I wanted to get a couple genuine Lolin/Wemos D1 Minis to have the best chance of getting a decent voltage regulator. The schematic I have says the genuine ones have a ME6211 regulator, but I understand the clones have something less capable.
Anyway, I ordered two from the Lolin store on Aliexpress, and tracking says they cleared US customs on the 17th. But they haven't arrived, and a week later there are no subsequent tracking entires. That seems to be a bad sign.
So I wondered if anyone knows of another source of genuine Minis, or a clone with a good regulator.
Define "decent voltage regulator", and "less capable".
Manufacturers could use/change to whatever is available, even the branded ones.
The only limitation I see is thermal, because the regulator is tiny and there is no heatsink (on any of them).
Not a problem though with an average ESP8266 current draw of <= 80mA.
Or are you planning to power high current draw sensors off the 3.3volt pin (don't).
Leo..
As I said, the genuine Mini appears to have an ME6211, which is a 500 mA regulator with 100 mV dropout. What I read online is that the clones use a Torex XC6204, which is either a 300mA or 150mA regulator (you can't tell which from the markings) with 200mV dropout.
I'm just powering the Mini. Nothing else draws any current. But my understanding is that during transmit the ESP8266 draws several hundred milliamps:
Dropout voltage just affects how long the battery lasts - an 18650. The difference isn't a deal breaker, and in fact may not even be noticeable.
But on the question of the regulator and that Mini capacitance, I'm kinda going with the video Andreas Spiess did on powering the ESP8266. This is all new territory for me, but I'm leaning toward adding that honking big 1000µF electrolytic on the 3.3V pin. And based on his kind words about the regulator on the genuine Mini, I thought it was worth the effort to get one. And actually, at the Lolin store they're only about $3.50.
Well, I guess nobody knows of another source for genuine Lolins, so if mine don't arrive in a few days, I'll probably get a clone from one of the usual sources. Banggood I guess.
I use 470uF/6.3volt or 2*220uF/6.3volt tantalum.
That already seems to reduce the ripple of the transmit spike to almost zero.
I wouldn't say "honking big" if eight will fit on the nail of your thumb.
Leo..
SteveMann:
You can buy them on Amazon and get two-day delivery. These are what I use. They aren't genuine, but they work for my projects.
Thanks. Based on the picture, the regulator marking is 4A2D, which appears to be a Torex regulator. No way to tell from the marking whether it's the 150mA version or the 300mA version.
Even though tracking still only shows them as clearing customs on the 17th, my genuine Lolins arrived in the mail this morning. The regulators are marked S2RK, which appears to be a MicrOne regulator. They also make the ME6211 shown in the Lolin datasheet, but I can't find anything on S2RK. Another shortcoming of surface mount stuff.
I have no experinece with the Mini, clone or genuine. But when I Googled Wemos D1 Mini voltage regulator, I saw several reports that seemed to implicate the regulator used in the clones in rebooting problems. Here are a couple links:
It appears the regulators are different, but I don't know if that matters. I was just trying to head off any potential problems by getting genuine Minis. I don't normally do that. I typically buy clone Arduinos, batteries, etc., but the extra cost of the Lolin parts was so small that I just decided to buy them this time.
Sounds like - if you believe Andreas, a decent 1 mF aluminium electrolytic across the 3.3 V terminal and ground would make the choice of regulator moot and any one as good as any other.
Paul__B:
Sounds like - if you believe Andreas, a decent 1 mF aluminium electrolytic across the 3.3 V terminal and ground would make the choice of regulator moot and any one as good as any other.
I don't know if Andreas is right, but his scope tracings look pretty convincing to me.
For the project I'm working on, power will come from either an 18650 or three alkaline AAs, through a P-channel mosfet functioning as a power switch, to the 5V pin of the D1 Mini, then through the Mini's regulator to 3.3V. So I was just hoping to reduce the number of things that might contribute to "sagging" during transmission. The mosfet I was going to use (LP0701) has a couple ohms of Rds(on), so I think I will go with something better than that. I saw the IRLML6402 mentioned elsewhere, and it looks pretty good.
If I have to order a capacitor, I assume a 6.3V rating would be better than something higher - less resistance, more responsive, and of course smaller.
This is a mailbox notifier thing for a friend, and unfortunately the mailbox is not only metal but also enclosed in a brick column. I think there is some (small) chance the wifi will work through all that, but if not, we'll have to look at an antenna of some kind, or moving the circuit outside. Anyway, I just wanted to give it the best chance of working through the brick, which means keeping the power steady during transmits.
ShermanP:
If I have to order a capacitor, I assume a 6.3V rating would be better than something higher - less resistance, more responsive, and of course smaller.
I would go with that.
OK, so what benefit would a rechargeable 18650 have? Presumably you intend to add solar to charge it?
The only supposed benefit of a high-side power switch is to cut out the standing current of the regulator, which is to say if you need to use a regulator. So lose the regulator instead!
I like a variation of the "button" project, which simply uses two alkaline cells - AAA in that case but AA are clearly better. It is however limited by the requirement to hold the button.
A more sensible approach is to connect the ESP8266 to the two alkaline cells, and use the control switch to actuate CH_PD. A diode from one of the I/O then holds it HIGH at the beginning of the code. When the task is completed, you drop that I/O and it completely shuts down.
No regulator, no power switch, one diode and a 100k pull-down on CH_PD (or a lower value if concerned about switch leakage or interference).
Or I suppose, a solar-charged 18650 and a series diode. The discharge curve is pretty flat in most part, so you don't really need to "regulate" it.
Well, it's a bit late to make the CH_PD change. What I have for this is the D1 Mini, which already has a regulator on it, and doesn't bring out CH_PD. And with the power being shut off 99% of the time, current used by the regulator isn't going to affect things that much.
The more immediate problem is that the D1 Mini I received yesterday won't connect to my network using the standard example programs. It just won't connect to the router. I don't know why. My computer and phone have no problem. And I don't know how to find out why.
