DC motor interference

[woodturner550]

I am powering a small laser and a small DC motor from the same power source (3 volt). How do I make sure that there is not a signal coming from the DC motor to the laser? Do I need a capacitor to filter this across the positive and negitive leads going to the laser?

When we photograph the laser output we don't want signals or interference showing up. We could use two power sources if needed.

Thanks

woodturner550

 

[Reloadron]

The ideal situation would be to use independent power supplies. Next give this a read. You really want to get interference at the source and that is the motor. You can experiment with .001 to .1 uF caps configured as shown in the link. That and some generic ferrite beads. Again, I would first use supplies independent of each other.

Ron

 

[woodturner550]

Thanks Ron,

I figured a cap but had completely missed the ferrite beads. The text is a great example of how to solve the problem I was concerned with happening. Some of the hobbist working on lasers have had a problem with what they call "microwave interference" on the final product. I believe that the "microwave interference" is simple noise. In a few weeks I will know.

That said the question I come up with is if I use two power sources will I still be getting noise from anything on the power grid? OR will using two sources for power even if from the same "wall plug" solve the problem? What I am working on is a 3D laser scaner that converts from object, to scan, to 3D model, to output for CNC machine.

I am glad for you and the forum at large, one for not making those of us with questions feel like fools for asking, second for the great volume of knowledge and experience that can be tapped into.



Thanks again.

woodturner550

 

[Reloadron]

That said the question I come up with is if I use two power sources will I still be getting noise from anything on the power grid? OR will using two sources for power even if from the same "wall plug" solve the problem?

Good power supplies are designed not to feed noise back into the mains. I don't see it as a problem. Generally if you notice the people into various robotics make it a point to remove motor noise especially when working with uC chips. Keeping the motor on one power supply and the sensitive electronics on another is a good way to go. However I would try a little filtering first. This is also where a scope is a good tool to have but lacking a scope I would filter the motor and see what happens.

I agree these forums are a wealth of great information and the people here are always willing to help.

Ron