Hello,
Im attempting to supply power to an arduino nano and a small servo (4.8v - 6v) with a single battery source (9v block). My plan was to use a polulu 5v regulator between the 9v battery and the servo, as well as a direct connection from the 9v to the arduino's V in pin. Ive attached a simplified diagram.
The arduino would additionally be powering a few small LEDs, but only one would be active at a time. There would also be a joystick connected to the 5v out pin of the arduino.
I just wanted to check if the concept of splitting the 9v battery lead to the arduino's V in and to the 5v regulator is valid, and if any consideration needs to be made regarding the grounds. I would do a simple test myself but Im waiting for the 5v regulator to arrive and I wanted to get ahead of any issues that might require a redesign.
Hope I dont sound too stupid, still learning and trying not to fry anything!
I think it will work. The only reservation is the current drawn by the servo, including in particular when power is first applied to it. In my experience, even little servos can draw several hundred millamps in the process of initializing, regardless of the state of the control line. You'll just have to try your setup and see if it works. The grounds would all be common, as you have it. The basic question is all about current. Either your battery and regulators will supply enough, or they won't.
I do hope that when you refer to a "9V block" battery, you do not mean the "PP3" battery implied by your diagram!
I also hope you do not intend to use a 7805 regulator - which would require input and output bypass capacitors as well as a substantial heatsink - but are ordering a proper switchmode "buck" regulator module.
Paul__B:
I do hope that when you refer to a "9V block" battery, you do not mean the "PP3" battery implied by your diagram!
I also hope you do not intend to use a 7805 regulator - which would require input and output bypass capacitors as well as a substantial heatsink - but are ordering a proper switchmode "buck" regulator module.
Hey Paul,
I was intending to use an Alkaline 9v battery (the typical one shown in the crude tinkercad diagram) but Im glad you raised an issue with it! What exactly would be the problem with that and what similarly sized options would be better? If it helps, Im not very concerned with how long of a useful lifetime I would get from it, it would have a short operating time of only a few minutes at a time.
As for the regulator, no I was not planning on using the one in the diagram, its just the only provided module in the tinkercad interface (Fritzing has been crashing every time I try to open it these days). I was planning on using a polulu 5v regulator (https://www.pololu.com/product/2119). I hope this is a more acceptable regulator for my purposes.
Thanks again for raising a red flag, exactly why I posted here!
Thank you both for your answers!
I just tested my setup and the servo does seem to draw too much current causing the arduino to reset when the servo moves. It seems to be right on the edge as about 50% of the time, both the servo and the arduino operate normally, but this is certainly not acceptable.
Would 6 AA or AAA batteries in series have the same issue?
My main issue is that I have extremely limited space to fit my power source so the smallest possible battery / array of batteries would be ideal.
"Would 6 AA or AAA batteries in series have the same issue?"
Four AA or AAA alkaline batteries in series would provide ~6v, which could power the servo directly, and a small diode in series between the batteries and board would provide ~5.3v to the board, which the board might be ok with.
Or 4 x NiMH rechargeable AA or AAA (Eneloop or similar) will provide approx 4.8V which will directly drive both servo and Arduino. And they generally handle more current than equivalent size alkaline batteries.
Thanks all! I just tested with 4 AAA batteries going into the polulu 5v regulator and I connected both the servo and the arduinos 5v pin to the regulated output. It seems to work without issues, I just wanted to be certain that current spikes from the servos wont have a negative impact on the voltage going to the arduinos unregulated 5v pin. I also tried (accidentally) connecting the 5v regulator output to the arduinos Vin pin, which also seemed to work. This confuses me slightly as the arduino specs says that the voltage to Vin should be between 6v and 20v...
Any tips for which setup would be preferable?
The polulu regulator is a step up / step down so hopefully when the batteries get low the voltage should get stepped up to 5v.
Connecting 5 V to "Vin" will lose about 1.5 V by the time it gets to the logic. The Arduino will mostly still work at this level but would be very flaky.
