4r7 smd resistor

[Ray] It's a bit salty. When he started selling products based on ESP8266, everything seemed to be fine, but shortly thereafter

. Don't worry, he recommends ignoring the problem, because once the faulty component evaporates, the device is fine.

The symptom is that the car's red power indicator light smokes. (Possibly) The LED is okay, because when testing the batch, he found that its current limiting resistance is sometimes a little lower than the specification. Almost, it can even be said to be 1,000 times.

Yes, sometimes the 4700 ohm resistor is replaced with 4.7 ohm. Go through the power rail. That poor little LED tried to dissipate half a watt on the needle. Like a sparrow trying to slow down a sledgehammer, its ending is not good. Try not to be too picky, sometimes it is difficult to choose n to put the machine, everyone knows that these reels look almost the same!

The good news is that LEDs and resistors have started a hot race, and whoever wins will escape in the breeze. After the connection is disconnected, the heat problem quickly disappears and the power consumption returns to normal. Unless you need the indicator light, everything is fine. Behold-a lot of repairs can be done with zero tools, zero effort and just a few seconds.

If you are one of the few unfortunate people, [Ray] also recommends measuring and desoldering resistors or LEDs, or, if the worst, he is of course willing to replace the product. He did his best to purchase goods from real suppliers and apologized to the few customers affected. As far as he knows, no one else has encountered this problem, so he wants to share it with the community here as soon as possible on Hackaday. caution.

If you have never seen

Before, there was a short video

I was caught by the tape after the break.

Is there no test before shipment?

You get what you pay.

This is true, although in terms of price, I don't think they will carry out quality control. Manufacturing and selling them is an urgent matter. There are many changes now.

I can buy 5 for 15 dollars.

At least this is shared. Other users can at least test their situation. Maybe posting on the forum?

You will get a great product. And, most importantly, you pay 1/2 the price for someone who needs to "test".

exactly. In addition, I asked the eBay seller to refund and refunded 100%.

So: I paid any price for what I could still do.

Can I really complain? -almost not.

The manufacturer may have tested these modules, but because smoking only occurs after about 10 seconds, they will not notice it easily if the test process is less than 10 seconds.

For such a module, the test should include wifi performance (it may take more than 10 seconds) and power consumption. Not to mention the calibration steps, it may not happen either.

They should recognize the increase in power consumption.

Well, current/power consumption may not be part of their testing procedures; otherwise they may use lower voltages (such as 2.2V or lower) instead of 3.3V for testing, in which case no symptoms will appear. It's not that I know what happened, just think about all the possible reasons why it fell into the crack.

I guess they are not tested at all, as already mentioned (die PCB, not die), you get what you pay.

Lol, test with 2.2v? Why would you do that? How to test without testing? Doesn't the test mean running at the required voltage?

But in any case, I think the test of this type of product may be performed once every 100 times, and then only once for a short time.

@Whatnot: What does "required voltage" mean? The operating voltage of the module is 1.7V to 3.6V. Although 3.3V is the standard voltage, there is no specific voltage that is required.

@Ray I’m bad, thank you for pointing out my mistake, even though the module requires 3.7.

"The operating voltage of the module is 1.7V to 3.6V"

Indeed, such a reasonable test should be to run the module at 1.7V and 3.6V. I don't want to test the absolute maximum and absolute minimum for each module, but if you want to do this, of course you should test under the two extreme operating limits.

No, at this price, there is no quality control at all. In addition, the crystal may be 50 ppm higher than the required 10 ppm, and the SPI flash memory chip may have been refurbished or defective...

But what you get is what you paid for!

Zero facts and many speculations.

Interesting, but this means that the module has not been tested before leaving the factory, so no calibration has been performed. I think you will get what you paid.

After putting the PCB antenna into the housing, unit calibration must be done, because even the plastic housing will greatly change the performance of the antenna. Despite this, ESP8266 provides me with very good wifi performance. Maybe like some mobile phones, it has some automatic antenna tuning features.

Counterfeit smoke? Now I have heard everything.

It is not necessarily counterfeit, but it shows that the circuit board has not undergone any functional testing, which will cost more. This can be detected even by testing random samples in a batch.

I saw Digi-key mislabeled parts. After a long day, if a person is loaded into the reel, it is only a problem to read 4R7 as 4K7.

This can also happen with real products. Whenever possible, our North American CM will conduct flying probe tests on part values. For R&C parts whose values ​​are too high or too low to be measured in the circuit, we are told that they must be used with test pads. All of this and the complete set of continuity/functional testing to find errors/production problems, because our products are too expensive to be discarded.

If it is from China, it is "all rubbish, no quality control"; if it is from North America, it is "messed things, reduce their slack."

If you are from China, you will get the required fees. Just like all high-quality products using Chinese parts and manufacturing.

almost not. Smoke is as real as smoke. No imitation smoke is produced at all. The actual ingredients are evaporated. A +++ will burn again!

kes! That is bad manufacturing.

Do you object to the Republic of China?

Oops, I mean China. I apologize to the Taiwanese. Dear Harder, I would love to edit the button...

Yes, I will, but I will not pay for it. China does not mean cheap. China means paying a price. If the cost is low, you will get what you need to pay. If you need some high-quality telescope optics, or a PCB with 12-layer PCB and 2mil trace tolerance from China, then you can still get what you need.

When I found that assemblers used 4k7 and 270k resistors interchangeably (yellow-purple and red-purple-yellow), it reminded me of a problem in the workshop. We solved this problem by changing a value (I think 220k or red-red-yellow).

Color dyslexia? I think I occasionally encountered...

This is not the so-called smoke test...

(

)

"When things get worse"

Such as: "When some bad conditions become completely bad"

You mean "when something gets the worst, it gets the worst".

I disagree :)

"

The expression should be:

If the worst happens,...

This means "if the worst possible thing does happen...".

In my opinion, if it is contracted without clear terms, it does not seem to prove that "the worse situation becomes the worst." It should still be "the worst case becomes the worst".

"

Let me put on my parachute pants, none of you can touch them, this is grammar time!

According to Oxford University, "worst to worst" is the word's popular bastard in the United States.

Both idioms exist, and their meanings are slightly different.

Spoiler alert-I am an ancient dragon living in Canada.

<- Obviously, "worst case" is a traditional English idiom. "The worst is the Americans." Maybe we can blame the metric system.

<- For centuries, this idiom has been "from worst to worst", although if it makes you feel better, because at the turn of the millennium, the absurd "from worst to worse" will also take over.

Why are we talking about this?

Well, the New York Times wrote the whole article.

<– "Idioms are like barnacles on a language boat."

Worse:

"The idea contained in the original idiom is the idea of ​​the worst that happened. "Come on" here means "result" (such as doing nothing), so the phrase describes the worst thing in theory becoming the worst thing in practice. Bad things."

Worse:

""If the situation gets worse, I can only die. "A subtle change in a letter changes the interpretation of the phrase, not only marking the deterioration from deterioration to deterioration, but also from relatively deterioration to the worst deterioration, marking a downward development process., especially because of the worst last" t "It can be swallowed by the sound of "k" at the beginning of a daily speech."

Therefore, "Worse" looks like a sneaky attempt to take the free train to the big city.

It doesn't matter, he succeeded, and now we persevere:

"In standard English, both the worst/worst and worst/worst variants are acceptable. If the worse/worst seems more logical to you, you must take this opportunity Make idiomatic language more reasonable."

I want to quickly state "when the worst becomes worse", such as "when the worst becomes unimaginably worse." I think it is underrepresented everywhere, but this is my favorite variant.

My favorite is "When the little sausage comes"

Am I right, these transactions can run 200 microamps?

I = (Vcc-Vfd)/R

0.000255 Ampere = (3.3 Volt-2.1 Volt) / 4700 Ohm

No, I think the value should be 470 ohms. 4.7k is too big.

Yes, that's right. Approximately 0.2 mA. So the LED is very dim. Since this is just to indicate power, it is best to set it to consume as little current as possible. To be honest, I think this LED is not very useful, especially when working on low-power projects.

Agree, if needed, flashing every few seconds, but it must be done within a short period of time, but turning it on permanently will waste energy.

I don't know if you will see a lot of 3v3 power supplies, 1.8V LED forward voltage and 200uA (4K7 resistance) light-it seems unlikely, but I need to experience it to find out.

I am pretty sure it is 4.7K. I measured at least ten modules, which is consistent.

Agree that 4.7k is a good choice for them. This is not annoying, but it will tell you whether there is power. Coupled with the blue LED indicator, it can let you know that it is working and will not keep you awake at night.

I checked 2 of mine: 4.7K for red LED and 2.2K for blue.

Yes, I just tested my game and got 4.7K, so I panicked.

Thanks Ray for the warning.

Actually something is wrong. I just measured it: at 3.3V VCC, the LED drops about 1.8V, while the resistance bears 1.5V. So the current is actually 1.5V / 4.7K = 0.32mA

From a perspective, have you ever run a normal T1-3/4 through-hole LED at one or two mA? It is easy to see light even at such low power, right? Now consider how much smaller the size of the SMD LED is. The thing you are illuminating is almost a grain of salt, and the power required to obtain the same brightness in a smaller area is correspondingly smaller. When considered in this way, 200uA makes much more sense.

Interestingly, when you use USB3.0, the speed will be twice as fast:)

You see more power and faster destruction.

Oh, and a side note: I heard that the first batch of USB3.1 motherboards are already on the market, so the chip is ready, and soon we will have USB3.1 devices, which are twice as fast as USB3.0 and with There are plugs that can be inserted up or down on either side.

And the power is over 3.0. So get ready for tinker

3.0, we hardly know!

Please wait, the current that the USB port can output is different from the actual current consumed by the circuit. Just because USB 3.0 can output twice the current does not mean that the circuit will be disconnected faster.

But something is broken, because the resistance is wrong, and the resistance is burned out, it will definitely double the current, which will speed up the resistance. Basically, the only resistance is to limit the power supply under this misconfiguration.

V = IR? With USB, the voltage is still regulated: the current will not magically rise without first having any effect on the resistance.

Constant resistance

When they burned.

Maybe I read it wrong, but I'm not sure what you are talking about? The USB standard requires the host to limit the current, which is actually the limiting factor in the case of incorrect resistor configuration.

The USB device may initially absorb a unit load, 100 mA in the USB 2.0 specification, and 150 mA in the USB 3.0 specification. Since this device may no longer require more power, the nominal power consumption of the resistance of the LED for USB 2.0 is ~0.5 W, and if USB 3.0 is used, it is 0.75 W.

Assuming that the USB source is smart, it is almost certainly not.

The whole USB specification is an electronic honor system. The device should request power and can only be used after approval. But power rails are usually just power rails, you can draw anything you want.

In this case, the LED crosses the Gnd of VCC and ESPy, and the latter knows (out of specification) that the chip itself decides how to use USB to supply power.

Okay, of course I understand what you mean, but if we just say "Ah, but not everyone follows the specification", then there is no point in talking about USB 3.0 and USB 2.0. :)

If everything is powered by one of them, then the sky is the limit:

Yes, the formula applies until the circuit (LED and resistor) starts to burn, at which point the circuit no longer follows the rules stated on the resistor, which is the whole cause of smoke.

It boils down to one more time: you should study the law of calculating power to determine the amount of heat dissipation of the circuit in this case, and its heat dissipation capacity in this case,

For the USB specification, this is a reality. At least half of the USB connectors in the world have no intelligence at all. And even if the current intensity of USB3.0 increases by only 50%, if the specifications of these components exceed the range that they can burn, it can still burn them faster.

First of all, please read the actual USB specifications and don't speculate. RPi designers made this mistake.

USB voltage is highly unstable, and the voltage drop at each point depends on the wiring, connectors, PCB, PTC/protection circuit, diode (optional?) and internal resistance of the load (peripheral device).

>The voltage provided by the low-power hub port is 4.45-5.25V.

ESP8266 product? Is this the entire FCC joke? Can we really make things and put down these little boards?

ESPToy is a component, not an independent product. If you want to develop consumer products, please consider the version approved by the FCC, such as ESP-12.

I think this is just a kit because when you fully assemble it, it is a purposeful radiator.

Whether it is fully assembled or kit is not critical. This is a development board, not a device with a designated purpose. SparkFun has a tutorial on these topics:

. There is also a very informative article here:

.

Using FCC devices on your system does not mean that your system is FCC.

Yes, but using FCC approved parts will make your product more likely to pass the FCC on the first attempt.

For HaD, this can be an interesting challenge, using only FCC-approved modules to make devices that are as non-compliant as possible with FCC regulations.

That will be a challenge. It's time for me to refresh my EE! ! !

Oh, I like it!

Microwave to microwave transmitter...

Is this half a watt transmitted via esp8266 gpio?

The smoke from Alibaba has not been noticed, and it has been running for several months. lucky!

No, it is transmitted through VCC (the power indicator LED does not go through any GPIO). This is a very rare problem-I have purchased hundreds of them and this is the first time I have seen this problem. Just a bad batch.

Very good, then don't worry. So far, I'm really lucky with these things. I have used 80 of them. Only one pair has poor performance. I noticed solder spots on one pair of antennas.

Definitely the favorite device of 2014

Yes, the brakes on this car will fail, but on the bright side, the bumpers are great!

Do you mean that the steering wheel "should" turn in this way? ! ? ! ?

Since October, some of my projects using esp have worked well, since 24/7.

I can only say good things about...

"I don't always create devices that fail. But when I do, they continue to work."

These people knew they were going to be tested by Chuck Norris, so they failed first.

You can assume that the self-check will take less than a second, but they are crazy, especially in the entire batch, they didn't pick it up, which is crazy.

Interestingly, if you look at some videos of the quality control facilities of the tablet/phone manufacturer, one of the first tests is the current consumption of the device under test. They have a chart/checklist to characterize (sp?) the current and current slew rate for known faulty components under different operating conditions. They don't even have to open the box.

These are not smartphones/tablets, and I don’t even think they even want to test them: they just impose panels on the modules, hand weld the connectors, and ship them immediately.

I have some 0805 LEDs, and their brightness is too high to observe with 5V and 5K. Red drops 1V8, green drops 2V4, and blue drops 2V7. Therefore, since the mid-1990s, all of these LEDs have had a current of 1 mA.

Oops, the forum deleted part of my post...and one more time...

Oops, the forum deleted part of my post...again...((Less than and greater than symbols:(

I have some 0805 LEDs, and their brightness is too high to observe with 5V and 5K. Red drops 1V8, green drops 2V4, and blue drops 2V7. So all of these are less than 1mA.

Since the mid-90s, I have not used more than 1mA for the LED.

"I haven't used the refresh button since the mid-90s." ftfy

I think this might be the reason why ESP8266 will power down my CP2102 USB serial adapter when powered by 3.3v power supply. (Everything works fine on a separate 3.3v power supply)

But I don't remember that there is a red LED on the board.

Look at 8K? Resistor and no red LED and empty pad with good flow. Therefore, I suspect that they found something wrong and started to leave them... The blue LED has the 2K2 mentioned by others.

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