That is not necessarily valid. It's a digital circuit- it takes current in spikes and fits, which is what the bypass caps are also for. An easy way to tell is put a 1-ohm resistor in series with ground and measure the voltage drop across it- this will give you the true current being used.

nrf52832 based module, it doesn't have 6v VIN

 

link to the buck converter?

 

link to the buck converter?

https://www.amazon.de/gp/product/B07MY2XP21

 

Capacitors will help you, any way you go.

Ok let me solder, try and report back. Any source I can read on which capacitor to use or suggestion ? thanks

 

Datasheet of your module maybe.

Module datasheet
https://forum.mysensors.org/assets/uploads/files/1499826952956-e73-2g4m04s_datasheet_en_v1.1.pdf

Servo datasheet
https://www.electronicoscaldas.com/datasheet/MG996R_Tower-Pro.pdf

 

The buck converter says do not use with a light load or a load below 10% of it's output which would be about 300ma.'
Better off using a simple linear regulator. Available at Amazon.

 

those are two setups I tried with the Buck. both didnt work, as I said, servo moves a bit when powered from single source like 10 degrees instead of 90.
Microcontroller doesn't shut down.

Servo is MG996r Stall Torque: 9.4 kg/cm @ 4.8V. Stall Torque: 12 kg/cm @ 6V. Running Current 500mA - 900mA @ 6V. Stall Current 2.5A @ 6V.

@alex116

Okay, so BlueTooth Tranceiver is >50mA (recommended), and servo-motor requires 2.5A. So your power-converter has to provide at least 2.6A downstream to be sure it can provide enough current for whatever. I see you're using the MP1584EN. Now you need to do the calculations on the MP1584EN, so you know what power is on the upstream side (that is required) in order to get out of it what you need.

Please show that you've worked through the equations in the datasheet (starting on page 9) so you know what components to use around this specific BUCK, or have you just been guessing in the dark?

 

Please show that you've worked through the equations in the datasheet (starting on page 9) so you know what components to use around this specific BUCK, or have you just been guessing in the dark?

I believe the TS is using a complete module not the just the chip.

 

thanks sghioto,
indeed, I use complete module

 

Just got to love those useless datasheets. I would put a small ceramic and a larger electrolytic found in the junk drawer.

quick question, would it be suitable to use 10 uF electrolytic capacitor for the microcontroller only (2 AA-s) and 100 uF electrolytic for the servo (4 AA-s bat.) ?

and how that will affect overall battery life of this device?

 

The capacitors don't have anything to do with the battery life. That depends on the average amount of current they use in an hour. Example, the micro says 5ma on RX and 14ma on TX so maybe about 10ma average or about 240ma per day. Using 2200ma batteries might last appx a week. Same applies to the 6 volt battery for the servo.

 

I believe the TS is using a complete module not the just the chip.

I saw 2 datasheets, a Module- which is a BlueTooth Tranceiver, and a Servo. I did not see a datasheet for the Buck/converter which is why I posted one for it. The Amazon page the TP lists the BUCK converter on only shows ideal ratings, which are only outside ranges. You have to go through the datasheet and do the calculations to determine if the BUCK converter will even satisfy your constraints.

If he does the calculations, he may determine that his input must be 12V, not 6V, because the energy he wants output is primarily amperage, which means it has to come from somewhere. His input is low-amps, so that difference must be made up in volts, and 6V probably won't cut it.