problem with dcMotor circuit

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello
I am try to build this circuit Arduino Playground - DCMotorControl

I didn't understand the circuit, How I should connect the relay?

How the Transistor get a voltage?
There are some problems with this circuit.

thanks

2

The circuit diagram is wrong. The relay coil should be on digital pin 3, according to the code. There must be a diode across the relay coil to protect the Arduino.

How I should connect the relay?

Connect the coil of the relay to Arduino pin 3 and to ground. In addition, connect a diode across the relay coil to protect the Arduino (anode to ground, cathode to Arduino pin 3). Cross-connect the relay contacts to reverse the polarity of the motor. Connect the common contacts of the relay to +12V and to the transistor's collector.

How the Transistor get a voltage?

The transistor is connected from the relay coil to ground. The base of the transistor is connected to the Arduino pin 11 via a resistor.

This circuit diagram is wrong in many ways. How should we go about fixing it?

3

thanks.
maybe, You have valid design for this curcuit?