Electronic Speed Controllers for DC Motor

[Gdeaver]

If you can do a little breadboard wiring and reprogram the pwm port you might want to take a look at the SN754410 DC motor drive chip. It can control 2 motors. 2 inputs control the direction and the enable line can control speed by driving it with a fixed frequency PWM. Vary the duty to control power. You'll have to modify the default code to change the hardware PWM for the frequency and then add code to change the duty.
This app note is for basic but gives an example.http://kronosrobotics.com/an101/DAN101.shtml The same chip can controll stepper motors too. It could also drive Fets for higher power.There are also chips that can generate the PWM and monitor current for curent limiting. They are harder to implement. Note the warning about the 10000K resisters inline on the inputs. This chip is not isolated and if it fails there could be drive voltage on the inputs. The resistors povide some protection.

[Spindle]

Ok I am a bit confused, I am am going to get this product Dual 5Amp Speed Controller - Carbide SOZDSCR2.3 at http://robotcombat.com/marketplace_soz.html will it work. I know it can control up to two motors independatly and it will hook up to my motor, battery, and pwm outputs from the EDU RC. My question is that I am running a 7.2volt battery of course and my dc motors are rated for 3-9 volts. I want to run the motors at 7.2 volts. Will the voltage be truncated down to 5volts or will the DC motors ends up getting the 7.2 volts from the battery. I need to know before I make the purchase.

[seanwitte]

Originally Posted by Spindle

Ok I am a bit confused, I am am going to get this product Dual 5Amp Speed Controller - Carbide SOZDSCR2.3 at http://robotcombat.com/marketplace_soz.html will it work. I know it can control up to two motors independatly and it will hook up to my motor, battery, and pwm outputs from the EDU RC. My question is that I am running a 7.2volt battery of course and my dc motors are rated for 3-9 volts. I want to run the motors at 7.2 volts. Will the voltage be truncated down to 5volts or will the DC motors ends up getting the 7.2 volts from the battery. I need to know before I make the purchase.

It should work, but you will need to do two things:

1. Build a wiring harness to split the battery into two leads in parallel. One goes to the ESC and the other to the robot controller.

2. Read the manual and disable the BEC on the speed control.

[Spindle]

Would I just have to splice the battery wires having one go to the ESC and the other to the EDU RC or is that in series? If you have a link to a wiring harness similar or a diagram that would be much appreciated. Also for the BEC I know its on the ESC but is it also on the EDU RC? Does 7.2 volts come out of the EDU RC PWM Outs or is it 5.0 volts. I needs to be 7.2. Thanks again!

[seanwitte]

I would order a few male and female battery connectors from IFI. Cut two red wires and join them at one end. Do the same with the black. The ends you joined together will go into a female connector that will mate to the battery. One of the free pairs gets a male connector and plugs into the rc, the other goes into the terminal block on the ESC.

Now you have power going to the ESC so you need just the signal. The ESC will be powered from the battery. If you cannot disable the BEC on the ESC then the best thing to do would be to get a servo extension and disconnect the red lead. The rc only needs to supply signal and ground, not sure how it would react to the BEC input.