# Tag Info

32

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 to push a lethal level of current into you, and enough of that current is actually available to push then it is lethal. Think about a bullet. It's a little ...

13

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 are voltage source. Therefore, the current will follow the voltage (by other way the current is dependent on the voltage ) and the impedance (your impedance here) ...

11

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 try to keep a steady 5V. Thus, the current is determined by the electrical resistance between the terminals. It can't kill you because your body electrical ...

7

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 that determines how much damage is caused. However it is the voltage that determines how much current can flow. Ohms law states V=IR and therefore I=V/R. A human ...

6

Just to add two aspects not mentioned before: a 2A load can badly burn a (DC) cable and burn down your house, this could even kill you in your sleep, so always be careful. Also, bad (cheap) power supplies with missing ground connection or poor (transformer) isolation between primary and secondary stages are not unheared of. This can either cause fire or ...

5

AFAIK it doesn't have a fixed name, apart from 'the WS2812 protocol'. As described, it is a fixed-cell pulse-width encoding. FYI: in practice, it isn't fixed-cell at all: provided that the pauses (T1L, T0L) are shorter than Treset, all that matters is the pulse width (T0H, T1H). This makes it a plain pulse-wdith encoding, and it makes bit-banging waaaaay ...

4

I2C is bidirectional, you don't need bidirectional level shifters for the WS2812B which uses a single-wire asynchronous protocol. For example, 74LVCH1T45 is a suitable unidirectional level shifter that will work with a wide range of input and output voltages. Edit: Bidirectional level shifters with discrete MOSFETs that use 10K pullups will likely cause ...

3

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 constant current (say 16ma) regulator. The top rail is at 12v. If you want no leds, you turn off the regulator. If you want 0xFF0000 (red) you turn PWM3 off and ...

3

I think it's time you read the datasheet for the WorldSemi WS2812B. You have to supply them with 5.0 Volts. 12 Volts will likely kill them, although because there's so many of these in parallel across the bus on such a long & high-density string, you might've gotten lucky and had the 12V rail sag so much that they didn't see 12V for very long. At full ...

3

Put one WS2801 chip on each strip. This avoids the need to program a generic microcontroller, as well as some of the external components it needs. You'll still need external driver transistors for the LEDs (same as the micro), as well as the local power regulation that Olin is describing.

3

Put a microcontroller on each strip. That does the PWM locally for each color of that strip. You don't want to run PWM lines a long distance anyway. The signals will be messy at the ends of the wires, and they would emit a lot of RF interference. Use a micro with CAN built in. Connect all the strips to a single CAN bus, with a separate master that tells ...

3

The 74HC245 is not a level shifter. If you want to reliably shift up you should either use a proper level shifter with two Vcc connections and a DIR input (for example a 74LVC4245, or if you want to just convert up you can use a 74HCT245.

3

Your skin is the body's largest organ. It is a fairly good insulator but your internals (muscles, bones etc) is more like a fairly good conductor. The skin is able to withstand 5V (and even more up so 50 V is deemed as safe, I work with equipment there upto 48 V can be expected , and well everything have wiring posts which isn't insulated so it exists a fair ...

3

The WS2812 LEDs are turned on by instruction data shifted through each LED chip. This is explained well in the WS2812 datasheet. There is no simple "pull the data line high for a second and they'll all come on" technique. There is a reset command which is rather easy and that is to hold the data line low for 50 μs and all the LEDs will turn off. To do ...

2

You are right, it should not be using 8.64 amps or 43 watts with a single 22 AWG wire. Of course, that 144 led strip looks like it has two power and two ground cables of 22 awg, doubling the copper and essentially having the same capacity as 19 awg wire. So those wires themselves would be fine. You also have to factor in the high resistance of FPC. Even if ...

2

The WS2812B datasheet tells you: Each pixel is 3 * 16mA = 48mA max per pixel. A 15A 5V power supply is required at minimum to power your whole strip at maximum white. The VCC voltage per pixel is a nominal 5V (the controller in the chip generates a 12V CC to drive each LED). The pixel will work perfectly from 4-5V and so you can support a voltage drop over ...

2

Good way to smoke a load of LEDs! They draw current depending on the individual unit brightness settings, so this will not work (Among other reasons having to do with the need to level translate the data between each stage). Use a small switching regulator to take the 24V down to 5V and use that to power them in the normal way. Regards, Dan.

2

Light pipes with side emission are used a lot in automotive. My 2015 Camaro SS2 convertible comes with light pipes in the door. Search around the automotive add on markets. Source: camaro5.com This might do the trick. It will be a very close fit. This one is for 2 mm flexible light piping and RGB LEDs. The WS2812 is 5mm x 5mm This light pipe adapter ...

2

Aside from a light pipe, a hard plastic version of fiber optic cable that is used in most commercial products to redirect light from a surface mount led you can use a clear epoxy to mate the fiber optic cable to the 5050 package. You must make sure you use enough to create a structurally strong connection. This is why your other attempts fail, as hot glue ...

2

You will want to tie all grounds together, including the ground of the MCU. Remember that voltage is a potential between two points. If you have two different devices with a single common point, that will typically be "ground". That way, the potential to all other points will have the same reference (0V). Without a common ground, connections between two ...

2

Looking at the datasheets at https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/README.md, the PiZeroW has no fuse. (Compare for example with the Pi 2B, which has a fuse at the USB input) Now, a Ws2812b draws 60mA when set to full white brightness (255;255;255). This makes 1080mA, which is already more than what your 1A power supply ...

2

The code was correctly transmitting the DMA sequence, but the DMA needed to be changed to circular or repeating mode to see it on a scope. When it was just running in linear or one-shot mode, I didn't have a chance to see the output the single time it was produced.

2

A high-definition (1080p30) video stream represents about 1.5 Gb/s of data. Commercial video walls (a.k.a. "Jumbotron") are built up from edge-stackable modules (anywhere from 1000 to 10,000 LEDs per module) that are typically networked together using Ethernet. A master controller receives a video stream over any standard connection (HDMI, etc.), and then ...

2

10 A because 150 LEDS of 60 mA need 9 A. Correct. I pretty sure that my jumper wires will not like 9A. Correct. So why tutorials and guides (see links below) don't care about wires when using 10 A with 5 V to ligths up strip LEDs? You'd need to ask them. What kind of cables should I use to connect both the Arduino and the LEDs? First ...

2

According to the reference manual: OCx polarity is software programmable using the CCxP bit in the TIMx_CCER register. It can be programmed as active high or active low. So you need to look up the bit assignments of that register and set/clear the bit as appropriate, or look at the API for abstraction library you are using and ask it to do this, for ...

2

5V and 2A is not lethal itself. 5V and 2A also won't power a load that needs 5V 7.2A, so perhaps only less than 40 LEDs can be fully on at one given time.

2

Global variables use 1952 bytes (95%) of dynamic memory, leaving 96 bytes for local variables. Maximum is 2048 bytes. Low memory available, stability problems may occur. You have assigned 1952 bytes of RAM to global variables. Those are declared outside of function scopes, or inside function scopes with the static keyword. The remaining 96 bytes is all ...

2

Try adding decoupling capacitors. Decoupling capacitors are like sugar and your primary power supply is like fat. The first is fast and on-demand, the second is high energy but slow. If you try to do strenuous activity and your blood sugar is low, you pass out. Same thing with circuits, more or less. All connections have inductance so sudden changes in ...

1

Will WS2812B overheat because of epoxy? It may or may not overheat. That depends on the amount of power which it will be dissipating. That in turn depends on the amount of light which you will be generating. [The LED strip with WS2812B] will be glued onto wood and then covered with epoxy from the top so that all the components of the strip are in the ...

1

This is based on a few sources including the (poor) datasheet. My interpretation is that BIN should be connected to the previous LED's DIN. Then if the one LED fails, the next one will not receive any data on DIN, but it will receive data on BIN. It will switch to backup mode, where it uses the data from BIN, and ignores the data intended for the previous ...

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