Robert Clark wrote:
http://64.233.161.104/search?q=cache:Su6AOXBIC9EJ:
On this Powerlabs.org page I saw discussed use of a Dremel grinding tool to generate high revolutions per second:
PowerLabs High Speed CD-Rom Experiments.
This tool can generate 35,000 RPM or nearly 600 revolutions per second. Perhaps this can be used to increase the current generated by an electrostatic generator by increasing the rotation speed. See the formula on de Queiroz's page for the current generated:
Maximum electric field.
De Queiroz gives an example here of a rotor with 13 cm, 5", outer diameter with a rotation speed of 40 revolutions per second generating
36 microamps. So at 600 turns/sec using the formula there should be 15 times the current or 540 microamps. Note too that in the example there is a 9 cm inner diameter which reduces the surface area by about 1/2. So for a solid disk at 13 cm diameter there would be about 1000 microamps, 1 milliamp. Dremel grinding tools are available for reasonably low prices. Here's one for $29.00 US:Wholesale Dremel Type Rotary Electric Grinder kit NEW.
You could also increase the current by increasing the number of rotors (but see the caution below.) Note that the idea is to see if these electrostatic generators could provide a self-contained power unit for a lifter. But at first we want to see if they can supply sufficient power/current to raise just the lifter. So in the first experiments you just use already existing electrostatic generators on the ground, which are not optimized to be lightweight. Then we also want to see how the energy of rotation is stored and converted into electrostatic energy. So once it is confirmed the generators can provide sufficient power, you disconnect the Dremel to see how long the rotor can spin fast enough to provide sufficient power to raise the lifter. Note that these first experiments are done in air so the air friction will significantly reduce the rotation time once the Dremel is disconnected. Later the idea would be to contain the rotor in vacuum. This will increase the rotation time and at the same time increase the voltage possible 30 to 50 times. (Note that to get this voltage increase, it has to be a very high vacuum since reducing the pressure can actually decrease the breakdown voltage until very high vacuum is reached.)
CAUTIONS! Note that on the Powerlabs page they were attempting to cause a CD disk to disintegrate by spinning at the highest speed of the Dremel. In
*this* experiment they had to additionally strike the spinning CD with another CD to get the spinning CD to shatter. But there have been cases where CD's have shattered at lower speeds than 35,000 RPM. Also after rotating at this speed for some time, the CD would suffer stress fatigue and would become even more likely to shatter. So even if you spin a rotor at a high speed for some time, at a later time it can still shatter at that very same speed. Acrylic if that is used for the rotor probably would have comparable tensile strength as a CD. It is *strongly* advised that the rotor be gradually brought up to higher speeds stepwise. And it is *strongly* advised that the rotor be behind a protective wall during these experiments. You can view the experiment by video camera or by mirrors (metal so as not to shatter.) In the Powerlabs experiments the experimenter held the Dremel with the spinning CD out in front of him. This is strongly disadvised. Note also if you use more than one rotor on a single Dremel this could cause wobbling which could put more stress on the rotors increasing the chance of shatter and also making the directions the shards would go more unpredictable. Also, if you increase the diameter of the rotors the speed at the edge of the rotor is also increased thereby increasing the chance of shattering. Moreover, the Dremels are actually designed for rather small diameter grinding attachments. Large diameter rotors could damage the Dremel motor.Bob Clark