Attached is my design schematic.
I am using 12v 7.3aH lead acid battery to power my NEMA17 motor and arduino by putting LM7805 on the VIN pin of arduino. And rest of the circuit via 5v from arduino 5v pin.
My question is, if i remove LM7805 And directly feed 12v battery output to arduino VIN pin, and feed rest of the circuit via arduino 5v pin, will it be fine? Does the onboard ragular manage this much load? Or overheat?
Please note:
I hv one 16x2 LCD, 2 of 1k Ohm and 2 dpdt switch and drv8825 logic to be powered via 5v output from arduino,
Motor is directly powered from battery supply using 100uF capacitor for filtering
There is little commonality between a schematic diagram and pretty Fritzing pictures, the use of the latter is just trying to dumb it down to "Lego" building blocks. Pretty Fritzing pictures are useless for engineering purposes.
The on-board regulator barely has enough capacity to power the Arduino and a few LEDs. You don't say which NEMA17 stepper motor you are using, but the specs range from 300mA to 2.3Amps.
If you try to power your motor from the Arduino 5V pin, you will likely damage the on-board regulator.
The LM7805 is rated at 1amp and at that capacity probably should have a heat sink on it. Also no filtering capacitors are shown on the drawing, could be some issues with erratic operation.
If it's indeed an Uno (Fritzing is misleading), then 5volt on V-in is not enough.
V-in needs between 7 and 12volt for the already built-in 5volt regulator to do it's job.
If you DO want to use that external 7805, then connect it's output to the 5volt pin.
You MUST use two capacitors on the 7805, to prevent it from oscillating and possibly destroying things.
A 5volt buck (switching) converter would be better (no heat).
Or power the Uno with a 5volt cellphone charger, connected to the USB socket.
Leo..
Wawa:
If you DO want to use that external 7805, then connect it's output to the 5volt pin.
No actually, that's my question, i do not have 7805 and i don't intend to use it. I want to use 12v battery to feed arduino because i will be using this setup in remote area where i can not supply arduino with external USB or laptop. So i want both motor and arduino to be powered with one 12v lead acid battery, But somewhere i read if battery voltage is greater than 12v (which could happen at full charge) at vin, and if arduino 5v output is drawing more current the onboard voltage regulator can overheat and damage. That is the reason i posted frizing drawing to give idea of wht is connected on 5v output and if its sufficient or more for arduino to manage.
(brushed) DC motors only uses power when they move. A stepper always uses power.
Are you sure a stepper is the right choice for battery power?
As said, a 5volt buck converter could be a better choice.
About half the current draw from the battery than an external 7805 or Arduino's built-in regulator.
Leo..
So you absolutely need a proper 5 V "buck" regulator rated adequately to provide your 5 V supply to the Arduino "5V" pin and all other modules which require 5 V.
How are you going to charge the battery every day as it will clearly require?
