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Hi I am curious how the power levels are being implemented. I am not talking about the icon level navigation. How the motor actually adjusts to the different levels setting? Gear slipping? Thanks in advance... -- Elizabeth (20 years ago, 13-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | Re: power levels clarification
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(...) PWM - pulse width modulation of the electric current going to the motors. CS (20 years ago, 13-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | Re: power levels clarification
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(...) PWM--Pulse Width Modulation. Basically, during a cycle, power is turned on and off. The lengh of time the power is on is the pulse width. Longer pulse widths corispond to higher power levels. This cycling is supposed to happens fast enought (...) (20 years ago, 13-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | RE: power levels clarification
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Thank you very much for your clarification. Any suggestion on reading material about PMW for high school kids. -- Elizabeth -----Original Message----- From: news-gateway@lugnet.com [mailto:news-gateway...ugnet.com] On Behalf Of Thomas Johnson Sent: (...) (20 years ago, 13-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | Re: power levels clarification
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Hi Elizabeth, (...) there is an 8ms cycle, and the motor is on for a part of that: 1ms for power level 0, 2ms for power level 1, up to all the 8ms for power level 7. The rest of the time the motor is floating, i.e. the motor inputs are disconnected, (...) (20 years ago, 13-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | RE: power levels clarification
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This is really good info... Thank you very much... ---...--- -------- Best Regards, Elizabeth Mabrey Partner of Director LEGO MINDSTORMS 3322 Rt. 22 West, Bldg 4, Ste 402 Robotics Community Branchburg, NJ 08876 Ph: (908) 595-1010 ; M-F: 10-5; Sat: (...) (20 years ago, 13-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | Re: power levels clarification
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(...) Others have explained Pulse Width Modulation. However, if the kids are old enough to understand the difference between linear (straight line) and square law (curving ever upwards) and electrical voltage, resistance and power, you could say (...) (20 years ago, 13-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | Re: power levels clarification
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Hi Mark, (...) is it really true that there is a square law for PWM? Can you explain the reason why this is so? I understand that this is true if you change the voltage (half the voltage gives half the current so a quarter of the power). But I (...) (20 years ago, 14-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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| | Re: power levels clarification
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(...) I couldn't call myself an expert either! In your second way of looking at it, the full voltage and full current are already multiplied to give full power for part of the time. I=(Vcc-Eb)/R Current I, Voltage Vcc, Back EMF Eb and motor (...) (20 years ago, 14-Mar-05, to lugnet.robotics.rcx, lugnet.robotics.rcx.robolab)
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