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soyuppy wrote:Does anyone know what the max V that the CD motor can produce? Is there a way to find out from spec? Would different manufacture have different V output? Is there different between CD motor vs DVD motor (portable DVD player)?

I am a novice at this as well, but this is what i found. CD players at a slow speed do not produce more that 0.1V which is hard to measure and not very predictable. I found a toy motor that needed a lot more energy to turn the object it was hooked up to. With this motor, when you turn it at slower speeds you get a much larger voltage (close to 1 volt at slow speeds) but the drag is greater.
I am not an expert on this so I may be completely wrong. Please let me know if you agree or disagree with me on this.

can you use any materials for the fan?

The rules state that the ES must provide: 2.d.ii - "Support stand(s) that allow for vertical and horizontal adjustments of the blade assembly."

Can this be interpreted to mean that blades can be created in a way so that when the cd is attached, the cd face is parallel to the testing table that the stand rests on?

Or.. Do all blade assemblies have to be tested with the CD face perpendicular to the testing table. ___ or I ?

Thank you.

rschmitz wrote:Can anyone tell me how to find a load resistor for the testing apparatus? not sure why this is needed.
Also, my motor that I have has capacitors on it. should I remove them?

No need to remove the capacitors. For resistors, you can try Radio Shack is there is one of the few still in existence near you. Otherwise I'd recommend Digikey.com or Mouser.com

The reason for the resistor is we want to measure power. Power = Voltage * Current. Without the resistor in place, all the current is trying to go through the multimeter, which has a VERY high resistance, and hence will cause very low current flows = inconsistent readings on the multimeter. Putting a small resistor in the circuit give the current a better path to flow through, and hence more consistent readings.

Error_v2 wrote:can you use any materials for the fan?

Anything non-metallic can be used.
Also, if you use a third-party kit, you must include one functional change in the design.

The rules state that a standard, 12cm diameter CD is used. On the diagram of the stand, however, it shows that the radius of the CD on the mount is 3cm. Is that a mistake, or am I just reading it wrong? Thanks!

GoofyFoofer wrote:The rules state that a standard, 12cm diameter CD is used. On the diagram of the stand, however, it shows that the radius of the CD on the mount is 3cm. Is that a mistake, or am I just reading it wrong? Thanks!

In the example diagram, the CD mount hub has a radius of 3 cm. The CD isn't shown in the diagram.

rschmitz wrote:

soyuppy wrote:Does anyone know what the max V that the CD motor can produce? Is there a way to find out from spec? Would different manufacture have different V output? Is there different between CD motor vs DVD motor (portable DVD player)?

I am a novice at this as well, but this is what i found. CD players at a slow speed do not produce more that 0.1V which is hard to measure and not very predictable. I found a toy motor that needed a lot more energy to turn the object it was hooked up to. With this motor, when you turn it at slower speeds you get a much larger voltage (close to 1 volt at slow speeds) but the drag is greater.
I am not an expert on this so I may be completely wrong. Please let me know if you agree or disagree with me on this.

not sure why bother trying on something other than CD motor. It doesn't matter how blade perform on toy motor, ultimately, you have to test the blade on CD motor.

is it possible that CD motor can get busted due to constant and repeated rotation both clockwise and counterclockwise? With load in the system, I'm seeing voltage reading all over the place. It drop as the blade spin faster.

soyuppy wrote:is it possible that CD motor can get busted due to constant and repeated rotation both clockwise and counterclockwise? With load in the system, I'm seeing voltage reading all over the place. It drop as the blade spin faster.

Do you have a resistor in the circuit as specified in the rules? Wild voltage readings is one indication that you might not have one.