Calculating speed using a bicycle dynamo.

azrael

·I am building a toy which measures the speed and it will display the data in the LCD screen.

·To measure the speed i am uisng a bicycle dynamo.

·By using the following data:

·Kinetic Energy = 1/2 mv^2··· and··· Dynamo energy= Power*time,·········· m can be set any any constant value, etc=10kg

·I have come up with the following formula to find speed:

·v = sqrt ( 2*power*time/Energy)

·The dynamo is rated at 6v 3W.

·I understand that the dynamo produces an analog voltage, and this might be converted using the command "rc time".

·Can anybody help me with the programming code incorperating the formulas and factors above.

·I am lost at the moment.

·Aaron

stamptrol

Aaron,

Your dynamo will be one of two types: DC or AC. You can check the nameplate or check the output waveform.

If it is DC, the voltage will vary with speed and you can measure that with an analog to digital converter chip. Or, feed the voltage into a small incandescant lightbulb and sense the brightness with a light-dependent photocell. This method can be used with RCTIME.

If it is AC, the frequency will vary with speed. You can use the PULSIN or COUNT command to see the change as speed changes.

Be careful in connecting to your Stamp pins as the voltage can be much higher than 5 volts when the dynamo is not loaded!

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Tom Sisk

http://www.siskconsult.com
·

El Paisa

Seems to me that you need categorize the generator.

Your theorical approach is fine but in addition to that you have to incorporate the generator parameters.