Hi Everyone,

I am extremely green to the electronics world, and as such I am looking for direction on a new project.

I need to drive a DC motor clockwise 45 degrees, then counterclockwise 45 degrees repeatedly for a period of approximately 3 seconds, then dwell for 3 seconds, then repeat. I'd like to use a 6 or 9V power supply and the motor run sequence should simply be controlled by an on/off switch. Motor speed must run at approximately 200RPM.

What would be the simplest/cheapest method for controlling this motion sequence?

Are there any concerns regarding motor longevity?

 

The first part of your requirement is pretty easy, just use a RC servo motor. But the second part the RPM requirement makes no sense. What exactly does a 200 RPM have to do with moving 45 degrees?

Link to RC servo understanding; http://www-cdr.stanford.edu/dynamic/servo/

 

You may be better off with a stepper motor, a typical application.
Max.

 

What are you trying to do ????
Is this a Top-Secret Military Project ????
Sounds like you need a Windshield Wiper Motor.

 

What exactly does a 200 RPM have to do with moving 45 degrees?

It means that 45 degrees takes 37.5ms. So how can it take 3 seconds? Unless you mean a 200 rpm motor with a 80:1 gearbox?

You may be better off with a stepper motor

Or you'd need a pair of limit switches.

 

It means that 45 degrees takes 37.5ms. So how can it take 3 seconds? Unless you mean a 200 rpm motor with a 80:1 gearbox?

The requirement wasn't mine but was the thread starters, who seems to be missing in action.

 

The requirement wasn't mine but was the thread starters, who seems to be missing in action.

Apologies. Although I knew that I should have written “unless the TS means. . . “

 

I'm looking to cycle the motor back and forth for a duration of 3 seconds. Assuming the motor starts at a position I'll call 0°, one cycle constitutes travel CW to +45°, then CCW to -45° (90° of travel), then CW back to 0° (45° of travel) for a cumulative angular motion of 180°. At a rotational speed of 200rpm, assuming no delays between CW/CCW motion, with 3 seconds of cycling, the motor will perform "one cycle" of cumulative 180° motion 20 times.

Sounds like a RC servo motor would be a reasonable fit for this application?

 

Sounds like a RC servo motor would be a reasonable fit for this application?

It depend on how long you want it to keep doing this. A RC servo motor has a run time before failure of 500 hours.

A 1.8 degree stepper motor doing 25 steps forward and 25 steps back could run (almost) for ever.

 

At a rotational speed of 200rpm, assuming no delays between CW/CCW motion,

Again why is the 200RPM so important? Maybe telling us what you are moving will get better answers.

Sounds like a RC servo motor would be a reasonable fit for this application?

What I said in my first post.

 

For that small of a movement and speed, you most likely could get away without a sophisticated stepper drive, just a switching device transistor/Mosfet using a fixed plate voltage of the motor.
At the desired No. of step counts.
Max.

 

Here is using the cheap L298 board, with Bipolar stepper motor.
Max.

 

It could also be done mechanically, like the mechanism used in most shapers back in the day. Look in this link to how it was done; https://technologystudent.com/cams/crank2.htm