I’m working on a project. It’s acually an automotive project. I want to control 2 throttle bodies that use 5V stepper motors. A little background: The motor is driven by a sg3525pwm chipset that is integral to the vehicle’s ECM. For input there are 2 5V potentiometers in the pedal assembl and 2 position sensors on the throttle body itself.
I don’t want to break into the ECM to gain access to the chipset. So, is their a way to control 2 motors with the modulated signal?
Chris
Will an h bridge drive 2 motors without needing amplifications?
You don’t want to parallel the steppers. You need to get at the drive signals to the stepper drivers.
Can I use the driven circuit on the inputs of a h-bridge? Then drive the motors with the 2 outputs?
Hi Chris,
As **KM6VV **already mentioned, you do not want to set your stepper motors in parallel on the same final output stage (the h-bridge/controller chip output to the motor).
Instead, you should have a dedicated controller/h-bridge/chip for each motor and send the proper digital signals to each of them.
If we understand properly the solution you are proposing, it would go something like this:
This may work, but one of the potential issues is that most h-bridges/driver chip package expect digital inputs, not high-current motor type outputs to come in.
A better solution would be something like this:
Sincerely,
Thank you for your response. Your answer is exactly what I was looking for. I had a suspicion that your second flow chart is what I needed. My next question is how do I go about converting the high output signal to an input? The SG3525 is integral to the ECM, no way of isolating it.
Chris
Hi Chris,
A possible option then would be to convert those outputs of the SG3525 to drive two h-bridges connected to your motors directly.
An example setup would be:
The dotted lines between the SG3525 and the H-Bridges requires a few extra components other than simply wires.
Some considerations include:
]A resistor in series to act as a current limiter./:m]
]A small, low gain transistor (could be any of the very small ones) that would be driven by the outputs of the SG3525 for each digital input needed./:m]
]All the appropriate pull-up/pull-down resistors to make all of this work / act as wanted when no signal is given (breaking/holding)./:m]
Therefore, while this is not impossible, it will require some thinking, tinkering and ingenuity. Going into anymore details than this exceeds our support level, but feel free to post schematics or ideas for the RobotShop community to help with.
Another place where you may receive good help on this would be our project-oriented website, Let’s Make Robots.
Sincerely,
