36 votes

Is DC 5V and 2A dangerous to me?

200mA is lethal (actually much much less is lethal) and can kill, but only it if gets inside you. For it to get into you, it needs enough voltage behind it to push into you. If there is enough voltage ...
user avatar
  • 47.1k
26 votes

Calculate battery life

I would like to know how to calculate battery life when using LED strip. The LED strip is powered by 8 AA batteries. LED Current Draw = 260 mA. Right. The batteries will be discharged at 260 mA. This ...
user avatar
  • 160k
25 votes

How do filament LED bulbs work, looking very similar to incandescent bulbs?

These LEDs are not a single radial die, they are made with a transparent substrate with many LED dies in series (probably 25) placed on it. The whole thing is then coated in phosphor. The light isn't ...
user avatar
16 votes
Accepted

Why does a resistor in my Neopixel data line work at all?

The resistor is there to limit the current into the input pin. The input likely has a very high DC resistance (more than 1 megohm) so negligible current flows (on the order uA) and a negligible ...
user avatar
14 votes
Accepted

Powering 20 m LED strips

You don't need two power supplies. One is enough. Just connect the positive wire to one side of the strip and the negative to the other. Then you will have equal voltage at each LED group and this ...
user avatar
13 votes

Is DC 5V and 2A dangerous to me?

To make it easy: 1- Car battery 12V (hundreds of Amps) will not kill you. Laptop charger 20V 7A will not kill you. Therefore, the 5V 2A will not kill you also. Most of power sources you will see ...
user avatar
12 votes

How do filament LED bulbs work, looking very similar to incandescent bulbs?

I purchased one of these lamps in Italy: 3W/300lumens/9,00euros I took some pictures with very low exposition to higlights multiple "dot leds": I can count 28 dot-leds per each strip and 4 strips. ...
12 votes

Is DC 5V and 2A dangerous to me?

The power source you are looking into is a voltage source (like 99% of the power sources you interact with in your daily life). This means that 2A is the maximum it is designed to supply, but it will ...
user avatar
  • 257
11 votes
Accepted

5V vs 12V addressable LED efficiency

This is more interesting than it first appears. WS2815 appears to have been made in more than one revision but the latest design uses a clever constant current series trick. The lower half is a ...
user avatar
10 votes

What voltage is a 3-LED light from a LED-TV?

The 94V marking you see on the PCB is not a supply voltage rating. 94V-0 is a UL marking indicating the flammability rating of the PCB material. As others have said, you ideally need a constant-...
user avatar
  • 13.3k
10 votes
Accepted

Why would I need a capacitor in front of a LED strip?

The wire between your power supply isn't just a wire – it has a resistance and an inductivity. People tend to use thin wires, much too thin, and then wonder why their stuff fails in mysterious ways. ...
user avatar
  • 13.1k
10 votes
Accepted

What is the RGB value of Edison Light Bulbs?

I used Firefox Web Developer Eyedropper to grab the RGB from a photo of an Edison Light Bulb. #FACA08 (250,202,8) A lighter pixel This is very close to the color when a 2700K 97 CRI LED was ...
user avatar
9 votes
Accepted

MOSFET choice for 12v LED Strip and 3.3v Logic

The FET you link to is not suitable for your application. Taking a look at the "typical characteristics" table, we see this: Vgs(th) is listed as between 2 and 4 volts - already it could be higher ...
user avatar
  • 7,639
9 votes
Accepted

3.3v regulator problem when sharing power source with LED strip

The IRU1015-33 has absolute maximum input voltage of 7 V. You are operating the IC way outside its design parameters. Anything can happen, and 12V on your communication module is a real possibility. ...
user avatar
  • 37.4k
9 votes

DIY LED lamp is less powerful than expected

Your connecting wires are too thin, you are dropping voltage in your leads. You need to select the right size of wire and potentially use a star connection to drive the strings. If your strip is ...
user avatar
9 votes
Accepted

Edge-lit LED panel best materials?

What are the best materials to use for this? These panels are built in the same way as LCD monitors with LED backlight. Well, monitors have a LCD in front of the backlight panel, but you get the idea....
user avatar
  • 59.3k
9 votes
Accepted

Building a simple USB notification light

The cable is just that... a cable. The ring light doesn't have a USB interface. The Arduino's role was to interface between USB and the light. You need to keep either some Arduino, or another ...
user avatar
8 votes

How Many LEDs can be driven with one WS2811

The datasheet for the WS2811 is where you need to look. It is a constant-current three-channel driver that operates on 4.5 ~ 5.5 V, with absolute maximum ratings of 6 ~ 7 V. The output voltage is ...
user avatar
  • 27.5k
8 votes

Very hot mosfet when powering an led strip

Red LEDs have a much lower voltage drop than other colors so in order to compensate, the mosfet is having to drop a significantly higher amount of voltage/power. Red LEDs usually have a drop of 1.8 V ...
user avatar
  • 12.4k
8 votes

Simplest uni-directional level shifter (3.3V -> 5V)

Maybe not lowest component count, but chances are that you have all parts readily available. Any general purpose low power transistor will do and resistor values aren't too critical either. Possible ...
user avatar
  • 32.5k
8 votes

Matching number of LEDs to power supply

According to the datasheet, the LED's Vf is 3.05V @ 1500mA, which is close enough to the 1400mA constant current provided by your power supply. The power supply's maximum output voltage is 69V. 69V / ...
user avatar
  • 3,634
7 votes

Serial chaining of LED strips

Be careful about what you mean by "in series". If you mean that you're connecting the two inputs of one strip to the two outputs of another, you're really connecting them in parallel electrically, and ...
user avatar
  • 165k
7 votes
Accepted

How do I get the PIR sensor to output more than 3.3v?

The PIR sensor output is a signal. It is not intended to drive LEDs directly. Fortunately we have such things as transistors that can switch LEDs on and off in response to a signal like what the PIR ...
user avatar
7 votes

Will a LED strip be less bright when I drive my mosfets with 3.3V instead of 5V?

They probably will, in my opinion, but there is no guaranteed with such a MOSFET. The key number is the guarantee of Rds(on) at the lowest gate voltage shown in the "Specifications" section. Vgs(th) ...
user avatar
7 votes

Using L7805CV instead of TIP120?

I have a L7805CV transistor No, you don't have one of those, as there is no such thing. You have a 7805 voltage regulator (which is not a transistor). and its looks same to TIP120 That is just ...
user avatar
  • 16.7k
7 votes

Calculating base resistor value

First you have to determine what the maximum collector current is that the transistor needs to support when on. Divide this collector current by the gain of the transistor to get the minimum required ...
user avatar
7 votes

Why is 12V the standard for LED strips?

12V might be the "quasi" standard because of the 12V car batteries/electrics that were there years before the LED strips. Of course no one is driving a single 3V led with 12V and a resistor directly....
user avatar
  • 6,046
7 votes

Is DC 5V and 2A dangerous to me?

Short answer No, Long answer, The confusion here comes from a few common misconceptions/misunderstandings. First being, "Current kills, not voltage" or similar. Yes, it is the amount of current ...
user avatar
  • 171
7 votes
Accepted

How to combat voltage drop on a 5v addressable led strip

how do I inject voltage into the strip without making the design look like overhead power lines? Run secondary 5V and GND wires that you connect to the far end of the strip. You can route them ...
user avatar
  • 7,102

Only top scored, non community-wiki answers of a minimum length are eligible