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electromagnetic controls

Greetings Folks New to these groups here, and have not checked out any of the archives yet, so please forgive the simple question if the obvious is already out there waiting for me... : ) I would like to scratch build one of those electromagnetic devices that will float things under it. Maybe a steel ball bearing. While I have an idea of the whats and whyfores, no reason to reinvent the wheel if one of you already have the plans... I've never seen one, but would it be possible to do this in reverse, I mean like having the ball floating above the surface of the device??? I've been daydreaming of making a miniture solor system with various steel balls sitting on the glass of a smooth running clock that would act like those skaters on the glass ice rink music boxes. Anyone know how I could speed up one of those clocks??? I've been looking for a DC that runs smooth rather then the harsh clicking per second, and know they are out there, but not at the cheap stores that I've been haunting for the goodies... Any hints on these subjects would be appreciated. Thanks in advance Bill

Reply to
ke9xq
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The floating-ball gadget needs a feedback loop containing the magnet, something to sense the position of the floating ball, and an amplifier to drive the magnet. The sensor I remember from the days of Popular Electronics was a photocell and lamp, set up so that the position of the ball varied the amount of light reaching the cell.

The usual battery-powered clock has an oscillator, usually a quartz crystal digitally divided down to 1 Hz, driving a stepping motor. The stepper is used because it doesn't need much power, and because people still expect clocks to 'tick'. Line powered analog clocks have synchronous motors running at 3600 RPM (on my side of the Atlantic), geared down to 1 RPM for the second hand, which gives very smooth motion. You can get these motors with various gear ratios from the big supply houses. If you need to run the system from DC, you could drive the motor with an inverter locked to a precision frequency reference. Clock motors draw less than five watts, so the inverter could be just an audio amplifier and a transformer, driven by whatever precise 60-Hz source you can come up with. I vaguely remember an article by an amateur astronomer who built such a device to drive his telescope. Another approach would be to control the speed of a high-speed DC motor that has some kind of magnetic or optical pulse generator on its shaft. Compare the pulse rate from the shaft with a quartz-crystal reference (after suitable processing to match the frequencies), then use the difference to vary the voltage supplied to the motor. That looks like more trouble than coming up with

5W at 60 Hz to drive an off-the-shelf synchronous motor.
Reply to
Stephen J. Rush

snipped-for-privacy@charter.net sez:

Google "maglev" OR "magnetic levitation". One of the resulting hits took me here:

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Look in the left margin under "Levitation".

Reply to
Esther & Fester Bestertester

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