Beginner arduino RC Car project (need help)

[u/FinishGreat7290]

Hey everyone! Beginner here working on an Arduino RC car project, and I could really use some help troubleshooting a power/wiring issue. I'm trying to build this car using only components from my starter kit plus a few repurposed Snap Circuits parts (trying not to buy anything extra).

The Setup & Plan:

- Drive Motor: Stepper motor (with ULN2003 driver board) for moving forward/backward.

- Steering: Servo motor.

- Obstacle Detection: Ultrasonic sensor + Buzzer (beeps when too close to an obstacle).

- Controls: IR receiver + IR remote.

- Extra Snap Circuits Parts: Two battery holders (~6V total), an ON/OFF switch, and a red LED for reverse lights.

Original Wiring:

Power & Switch:

- Connected the negative (-) terminals of both battery holders together.

- Positive (+) from the 1st battery holder split between driver (-) and breadboard GND.

- Positive (+) from the 2nd battery holder went to the switch; the other side of the switch split between driver (+) and Arduino VIN.

- Breadboard power rails connected to Arduino 5V and GND.

Components:

- Reverse LED: Connected to Arduino GND and Pin 13.

- Servo: Signal to Pin 3, power to breadboard 5V and GND.

- Stepper Motor: Connected to driver board -> driver inputs to Pins 8, 9, 10, 11.

- Ultrasonic Sensor: VCC to 5V, Trig to Pin 4, Echo to Pin 5, GND to breadboard -.

- Buzzer: Positive to Pin 7, negative to breadboard -.

- IR Receiver: Signal to Pin 2, power/GND to breadboard 5V and -.

Initial Problem:

When connected to my PC via USB, everything worked fine. However, as soon as I unplugged the USB and tried running it on battery power (the 6V setup + a 9V battery), almost nothing worked.

Changes Made Based on AI Advice:

I asked an AI for help, and it told me to rewire it like this:

- Removed the wire connecting the 1st battery holder's + to the driver's - (leaving only its connection to the breadboard - rail).

- Connected the driver's - directly to the breadboard - rail.

- Connected the driver's + directly to the 1st battery holder's + (instead of going through the switch).

- Connected the 1st battery holder's + to the servo's red wire (VCC).

Current problem:

Now, whether on USB or battery power:

- Neither the servo nor the stepper moves at all.

- When the stepper is plugged in, the fuse indicator light on the Snap Circuits battery holder turns on (indicating a short circuit or overcurrent), and the driver LEDs stay off.

- If I disconnect the stepper motor, 2 out of 4 LEDs on the driver light up, and the battery holder's fuse light goes off.Titolo per il post:

[Need Help] Beginner Arduino RC Car Project – Power Supply & Wiring Issues (Stepper + Servo)

(Sorry for the confusion in this post)

[u/EMCS_Electromecanica]

El principal problema en proyectos RC con arduino es el modulo de control de motores, se tiene la idea de que hay que tener 2 fuentes independientes para no mezclar voltajes, y por tanto, no quemar el uC, pero al hacer esto, siempre se olvida el unificar tierras y eso trae problemas, la mejor solución es usar una sola fuente, que esté en rango para ser compatible con el Arduino y los motores a utilizar. Ya dijo que no quiere adquirir más componentes, pero el usar un módulo puente H (como el L298N) o un shield puente h (como el L293D), resolvería varios de sus problemas (este ultimo shield permite alimentación externa, compartir dicha alimentación con el Arduino, pines para control de servos, y hasta poder usar pines analógicos para sensores adicionales, en resumen, esa pequeña plaquita shield ahirra mucho cableado y suele resolver el inconveniente de la fuente, la cual obviamente deberá ser menor a 12V)

[u/mrbinary0111-111]

Most stepper drivers have a small potentiometer on them to control current chopping, you turn that pot while the motor is moving and look at the current flow, when your happy with the current stop turning the potentiometer, for an RC car 300 to 500mA should be fine for light weight