36v DC, max current 5.2A. The Cobs are 36V and have a max operating current of 2.76A, ...
- 11
1
vote
3
answers
2k
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Switching circuit for driving LED at different current values
simulate this circuit – Schematic created using CircuitLab
Above schematic is for limiting current to 4A when battery is connected to LEDs.
Datasheet of LED(BXRA-56C5300H 50W) are 23.5 Vf and 2....
- 9
3
votes
3
answers
2k
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Current limiting from a USB supply
I am designing a device which must power a number of RGB LEDs. I am currently looking at WS2812 "NeoPixel" style LEDs, which have a max current draw of 60mA each. I would like to have a large number ...
- 133
0
votes
4
answers
3k
views
SMD LED for microprocessor output without resistor [closed]
I have a very simple problem to solve and I'm surprised there is no common solution for it.
I need to connect several indicator LEDs to microprocessor outputs and I know I need a serial current-...
- 117
0
votes
2
answers
193
views
Effects of current/voltage limiting of LEDs
First of all, I have read many articles about the non-linear effects of voltage vs current of LEDs. I also know that current will rise as temperature rises, batteries have resistance, LEDs brightness ...
- 43
1
vote
2
answers
1k
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LED indicators for HVAC (24 VAC)
I have an HVAC which I would like to add some status indicators to. I have some tri color LEDs, but could use suggestions as to how to utilize those LEDs.
What I am figuring is that I need a diode ...
- 149
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 ...
7
votes
2
answers
701
views
Current limiting resistors
I notice that in Ben Eater's project for the 74 series logic chip computer, which my son and I are building, sometimes he uses current limiting resistors on LEDs on the pins of some chips, and on ...
- 193
5
votes
5
answers
878
views
Dynamically dimming individual LEDs in a lighting system [duplicate]
I'm planning to build an aquarium lightning system with individually controllable LED's, I don't have much experience with electronics except from the irregular tinkering, but I'm a programmer and I ...
- 158
0
votes
1
answer
121
views
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" ...
- 3
0
votes
1
answer
1k
views
Calculating LED current using ohms law
I've got a 4 digit green 7 segment display (technically 5, it's from a microwave and the "5th" digit is the function lights on the top and bottom). I don't have a datasheet for it. It's common cathode,...
- 347
0
votes
1
answer
301
views
Common current limit resistor for multiple LEDs?
First, I realize the "common resistor for multiple LEDs" question has been asked. However, I have a different case where the LEDS are FET driven and reverse logic.
I have the following circuit. The ...
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0
votes
4
answers
3k
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How to get a constant current from a DC power supply for high voltage/current
For a project we're working on we require 4 high power LEDs, we've been using these: http://www.digikey.ca/product-detail/en/bridgelux/BXRC-50C10K0-L-24/976-1277-ND/5180249.
We've purchased this ...
- 1
1
vote
4
answers
835
views
Large parallel strings of LEDs
I want to drive multiple strings of XTE LEDs (total of ~36 LEDs). The relevent (-ish) specs are as follows:
I_f,max = 1.5 A
Desired I_f = 0.5 A
V_f = 2.94 V (0.5A @ 85C)
According to some ...
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
...
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4
votes
5
answers
10k
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How to limit current to LEDs
I have understood that this is a bad way to do it:
Since some LED can draw more current than others.
So lets say I would power some high powered LEDs, like say 10 x 3W LED with a DC forward voltage ...
- 697
0
votes
1
answer
453
views
Cascading WS2803 LED drivers, each with different output current
I've decided on using WS2803 PWM constant current LED drivers. I'd like to cascade two of them and use the first one for 15mA output and the second one for 20mA output (each chip for driving different ...
0
votes
1
answer
127
views
Voltages to keep my circuit running at 200mA with NMOSFETS
Im trying to build a circuit to send information using IR led, using pulse signals
my leds (TSAL6400) operates at 1.35V, and their maximum pulse current is rated 200mA
After struggling a bit with ...
- 227
0
votes
4
answers
2k
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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