- #1
William123
- 39
- 0
Hi
I'm working on a project in school (or at home) about brushed DC motors. I have recently built a prototype myself but instead of using permanent magnets around the armature I'm using an electromagnet from another motor that died. I intend to build another motor using the same armature but this time with permanent (neodymium) magnets and I'm going to measure the RPM of the two motors when they draw the same amount of current. What are your predictions? I read somewhere on the internet once that voltage determines the speed (this is probably not the whole truth) and according to this statement the first prototype should run much faster because the resistance is higher in that motor, which means higher voltage to reach the same amp draw. This doesn't really make sense to me though, I feel like they should reach about the same RPM.
I also noticed that the back emf generated by this first prototype wasn't all that much. It was noticeable but I'd like to see a bigger difference in the current draw when the motor is running vs when it is stalled. At 40-45V the amp draw was 1.8 when stalled and 1.6 when running maybe (i can double check this later). Does this have anything to do with the fact that I'm not using permanent magnets or is it all based on the friction inside the motor?
Thanks in advance :)
I'm working on a project in school (or at home) about brushed DC motors. I have recently built a prototype myself but instead of using permanent magnets around the armature I'm using an electromagnet from another motor that died. I intend to build another motor using the same armature but this time with permanent (neodymium) magnets and I'm going to measure the RPM of the two motors when they draw the same amount of current. What are your predictions? I read somewhere on the internet once that voltage determines the speed (this is probably not the whole truth) and according to this statement the first prototype should run much faster because the resistance is higher in that motor, which means higher voltage to reach the same amp draw. This doesn't really make sense to me though, I feel like they should reach about the same RPM.
I also noticed that the back emf generated by this first prototype wasn't all that much. It was noticeable but I'd like to see a bigger difference in the current draw when the motor is running vs when it is stalled. At 40-45V the amp draw was 1.8 when stalled and 1.6 when running maybe (i can double check this later). Does this have anything to do with the fact that I'm not using permanent magnets or is it all based on the friction inside the motor?
Thanks in advance :)