# Tag Info

### Did my WS2812B strip come with wires way too small for what's needed?

The 60 mA per LED is the max rating, not a typical current draw. The strings that I have measure about 32 mA per LED. You should measure yours. PWM at a lower percentage and extrapolate. For a long ...
• 16k
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### Measuring the resistance of an LED -> getting conflicting values

I couldn't find the resistance values for an LED so I tried to measure it An LED isn't a resistor, and won't behave linearly the way you're expecting it to - your mental model is flawed and Ohm's Law ...
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### Measuring the resistance of an LED -> getting conflicting values

A red LED at reasonable current levels has a voltage drop of about 1.8V or 1.9V. So with a 3V supply and 100Ω series resistor we would expect a current of about (3-1.8)/100 = 12mA With 200Ω series ...
• 398k
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### Why the LED heats up and fails to pass the controlling information further?

I think there are many things not entirely correct. First of all, it is a miracle that you can use that logic level shifter at all. Most people here simply ask why it does not work level translating a ...
• 149k
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### LEDs forward voltage at minimum brightness

The problem with voltage-driving LEDs, which is what you are effectively doing, is that the LED forward voltage varies with temperature. This could explain your anomolous voltage readings, which ...
• 167k

### Did my WS2812B strip come with wires way too small for what's needed?

24AWG wire has a cross section of 0.2050 mm square. If we generously assume your LED strips have a 4 mm wide positive and 4 mm wide return trace using 1 oz copper, their cross sectional area is 0.140 ...
• 17k
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### How to make smooth LED brightness control without PWM?

Filtering the TI LED drivers parametric selection for single channel and current mode devices to look for possible devices which don't use PWM. On possible candidate is the LM36011 Inductorless LED ...
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### Unpowered LM393 Comparators

There is no need to add any circuitry. The inputs can withstand -0.3V to +36V regardless of whether supply voltage is applied or not, and even without current limiting. Many other comparators (such as ...
• 398k

### Using resistor network instead of regular resistors

It depends on the exact topology of your array, but it's generally possible. Supposing you have an IC configured as follows: simulate this circuit – Schematic created using CircuitLab Assuming ...
• 20k

### Non-inverting buffer to drive LED using different power source

What you appear to want is a same-polarity buffer that can drive an LED on a different rail, using the function: GPIO LOW for LED lit. You can use a single-gate 74LVC17 buffer IC, a cheap and readily-...
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### Using resistor network instead of regular resistors

Yes it is possible, and commonly done in commercial equipment. There are different types of resistor arrays, some have one pin of each resistor available, and the other end of the resistors are all ...
• 23.4k
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### Can single digit 7-segment displays use free digits from a multi-digit multiplexer?

Yes, you can drive the additional digits as they are both common-cathode. The AS1115 seems particularly well-suited since (according to the datasheet big print) it allows brightness to be set on a ...
• 398k

### Why the LED heats up and fails to pass the controlling information further?

I mentioned bypassing DIN to DOUT on the suspect LED as an initial test, though I think your problems are more fundamental than that. Recognize that RGB LEDs draw a fair amount of current. At first ...
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### LED light bulb is flickering when switched on

So the light turns off when the LDR is illuminated. Your first problem is you have to decuple the light generated by the lamp from the LDR - you set up what's known as a hysteric oscillator - light ...
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### How would I decide on the best LED intensity for TCS3200 sensor

Basics Cool project! You should know about potentiometers So, if you should really go with resistors, you'd honestly just buy an adjustable resistor, a so-called potentiometer (the ones meant for &...
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### Control a large array of high-power LEDs with a GPIO pin

The chosen MOSFET is more than enough to accomplish the task, although it would be nice to know the driver voltage. There is no need for a "beefier" device. The bench testing failure is due ...
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### Measuring the resistance of an LED -> getting conflicting values

A LED is not a resistor so it won't register with a multimeter to a resistance value. As a first order model, an LED has only a forward voltage (Vf) drop. If you look at the I-V characteristics of a ...
• 14.8k
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### Why I am getting wrong mA on Tinkercad?

The voltage over resistor is not 5V, so no the current should not be 45mA. According to your simulator there is 2.871V drop over resistor. The remaining 2.129V are dropped over the LED. And no, LEDs ...
• 149k
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### Dimming for high power led

You can't dim a constant-current LED driver in this way as the driver will simply increase its output voltage when the MOSFET disconnects the LED, thereby sending the FET into avalanche breakdown, ...
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### Did my WS2812B strip come with wires way too small for what's needed?

Minimum current consumption with one color on is approximately 1mA. Not only connected wires but PCB conductors cannot carry big current. Also drop voltage on PCB conductors could be taken in account. ...
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### How to make smooth LED brightness control without PWM?

You may be thinking of low duty cycle PWM which can look bad, especially at low frequencies. Current-control LED drivers that switch into an inductor and have a sense element in the loop will not have ...
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### Purpose of electronic elements in a capacitive dropper circuit

The circuit you provided is borrowed from this answer I gave to a question you posed earlier. I borrowed it from a blog post I wrote a couple of years ago about cheap LED bulbs. In that answer, I ...
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### Using resistor network instead of regular resistors

You can do this if you use networks that are appropriately rated (watch the power rating and allow adequate safety margin for your environment extremes and reliability requirements). It's a very ...
• 398k

### Non-inverting buffer to drive LED using different power source

the LED is expected to light when the signal is low. Well - - - that changes everything. Still, this is possible with only one transistor because the LED Vf is greater than 5 V minus the sum of Voff (...
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### Non-inverting buffer to drive LED using different power source

ADDED: THIS IS A GOOD ANSWER TO THE ORIGINAL QUESTION. It assumes that the LED is lit when the GPIO drive pin is high - as originally implied. - RM If the GPIO output is 3.3 V and the LED Vf is 2 V, ...
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### Non-inverting buffer to drive LED using different power source

ADDED: THIS IS A GOOD ANSWER TO THE ORIGINAL QUESTION. It assumes that the LED is lit when the GPIO drive pin is high - as originally implied. - RM while GPIO is 3.3V, I want to drive the LED using ...
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### LEDs forward voltage at minimum brightness

As Neil_UK said in his comment, you can keep the two LEDs in series with no resistor (or a zero ohm jumper instead of a resistor) or 10 ohms, it won't make much difference. 5V is already less than the ...
• 2,330

### LEDs forward voltage at minimum brightness

You have an MCU -- use your microcontroller as a voltage doubler or tripler. Since you only want to ensure the dimmest illumination, not brightness, this is perfect. Dave Jones of EEVblog fame has an ...
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### Modulation Bandwidth of LED

The issue is probably how you're driving the LED. They're nonlinear circuit elements, so if you try to drive them as you would a resistor by modulating voltage they don't respond linearly. Instead, ...
• 17k