Feedback motor with PCv3.5 and R/G/RB tri cree question

[RobotCamel]

I'm working on a saber that will use a PCv3.5 and have an R/G/RB Tri Cree to do a color changing blade, and I am thinking of adding a feedback motor.

The specs for the motor are 3V - 75mA.

I was originally just going to have the on-board driver run the red die (2.65v @ 1000mA). But in doing the math based on the PC manual for the motor I would get this:

R = (Vled - Vmotor) / current
R = (2.65v - 3v) / 0.075mA

This clearly wouldn't work because there's not enough voltage, right?

So, I assume, I can just make the green die (3.7v @ 1000mA) use the on-board driver, since I can select the die configuration in RICE (GRB instead of RGB). This way I should have enough voltage for the motor:

R = (3.7v - 3v) / 0.075mA
R = 9.3 Ohms or round to 10

I don't know a ton about electronics, so I'm just wondering if I can get some expert insight.

Also, I'm curious how the motor would work when it comes to a color changing blade, since the current could change depending on what color the blade is. Like, for example, if the color I'm using doesn't have any green in it, then the motor wouldn't even work right?

Finally, I think I've seen in another post that I can just add a switch in series with the motor to have the ability to manually turn the motor off if I want. Is that correct?

Thank you very much for your time. I really appreciate any help.

[Silver Serpent]

Eh, it's a motor. It'll run with a lot less voltage than the specs state. It'll just run *slower* is all. The calculations for vibration motors are there to give you a starting point for figuring out a resistor. You'll nearly always want to tweak it to slow the motor down some more, as a vibration motor running full tilt would quickly get annoying in your hand.

With a color changing blade, you are correct. If the color that the motor is linked to is off, then the motor is not going to be running.

A latching switch in series with just the motor will give you a kill switch for the motor, and it won't hurt or affect anything else.

[Taki117]

As a side note, I'm fairly certain that feedback.motors are covered in the PC manual. Give that a read.

[RobotCamel]

Thank you for the clarification Mr. Serpent.

And actually, Taki117, I had already read the manual and was just looking for some information that was unclear to me based on reading that. But thank you for the heads up.