New answers tagged led
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Split WS2812B controlling each branch as if one contiguous strip
Get a microcontroller with three outputs and write a function in software that maps pixels 0-29 to output 0, 30-59 to output 1 and 60-89 to output 2.
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Is this LED circuit balanced?
Will the board currents and voltages remain balanced if the series strings are different lengths?
The only thing that affects the distribution of current in an LED light is the sum of the LED forward ...
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Do LEDs turn on because of heat?
Yes it is possible but unlikely from thermal generation.
Much more likely cause is having mains leakage current via soldering iron, or the iron just closing a circuit for current to flow.
The circuit ...
- 138k
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Do LEDs turn on because of heat?
I think it is because of thermal generation.
It can be because of the ungrounded tip.
Some soldering irons have grounded tips, some don't. Here's a possible scenario:
simulate this circuit – ...
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Are all ESP32 GPIO available for use?
A blanket statement of "No", because some pins are reserved for bootstraps, i.e. configuring from where the MCU boots and how. These may need to be pulled up or down during the MCU reset so ...
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Production quality issue?
My reaction would be contingent on the type of failure encountered.
As you mentioned, these failure rates might be acceptable in hobby projects, but they are certainly not suitable for professional ...
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Non-inverting driver for LED
You can directly drive a 2N7000 gate from a 5V MCU pin at a reasonable PWM frequency such as a few kHz. So GPIO pin high = 'on'.
Worst case MOSFET Rds(on) with 4.5V drive is 5.3Ω @25°C. Probably 50% ...
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Non-contact powering of LED indicator from a high voltage cable
You don't provide details of voltage or frequency, but given that you say "high-voltage" let's assume we're talking in the 11 kV range at 50 Hz or 60 Hz.
You also don't say if the plugs are ...
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How do you turn on an LED when the input voltage is less than 12V?
This design will switch on one or more LEDs with a reasonably constant current of 10mA, as soon as the supply voltage exceeds the LEDs' combined forward voltage. That would be 1.6V for a single red ...
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LED grow light series regulation?
The determining factor for your design is LED forward voltage (Vf) spread.
If all have identical Vf and you drive your series-parallel string with constant current, you will have equal current in each ...
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2023 LED grow light voltage challenge?
So, from my novice calculations, each elemental circuit is about 48V total. Is this right?
Your voltage calculations seem to be correct, except LED's product page suggests the white LEDs have a ...
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LED grow light series regulation?
See previous post What circuit for LED grow light? for more info and details. Essentially, it was about which circuit to use for a grow light with diverse diodes and whether each series string needs ...
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LED grow light series regulation?
I have a large panel of white LEDs that is constructed in a manner similar to your diagram. It has a small current sensing resistor in each string, but only one of those has a connection brought out ...
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Why does adding this capacitor cause other segments to come on when they should not?
10 uF is a HUGE load for a microcontroller GPIO pin. Is that really your capacitor value?
Here is the schematic for the 8401AS-1F from the XLITX datatsheet.
I have isolated the an area of interest, ...
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Why does adding this capacitor cause other segments to come on when they should not?
The problem is not charge flowing from C8 to the other segments, but charge flowing from other segments to C8, namely its cathode. C8 does exactly what you designed it to do: it stops the CC4 signal ...
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Why does adding this capacitor cause other segments to come on when they should not?
What is probably happening is that the capacitor is allowing leakage on the cathode of digit 4 so the segments that are supposed to be on for the other digits are showing up on 4 as well.
You don’t ...
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How do I run four 1 watt 3.4 volt LEDs with a 5 volt 2 ampere power supply without overheating?
Put all 4 LED's in series and use a high voltage Joule Thief circuit, like this one:
.
The key part of this puzzle is that you don't have to run them at one Watt each.
The resistor R2 takes the place ...
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How do you turn on an LED when the input voltage is less than 12V?
Riffing on Dave's answer, here's the low component way to turn an LED off when the sense voltage exceeds some threshold. Not for battery operation due to the continuous power drain, but 'fuse box' did ...
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How do you turn on an LED when the input voltage is less than 12V?
How precise does it need to be? The LM431 is a handy chip that includes both a voltage reference and a comparator. A couple of transistors can be used to switch the LED on:
simulate this circuit &...
- 171k
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12v LED lights powered by 2 different circuits
EDIT: Here is a much better solution I worked out with help from a guy on an automotive forum.
Basically we switched everything to the low side, wired the LED controller positive directly to the ...
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Drawer light circuit burns out
The IR proximity sensor isn't designed to drive a Darlington transistor directly. You can try a 330 ohm resistor from the base to +3.3V to get more base current.
Assuming that the online schematic is ...
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Drawer light circuit burns out
Yes, well there could be many things wrong.
That's no way to connect an SFH900 to a transistor or a power supply. But what you drew as SFH900 is not even an SFH900 but some sort of module.
So there is ...
- 138k
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Is it possible to modify 8-pin Christmas tree LED controller's functions?
Realistically, your only option is:
Reverse engineer the whole board.
Work out what microcontroller they have used from the pinout. There may be several common ones that would be compatible.
Buy a ...
- 19k
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MAX7221 with multiple LEDs per point
You can't put 3 in series, the voltage drop will be too high. If you put 3 in parallel, even if you solve the voltage matching issue, you will only get 1/3 the current in each.
The left circuit is how ...
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Philips 9 W luminaire quotes 7 A for 300 ms inrush!
All contacts in installation of LED drivers without transducer will be damaged. There are inrush current limiters to fit after the RCD-MCB device where these drivers has been installed. Inrush current ...
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How do I produce more even output with a 6V Joule Thief?
Feedback can be used to stabilize the output, making a power supply proper rather than directly driving the LEDs with AC as in the classic JT circuit:
Source: my site, Blocking_Oscillator_Supply.png |...
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What circuit for LED grow light?
"Is the draw from each string of LEDs so similar that there really is no need to regulate?"
Generally, yes. 18 LEDs is a large enough number that you can pretty much count on the Law of ...
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What circuit for LED grow light?
Generally, driving a diode with a constant voltage is a Bad Idea™. The current in any diode, including an LED, is an exponential function of voltage across it; for every extra 26mV (at room ...
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Using two supply rails (on supply and output pins) with 74HC595
That's not a good way of doing it.
This is even said in the data sheet; outputs should not be pulled above VCC, and 70mA total current should not be exceeded, and you are doing both.
If 5V supply ...
- 138k
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Using two supply rails (on supply and output pins) with 74HC595
Just a first note: You are not connecting 5V supply to the SR output pins, there are the resistors and LEDs in series. These limit the clamp current to \$I_{OK} = {(V_{Supply} - V_{f} - V_{OH}) \over ...
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How do I produce more even output with a 6V Joule Thief?
Pre-Summary
We will run an experimental simulation showing that replacing the 1K resistor of a Joule Thief with a constant current source will produce more even brightness over the life of the cells --...
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What circuit for LED grow light?
leds in parallel will be running at the same voltage, leds in series will be running at the same amperage. with multiple parallel rows of leds wired in series, you can combine different types of leds ...
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What circuit for LED grow light?
All in parallel would be a lot worse. From a constant voltage source (PWM or not) would be worse again.
Series diodes all have the same current flowing through them and differences will tend to ...
- 384k
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Pull-down resistor with LED on a logic input
The LED and resistor cannot reliably pull down the BUS7 input to the 74LS377 to a logic LOW.
The LS family have a high input leakage current out of a LOW input. The TI 74LS377 datasheet states that an ...
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Potentiometer rated power and 16 LEDs
I have found the Joule Thief circuit to dim nicely and be quite flexible. I have worked up something that might serve as a starting point for doing what you want, and also learning more. Note that ...
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Wiring a DPDT switch for two LEDs as current output indicator
Let's redraw the schematic first.
simulate this circuit – Schematic created using CircuitLab
The schematic should read from left to right, top to bottom. That means that power should flow from ...
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Wiring a DPDT switch for two LEDs as current output indicator
One simplified option would be to use a single Bipolar LED. The LED actually contains a Red and a Green LED in opposing polarity. With DC voltage across the LED only the Red (or Green) section would ...
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Drive Power LED with a BJT
In the first schematic, the transistor is used as a switch. When it's on, it will be saturated, ensuring lowest possible wasted voltage on Vce. The resistor in series with the LED sets the current, ...
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Problem with LED driver - LEDs do not switch on when button is pressed
The maximum recommended total output current is 20 mA. Per the datasheet, the minimum current setting resistor value is 24K. The driver might be shutting down due to overtemperature caused by ...
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Problem with LED driver - LEDs do not switch on when button is pressed
If you expect the 7474 to act as a divide-by-two you need to pull the set and reset pins high, not low. You should refer to the truth table in the data sheet.
You have other issues:
The simple switch ...
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How to make an LED light when motor stops running?
Swapping the inputs to the op amp (or comparator) ringed in red will achieve what you want.
OR
Change the LED driving transistor to a PNP, emitter to +5, collector to ground via LED (with appropriate ...
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TPS2553 Current limiting for RGB LEDs
FAULT is open drain, so it shouldn't matter which choice you make. Datasheet doesn't mention any alternative way to connect FAULT than a pullup (another way to implement the signal is described in 10....
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How to make an LED light when motor stops running?
This is not an actual answer, but I have to do it this way to provide a schematic, so bear with me.
Your output stage may give you difficulty, especially if you are trying for output near zero, which ...
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TPS2553 Current limiting for RGB LEDs
You can tie the ENABLE pin to USB+5. The only reason to connect it to a GPIO would be if you wanted to shut off power for some reason, which seems pointless if you have addressable LEDs that you can ...
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6 amperes in transformerless power supply
Due to the low dynamic resistance of LEDs, a capacitor in parallel with LEDs will not smooth the current that much unless its value is enormous. Here even with 2000µF, LED current variation (ie, ...
- 72.1k
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6 amperes in transformerless power supply
Even if we ignore the diode issue as per your comment 1n4007 is an example , will replace it later, the capacitance will be one of your biggest practical limitation....
- 30.4k
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6 amperes in transformerless power supply
C 100uF/400V
That's a large cap. It needs to be at least X2-rated for safety, which rules out electrolytics (even non-polarized ones).
I was unable to even find an X-rated capacitor that big. The ...
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