💬 Easy/Newbie PCB for MySensors

[dbemowsk]

So a question I have always wondered about the voltage regulator is do you really need to desolder it if you connect your incoming power to the 3.3v pin and not the RAW pin? I would have thought the regulator would only drain power if it was converting the RAW power down to 3.3v.

[sundberg84]

@dbemowsk - your logic sounds right, but i think it will draw power anyway... only way to figure out is to measure or google :)

[popunonkok]

I managed to change my PCB order, I saw that one of the updates to rev9 was the ability to use Pin 2 as GPIO instead of going to the Radio where it is unused. So now I have a order for Rev9 instead.

I will try to desolder the led or resistor and the voltageregulator.

Thanks for sharing your design.

[sundberg84]

@popunonkok Good luck - let me know if there is any other questions.

[Nca78]

@dbemowsk in fact current is leaking through the regulator when its input is floating, you can check the "reverse leakage current" value on the data sheet of the linear regulator used on your promini boards then decide if you can accept it or not, depending on your circuit.

[ileneken3]

Hi -

I wanted to know if this config is OK:

Attach a LIPO battery to PWR and GND.
Cut off the right side of the board.
Use a 3.3V pro mini.
Add a regulator (like a MCP1700) and necessary caps. (Spec says 1uF).

The idea is that the board and sensors get 3.2V - 4.1 V (which should be OK).
The radio gets 3.3V.

Thanks!

[sundberg84]

@ileneken3 - sounds right, you should short the jumper REG which will feed everything the LIPO voltage. If this is higher than 3.3v I dont know what will happen but adding the voltage regulator for the radio will make sure that one is ok. I dont know about the pro mini, it it can handle up to 4.1v but I guess you will find out.

[gohan]

I'm curious too if will handle the 4 volts or not😀

[Nca78]

No problem with the promini. Limit is from atmega and it's 5.5V I think (at least 5V anyway :) )
You will just have HIGH level voltage at battery voltage at the outputs instead of 3.3V

[gohan]

So technically you can power a 3.3V pro mini with a LiPo battery, you only need a regulator for radio, correct? Can you still make reliable battery voltage measurement? I Have a NRF24 adapter with a AMS1117 onboard, will that still work or does it need 5v?

[Nca78]

@gohan said in 💬 Easy/Newbie PCB for MySensors:

So technically you can power a 3.3V pro mini with a LiPo battery, you only need a regulator for radio, correct?

Correct.

Can you still make reliable battery voltage measurement?

Yes, check here :
https://forum.mysensors.org/topic/186/new-library-to-read-arduino-vcc-supply-level-without-resistors-for-battery-powered-sensor-nodes-that-do-not-use-a-voltage-regulator-but-connect-directly-to-the-batteries

I Have a NRF24 adapter with a AMS1117 onboard, will that still work or does it need 5v?

From the datasheet typical dropout voltage is 1.1V and it can be up to 1.3V.
So to get 3.3V at the output you need at least 3.3 + 1.1 = 4.4V. It won't work with your battery, you need to use another voltage regulator with a much lower dropout voltage.

[ileneken3]

@Nca78

At least according to the specs, mcp1700 will do the trick (both in terms of drop out voltage and low power consumption for battery usage). I will try it.

[gohan]

I have seen these boost/buck converters https://www.aliexpress.com/store/product/5pcs-mini-1-8V-3V-3-7V-5V-to-3-3V-Boost-Buck-Low-Noise-Regulated/1525466_32365767349.html

https://www.aliexpress.com/store/product/2PCS-Auto-Buck-Boost-DC-DC-Converter-Voltage-regulator-module-0-9-6V-to-3-3V/1525466_32757272432.html

Would they make any sense to use with LiPo batteries or other solar power source to power a node? Or would they waste too much energy?

[ileneken3]

@ileneken3

Regarding the MCP1700 as a regulator (I ordered these: https://www.aliexpress.com/item/5-pcs-MCP1700-3302E-TO-MCP1700-Fixed-LDO-Voltage-Regulator/32781100568.html)

first connected the LIPO->TP4056->MCP1700 to the GND and PWR of the board. (I made a homemade little regulator board). From all appearances, it works great, and I end up with a nice compact sensor/battery. But I want to make use of the Easy/Newbie board. I tried hooking it up to the 3 pins marked regulator, but it didn't seem to do anything. Am I missing something? The orientation can be confusing, but I think I got it right. I measured 4.1 volts to the radio, which will fry it.

Thanks!

[sundberg84]

@ileneken3 - the board is created for Le33a voltage regulator which has a different pinout than yours.
You have to adjust to that and not just put it in according to the pcb.

[ileneken3]

@sundberg84
I did adjust to the different pinout. I checked it multiple times, checked soldering - it always seems like the regulator is not regulating anything - the radio always gets 4.1 volts from the LIPO.
From looking at the specs, the LE33 is pretty close - with the biggest difference that the MCP1700 can handle more current.
Maybe I should just get the LE33 ones.

Oh well...

[Nca78]

@ileneken3 your problem with le33 will be the quiescent current which is high, datasheet says "typ. 50 μA in OFF
mode, 0.5 mA in ON mode, no load". 0.5mA will not give you a good battery life...
Compared to a typical value of 1.6µA on the MCP1700 (max at 4µA), you should stick to it if you are using a battery.

Did you test the MCP1700 on a breadboard ?

[dbemowsk]

@ileneken3 Can you post a pic showing how you have this wired? preferably the side where your battery is connected. I would like to see where you have your battery connected and how you have the board wired.

[ileneken3]

@Nca78

Yes, I agree. I didn't look closely enough at the currents for le33. The general rule of thumb seems to be:

Current in "milli"amps -> only days or weeks for a battery
Current in "micro"amps -> months on a battery

So MCP1700 seems to be right for a LIPO here.
I did test it on a breadboard. And then I built a little regulator board. It works great.. and I used a battery from an old cell phone that stills seems to work well.

[ileneken3]

@dbemowsk

There's not much to the wiring (maybe that's my problem?).

To attach the legs to be like a LE33, I swung the Vout of the MCP1700 all the way to the left.

With a multimeter, I see 4.1 volts at the radio, and everywhere else.

Thanks!