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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Make your own Generator
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<blockquote data-quote="timetraveller" data-source="post: 108482" data-attributes="member: 456"><p>Perhaps I can throw some more dirt into the already muddied waters of this discussion. I have used stepper motors in two different telescope drive systems, one weighing 4.5 tonnes and one built in York in 1860 with a 15 foot long tube and a large amount of cast iron and bronze, with great success, but the electronics were done by specialists so what knowledge I have is peripheral to the fundamentals of these motors. First, for those who have no knowledge at all, a telescope has to be driven to follow the stars across the sky. The drive system should show no 'granularity' or otherwise any star images taken by photograph or CCDs will be widened by this 'granularity of the drive. Typically the stepper motors used had 200 steps per 360 degrees of rotation, which is much too coarse so they are used in what is called 'micro-stepping' mode wherein each step is divided into a further 64 micro steps. This will give a step size on the motor of 0.028125 degrees. Much too coarse, so then a further mechanical gear reduction of 1:100, or more, is required to get the less than one arc second of granularity required. What might be relevant in the present context is that one has to ramp up and ramp down the speed of movement, or the motor will stall. In addition one cannot try to get very high revs as the torque reduces to the extent that the motor will cease to rotate at all. Used as a motor, there are severe limits as to the speed at which these motors can rotate and still respond the their input pulses.</p><p></p><p>I am a great admirer of people who put their money where their mouths are. Had John Emmanuel and Dave Dunfey not put their time and effort in to fork modifications we would not have had the improved steering heads. So I am very pleased that people are now trying to find a way of using motors as generators. I hope I am wrong but I have doubts about stepper motors being able to generate significant power and I still have a niggle in the back of my head from school days about the phase of the windings and stators having to be different when the system is used as a motor or a generator. We will see.</p></blockquote><p></p>
[QUOTE="timetraveller, post: 108482, member: 456"] Perhaps I can throw some more dirt into the already muddied waters of this discussion. I have used stepper motors in two different telescope drive systems, one weighing 4.5 tonnes and one built in York in 1860 with a 15 foot long tube and a large amount of cast iron and bronze, with great success, but the electronics were done by specialists so what knowledge I have is peripheral to the fundamentals of these motors. First, for those who have no knowledge at all, a telescope has to be driven to follow the stars across the sky. The drive system should show no 'granularity' or otherwise any star images taken by photograph or CCDs will be widened by this 'granularity of the drive. Typically the stepper motors used had 200 steps per 360 degrees of rotation, which is much too coarse so they are used in what is called 'micro-stepping' mode wherein each step is divided into a further 64 micro steps. This will give a step size on the motor of 0.028125 degrees. Much too coarse, so then a further mechanical gear reduction of 1:100, or more, is required to get the less than one arc second of granularity required. What might be relevant in the present context is that one has to ramp up and ramp down the speed of movement, or the motor will stall. In addition one cannot try to get very high revs as the torque reduces to the extent that the motor will cease to rotate at all. Used as a motor, there are severe limits as to the speed at which these motors can rotate and still respond the their input pulses. I am a great admirer of people who put their money where their mouths are. Had John Emmanuel and Dave Dunfey not put their time and effort in to fork modifications we would not have had the improved steering heads. So I am very pleased that people are now trying to find a way of using motors as generators. I hope I am wrong but I have doubts about stepper motors being able to generate significant power and I still have a niggle in the back of my head from school days about the phase of the windings and stators having to be different when the system is used as a motor or a generator. We will see. [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Make your own Generator
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