[GreenKeys] Why Dual Coil Electromagnets?

[Bob Camp]

Hi

I suspect the answer lies in the saturation of the cores.

Bob


On Jun 4, 2007, at 1:11 PM, Brooke Clarke wrote:

> Hi:
>
> I seems that for most of the 1800s in telegraphy, stock tickers,  
> district alarms, and clocks (probably in more places that I haven't  
> looked at yet) the electromagnet is formed by placing two coils  
> side by side and connected in series with the fields aiding.
>
> Do the early Teletype machines use dual coil electromagnets?
>
> It seems that more modern electromagnets are single coil.
> Are there any patents that point to why it was done with two coils  
> then?
> Maybe it relates to efficiency?  For example I have a Self Winding  
> "Western Union" clock that uses a pair of coils for the self  
> winding vibratory motor and another bigger pair of coils for the  
> hourly synchronizing electromagnet.  The winding motor runs from 3  
> volts (two 1.5 volt batteries).  It sounds like a small air  
> compressor that might be driven by a fractional horsepower motor,  
> yet the batteries are supposed to last a year.  I'll know in a  
> year, but for now think it must be a very efficient motor.
>
> http://www.prc68.com/I/SWCC.shtml
> -- 
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.precisionclock.com
>
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