Constant power circuit idea for driving motors

Hi all,

Forums member @VitalSparks has been talking with me about an idea he has for his upcoming scanner design. He is going to try using the concept of “constant power” to drive his motors. I did not know what that is and he was kind and patient enough to walk me through it over a series of texts and phone calls.

I’ve made a video that outlines the idea and how it might apply to Kinograph: - YouTube


Know anyone who could help us prototype this circuit? I’m out of my depth.

Here are some other links/resources that might be useful for further digging:

StackExchange Thread
Possible chip for accomplishing this
YouTube video on varying load with practical application
Datasheet for a motor that might be good for this:

Jeff’s notes to me regarding the actual circuit design:

Basic system diagram:

basic_system_map.pdf (53.4 KB)

the video is listed as “private” so it can’t be viewed. Can you check the permissions?

Done! It should be viewable by anyone now.

@matthewepler motors are not my strong side, so was trying to follow your discussion. This video maybe also be helpful.
It is a bit late and my “fried is brain”. I could not wrap my head on a reel with very little film and a reel almost full, requiring the same power to spin. And the power to charge/discharge the inductor would change depending on the speed, and with little film more speed, more film slower speed (I think).

Thanks for the helpful link @PM490. I’ll take a look as soon as I un-fry my brain after a weekend with a 4 year-old nephew :slight_smile: