12V DC motor from Arduino Uno using single power source

Other Hardware Motors, Mechanics, Power and CNC
1

Hello out there!

I am newbee in electronics and Arduino stuff and I would like to apologize if the question is simple although I could not find a direct answer on the Forum.

I am building a device that will use 12V DC motor; at the moment only switching on and off is required.
For tests I have built a simple circuit like below, driving small DVD motor via 2N2222 transistor using 5V regulated output from Arduino, which itself is sourced from 9V 6 x AA basket.

836×441 96.6 KB

However at the end I would like to drive 12V DC motor, 80mA load current, 1.2A stall current, approx. 1.2Nm torque. My idea was to power both Arduino and the motor from the same 12V 8 x AA basket, using VIN out voltage pin for the motor:

849×455 99.9 KB

Does this make sense?
Thanks in advance!

2

I'd go with logic level, low Rds, N-channel MOSFET for minimal power loss in the transistor, leaving more power for the motor.
Example:

3

CrossRoads:
I'd go with logic level, low Rds, N-channel MOSFET for minimal power loss in the transistor

Thank you CrossRoads, I am also considering MOSFET, although I simply have 2N2222 in the drawer now.
But is the general connections scheme correct?

4

driving small DVD motor via 2N2222 transistor using 5V regulated output

This is not a good idea. Motors generate electrical noise that can reset or damage the Arduino, or the current draw may exceed the maximum that the internal regulator can provide. Use a separate voltage regulator between the 12V source and the motor, to power the motor.

5

You haven't said what the stall current of the 12V motor will be - you start from this when
selecting a switching device.

6

jremington:
This is not a good idea. Motors generate electrical noise that can reset or damage the Arduino,

The circuit has the diode securing it to avoid peaks of motor electrical noise. Isn't it enough? I understand that a bigger motor will produce much higher noise but the securing would be done similarly.

jremington:
or the current draw may exceed the maximum that the internal regulator can provide.

Will not in the second version (powering motor from VIN) the motor current flow aside the Arduino circuits?

MarkT:
You haven't said what the stall current of the 12V motor will be - you start from this when
selecting a switching device.

It is in the first post, the stall current is 1.2A.

Thanks so far!

7

You are guaranteed trouble if you try to power the motor using the regulated output of the Arduino, or from Vin without effective noise reduction circuitry. Feel free to try it, though!

8

Hmmm... what direction should I go then? Any recommendations? L293D?

9

The problem is power supply decoupling, which is a complex subject. It is certainly possible to do what you want but the circuit design details depend on the characteristics of your power supply, motor, motor controller and motor load.

Since you describe yourself as new to electronics, avoid these problems entirely by using separate power (or battery) supplies for the motor and the Arduino. Be sure to connect the grounds together.

10

Thank you jremington!