Yes, it’s missing! I didn’t notice that error before, I’ll make sure to fix all the schematics in the next eBook update. Thanks for letting me know.

Ok, so no stupid question of me. I thought “a common ground” is so common that a random nerd will not bother about such a trivial point. 

But I have now a more serious problem:
I connected my tested LoRa_Sender circuit to this Solar circuit, with a common, a battery sensor wire (I used GPIO 34) and the plus (from the 3.3 out of the LDO regulator but my ESP32 is staying dead, no lead is burning. I measured the voltage from the LDO and hits 3.31 V.
O, I connected to the 3.3V pin on the ESP32. Or should it go to the VIN? Your schematics say V3.3.

Excluding that my new Lion-battery was too low in power, I charged it. As wel by solar energy as later on by USB connector that is present on the TP4056.

But no result. Of course I checked my connections. I pressed the EN button several times.

Do you have any idea or a good suggestion?
Kind regards,

  Jop

Hi Jop.

Yes, the GND was missing. It was already updated in the online version of the course. The updated eBook will be released next week.

Regarding your question…

The output of the LDO should go to the ESP32 3.3V pin.

Are you using an ESP32 + LoRa module or the ESP32 with the LoRa transceiver module built-in?

What are the specs of the battery you are using?

If you upload a blinking LED sketch, does the ESP32 work with the solar circuit?

Regards,

Sara

Howdy Sara,

Thanks for your ongoing interest in my project.

I saw you or Rui corrected already all the schematics involved with missing GND. Very good. You are very punctual.
My question…. yes it is working now with an ESP32 DOIT (the one you use in all examples).
Actually it was my own stupid fault. To simulate the batteryvoltage (before I went over to the Solar circuitry) I connected a slider potentialmeter, but wrong (changed slider and end pin), so this sliderpot was pulling down the battery-input.
Here specs of my battery: https://www.tinytronics.nl/shop/en/batteries/18650/panasonic-18650-li-ion-battery-3350mah-6.7a-ncr18650b

Brings me on question how to connect this EPS32 LoRa builtin of TTGO (Version 1).
That’s this one: https://www.banggood.com/2Pcs-Wemos-TTGO-LORA32-915Mhz-ESP32-LoRa-OLED-0_96-Inch-Blue-Display-p-1239769.html?rmmds=search&cur_warehouse=CN
This board has at the back side this power supply possibility with (see link and two wires red and black)

Good documentation for this board is poor and hardly to find on the internet.
I think this is working as an LDO (so we can connect here an 18650 Li-battery with 4.2 Volt).
It seems this is also a charging circuit.  But how to combine this with solar panels according your example project.

Can I use the LDO-exit of your solar circuitry and connect here also to the 3.3V-pin?
Or shall I connect the Li-battery direct onto these two cables?

Thanx for your attention.

Jop

Hi Sara,

In follow-up of my last post discussing how to powering this Wemos TTGO by using its own “power feeding wires” (at backside of this board) in combination with your Solar Power station, is this maybe a possible solution?
I skipped just the whole LDO-circuitry as it seems to me that the Wemos TTGO has this aboard.


It seems that this TTGO-powering input can have voltages up to 7 Volt.

Kind regards,

   Jop

Hi Jop.
If it can handle up to 7V, you can power it directly from the battery, without the need for the voltage regulator circuit.
So, yes, I think you can do that. Then, let me know if you succeed!
Regards,
Sara

Hi Sara,

Here a positive post (no SD-troubles). You wanted to know if skipping the LDO circuitry is successful when using the TTGO ESP32 LoRa board.
Yes. Works good.

Here my Solar Powered simple Weather station – some pictures.

As you can see on 3rd picture no LDO-circuitry. The extra power wires  of this TTGO ESP32 LoRa-board  (Version 1) connected straight with the Lion 18650 and the charger output. Battery can unload to somewhere 70 – 75% before sender is dying.
Last picture is Google Sheet collecting data with IFTTT. Thanks for your nice explanation IFTTT somewhere on RNT.
It’s a pity that IFTTT allows only 3 fields. So I collected less important data in one column.
As you see, because of the added RTC each sample is done at exact every 3-minute-interval. Just for test – later on I will change this to 10 minutes and then it is synchronizing with output from official Dutch Weather Forecast KNMI.

Have a good day,

    Jop

ps BTW, what’s the best way to put a sketch in a post with this pastebin.com? I struggled yesterday with that. How I can get this scrolling window around my paste code?

Hi Jop.
Great news! Your project looks awesome! And the extra waterproof reset button is a very nice addition!

With IFTTT you can only post 3 fields. We’ve recently published a post on how to publish data to your own server. It can be useful to publish as much fields as you want and access it from anywhere in the world. Here is the project:

• https://randomnerdtutorials.com/esp32-esp8266-mysql-database-php/

When posting the code with pastebin, you can only share the link.

The scrolling window around your code is edited by us manually, after reading the questions.

I’m truly happy to see your project! I’ll answer your other question about the SD card in the other topic.

Regards,
Sara