What battery is best for Arduino Pro mini with nRf24L01

Hi,
I am currently building my RC car project using pro mini. But have some power issue to the pro mini.

My project:

  1. Pro mini 5v with 2 x ps3 joysticks and nRF24L01+ to transmit my control signal(forward/backward, left/right) to the RC car.

  2. Pro mini 5v with nRF24L01+ as receiver for my ESC and servo, it also control lighting for my car as well.

My sketches for TX and RX are done and fully tested with UNO and no problem with it, working perfectly fine and I am happy with it.

Because I want to save space and make it compact, so I had design my own schematic diagram and implemented on pro mini. I know nRF24L01 only need 3.3v supply, in my board I have step down the supply from 5v to 3.3 for nRF24. After everything had soldered properly and power it up, both Transmiter and Receiver board are not working, receiver not receive any signal from my transmitter.

My power supply for receiver is powered by the car ESC which supply me 6v.

My power supply for transmitter is powered by a 9V battery.

When powered from UNO 5V supply to my transmitter, it work and receiver finally receive the signal and worked.

My question is, what kind of power supply I have to use to power my pro mini with nRF24L01+ so that I can have "clean" 5V supply?

Where is the fault? Transmitter or receiver? Find out.

Have you measured all the voltages at every point on the circuits?

Hi

Add a 47 or 100uf capacitor close to the VCC and ground of the Rf24. A voltage reg often can't cope with the instantaneous current draw of these transceivers so the capacitor will sort that out.

I had exactly the same issue as you and the cap fixed it and testing it needing a minimum 47uf electrolyte cap to work reliably.
Regards

Phil

a 9V battery is a most poor choice for an uno project as it is capable of perhaps 50mA for 1.5 hours as the battery capacity rarely exceeds 100 MAH max
A 2S 1000 MAH Li-Po is IMO the minimum that can be used for long term rechargeable use with an Arduino 5V linear regulator as it causes the least amount of regulator power dissipation or power lost. I buy 7.5V 2A wall warts for my projects that require AC power
For my own use I prefer a buck boost mode switcher to convert the 4.2V max of a single cell to 3.3 V output and use my project @ 3.3V. Although buck boost converters rarely exceed 85% efficiency they are Much better than a power supply derived from a linear regulator
AS has been mentioned the Arduino 3.3V source is only capable of perhaps 50 mA and has one (C13 or C14) 1 uF capacitor for the bypass capacitor for the LP2985 3.3V linear regulator depending on the board.
Once as a test I connected a GPS receiver to a Pro mini and viewed the time from TinyGPS++... No LCD just the serial Monitor...
It lasted for 2 hours before the GPS device failed and this was with a buck mode switcher to convert 9V to 3.3V..
About 35mA for the PRo-Mini and 30 mA for the GPS U-Blox NEO 6 receiver..
3 AA cells connected to the Vcc connection operated the thing for 3 days (probably used batteries too)..

Doc

What are you using to step down your voltage to 3.3v? I initially tried with a linear regulator (7805) which does not work. You need to use a LDO, something like TPS7133.

Riccarr:
What are you using to step down your voltage to 3.3v? I initially tried with a linear regulator (7805) which does not work. You need to use a LDO, something like TPS7133.

I am using LM117 voltage regulator and added 2 x 10uF capacitors, one between Vin to Gnd, one between Vout to Gnd. It give me a stable 3.3v to my nRf24L01

hi guys,
Thank for all the advise. I finally figured out and managed to get it work fine. Below are some pic of my TT02 project. I used 9v battery for my transmitter. For the receiver from my car, I have to separate the board and the ESC/ servo battery. I tried to use the BEC from the ESC but everytime I throttle my car, the voltage drop rapidly to less then 3-4v which end up switch off my pro mini and cause my car to stop receiving signal. So I solder a separate connector to isolate the power source between the ESC/ servo and my pro mini. And it work fine. I still have to figure out how to re-design my board to be able to use the power source from BEC rather than using separate battery source to play my RC car.

Hi dear airwinx.

Can you share the arduino code on your RC car project, please, for me? cokemon18@gmail.com

Regards!
Thank you