Re: How to make a cheap and effective inductive ballast

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

This surprises me greatly that magnetic forces between
these coils could manifest themselves without an iron
core?"

   Try it and be surprised!  You don't need the core to get magnetic forces.

    There's a very easy way to measure the mutual REACTANCE.  Pass 
an AC CURRENT of say 1 amp through one coil and measure the voltage 
across the other.  The mutual reactance is the ratio of that voltage 
to the current in the other coil..  Divide the reactance by [2 pi f], 
where f is the line frequency.  Say that the voltage for 1 amp is 
0.377 volts.
Divide that by 1 and the reactance is 0.377 ohms.  Divide that by [2 
pi 60] (=377) and you get 0.001 henry or 1 mH.  Use a 100 watt light 
bulb in series with the coil to make things easy.  The current will 
be about 0.8 amps.  Use an AC ammeter if you have it and get a closer value.

Ed