Magnetic induction question ---?
« on: October 01, 2005, 12:36:51 AM »
Some of you will figure out what this is really - - -

What would the waveform/voltage look like at terminals (1) & (2) with this wheel spinning at 1-3k?

There is a horseshoe magnet imbedded in the wheel.

There is only room for the wire on the side of the wheel to try to create a voltage - - -  Maybe I will have to eventually wind coils.

Anyone have a take on this?




Magnetic induction question ---?
« Reply #1 on: October 01, 2005, 03:34:03 AM »
> What would the waveform/voltage look like

I want to say "zero". The electrons may ripple but I don't see a net current flow.

Put your horseshoe on a record-player, put a wire near it, feed a DC-coupled 'scope. Only difference 3,000RPM makes is 100 times the voltage and frequency; a good scope will give enough of a small clue to tell you if this is remotely interesting or useless.

If you are trying to get POWER, not just signal, I think you need a much better layout.


Magnetic induction question ---?
« Reply #2 on: October 01, 2005, 06:48:23 AM »
..yep, to generate current, your magnetic field lines has to cross (repeatedly) the conductor - it's no use having the field moving in the same plane, as no crossing will occur..

And the voltage/current (when setup is changed) will depend on magnetic field strength, speed and density of crossing field lines, and wire dimensions

Jakob E.
..note to self: don't let Harman run your company..


Another clue-in
« Reply #3 on: October 01, 2005, 11:28:29 AM »
Here's how voltage is currently generated from this setup - to the tune of 10,000+ volts between (3) and (4). Powerful neodymium magnets + a stepup xformer.

I cannot tap this voltage, for it is very important for another purpose. There also is only probably 1/8 inch clearance between this wheel and its housing to try to eek any signal out.

I know this may seem like an odd question for this board, but I could think of no better people to ask than signal processing engineers!

P.S. Anyone know what this is yet? :green:

 :guinness:  :guinness:  :guinness:


Magnetic induction question ---?
« Reply #4 on: October 02, 2005, 02:10:13 AM »
> Anyone know what this is yet?

Lawnmower flywheel, of course. (But not B+S: the coil would be inside, right?)

And you want to power a car-radio on the handlebar.

Put a switch on the cam-shaft. The mag makes a pulse every turn, but you only need a spark every other turn (unless this is a 2-stroke). Grab the alternate pulses onto a big cap and 15V 50W Zener. That's almost how my BSA ran its lights.


Magnetic induction question ---?
« Reply #5 on: October 02, 2005, 02:26:12 AM »
Wait, there's an easier way.

The magnet and coil make a bi-polar double-pulse. The ignition is timed to use one side of the pulse; the other is just necessary to complete a cycle (there are no monopole magnets on the market). Put a rectifier and low-ohm high-watt resistor across the points. One way, the rectifier will sap ignition power, the engine will misfire at low RPM. The other way, the power is free (of course a load on the engine net power output and fuel consumption). The voltage across points tends to be in the range of 10V-100V, usable (unlike the 10KV side). The "right" polarity may not be right for your car-radio; float the chassis.


Magnetic induction question ---?
« Reply #6 on: October 02, 2005, 09:23:08 AM »
A little off topic.  Look at the power generating part


Motorbike Engine
« Reply #7 on: October 02, 2005, 02:29:03 PM »
Yes, this is a motorbike engine.

I'm going to try this - PRR; you should get your own statue somewhere for being a human encyclopedia.

First, I gotta replace the coil pack (transformer) because I notice that one side of it is de-lamming...

Thanks :thumb:


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