charlieplexingdpdtmotorrelay
I build a project using 8 relays in a matrix (charlieplexing) to control 16 motors (actuators), plus one relay to control two DPDT relays to reverse the power for the motor to turn reverse. I only need to run one motor at a time.
When testing it i found that current will run though the motors and start other motors in the grid.
Is there anyway this would be able to work or do I need a relay for each motor?
You can use any 12v speed controller that accepts a PWM signal. There are many such controllers available. Check eBay and google.
What you will be doing is using the PWM signal from the arduino to control a speed controller that is "regulating" the voltage to a motor. This way the power source for the motor is completely independent from the arduino.
Personally I have experience using Talun and Jaguar speed controllers. Those are both very expensive, but they will give you an idea of where to start looking.
When we look at the internal circuit diagram of the relay it looks like the following:
I have also added one motor to show how the connections are to be made.
Vcc is the signal given by the microcontroller (one of the output pins from the Arduino). When this signal is given the SPDT switch changes state to NO. This completes the circuit and the motor will rotate.
Note Vcc is just a 5v signal if from the microcontroller (Assuming this is the rating of the relay). But Bat2 needs so supply the required voltage and current for the motor to run.
Now moving onto what you want to achieve in your project, the description is vague. You are running 2 pairs of motors with 4 Relays. I presume each pair is controlled by 2 switches. One for moving forward and one for moving backward. The same for the other pair.
The circuit diagram looks like the following:
Truth Table: U1 - M1 and M2 Forward
U2 - M1 and M2 Backward
U3 - M3 and M4 Forward
U4 - M3 and M4 Bakcward
U1 and U2 - Nothing
U3 and U4 - Nothing
All other combinations can be inferred as M3 and M4 are isolated from M1 and M2. You have to make sure your battery can handle running all 4 motors at once though.
Best Answer
After several iterations (which can be seen in edit history), I think this arrangement is optimal for practical reasons: it requires the smallest number of separate relays to drive (7 relays), and they can all be of the same commonly available type DPDT.
To enable a motor, K1 and K2 are used to select the correct column. Then K3-K6 are used to select the row. The lower end of all other motors on active column gets disconnected, ensuring that no current flows through them. Finally, K7 can be used to reverse direction.
simulate this circuit – Schematic created using CircuitLab