Hello, I am relatively inexperienced with electric circuits and am wondering if the attached circuit will work or if there is a better way to run the motors.
I had a similar setup and fried a raspberry Pi I believe caused by not having the reverse voltage connector when using the change over switch.
I don't know what effect the buck converters have on the rest of the circuit if any and I am unsure if the 24v capacitor is needed or setup correctly in the circuit. I would be grateful for any advise people can offer.

 

That wiring diagram contains several cross-polarity connections. THAT WILL CAUSE PROBLEMS What will be useful is a description of what it does, or what you want it to do. Otherwise you will get random guesses.

 

I suggest you use one of the free schematic capture drafting PGMS such as Kicad to make it easier to see what is going on.

 

The aim is to have the Pi control the stepper motors at all times and the brushed motor when the switch is in phase 1. Phase 2 and 3 are for manually controlling the motor in both directions. I want it to all be connected to one battery.
I will give Kicad a try and reupload the diagram

 

your present circuit will not work. there is no connection from controller to drives. only power distribution is shown. even if the power distribution is done correctly (mistakes only in the presented schematics) there is no way for controller to control any of the motors.

 

The capacitor is connected wrong. (the only part of the diagram I can understand)

 

Your diagram shows two direct short circuits across the output of the reverse voltage protector. If you breadboard it like that you will see some smoke and sparks!

 

Hello, I am relatively inexperienced with electric circuits and am wondering if the attached circuit will work or if there is a better way to run the motors.
I had a similar setup and fried a raspberry Pi I believe caused by not having the reverse voltage connector when using the change over switch.
I don't know what effect the buck converters have on the rest of the circuit if any and I am unsure if the 24v capacitor is needed or setup correctly in the circuit. I would be grateful for any advise people can offer.

View attachment 354215

Here is a version of the drawing that looks like it scales better on a computer screen. Let me know if it is not any better on your screen when you zoom in and out. It should be easier to read.

 

As already mentioned, the drawing only shows power connections, and those are wrong.Not one bit of control connection. Itis not even an adequate flow chart!!

 

Welcome to AAC.

As a rule, "wiring diagrams" are a poor substitute for schematics and are very hard to read in place of one.

While you did provide a short narrative on what you expect your project to do, it is much more likely to result in a successful outcome if you ask your question about the problem you are trying to solve rather than about the (self-labeled naïve) solution that you have concerns about.

It is OK to indicate constraints based on parts that are a given—possibly because you already bought them—since if you have them and must use them they are now part of your problem rather than the solution.

This seems to be a relatively simple project but it is hard to tell if making your proposed scheme "work" with actually solve the problem or not.

Good luck!

 

Some casual observations:

1) If I understand how you intend your "changeover switch" to operate, in two positions it will connect 24V directly to the motor and the outputs of the DRV8871 motor driver. That will power the driver through the body diodes of the output MOSFETs, and might be a bad day for the driver.

2) The + wire is shorting the "24V capacitor", so it's not doing anything.

3) Assuming all the indicated specs are correct, if both stepper motors are powered at the same time, you'd be at the max output of the 3A buck converter.

4) This is part (sort of) wiring diagram, part flow diagram. Pick one and stick with it. If it's a wiring diagram, keep + and - separate, including at device inputs and outputs.

-B.

 

I agree with Werecow, you need to put the driver outputs into high impedance mode then disconnect the motor leads from the driver completely before connecting them to your crossover switch circuit. How do you control the speed of the motor without the driver? It would seem to be just full speed ahead!

As for the stepper motors, I'd remove all the existing hardware and use a pair of TMC2209 drivers, using the full 24 volts to supply them and limiting the currents accordingly. No need for the buck converters or reverse voltage protector!

 

Post #4 sort of describes the desired functions, sort of. The drawing tends to confuse things.
A more detailed description of the desired results, along with the chosen modules, would be close to an adequate description. Whatwe have is not.

 

As already mentioned, the drawing only shows power connections, and those are wrong.Not one bit of control connection. Itis not even an adequate flow chart!!

Hi,

Oh I did not check it for working or not working I just noticed that it needed to be cleaned up so that it appears on a monitor without all those extra lines. The image needed "descreening" and I don't have that built into my filter set yet, so I used a very simple descreening method. It works but it's not the best by any measure.