On 11/12/2011 1:20 PM, Howard Lester wrote:
> I bought a screw-into-an-outdoor-light-socket photocell in which you then
> screw in a lightbulb. The photocell, of course, would keep the light off
> during the day, on at night (or maybe during a total solar eclipse, too).
> But the one I bought at Lowe's (I didn't note the brand) put out tremendous
> nighttime RFI, at least on AM Broadcast, and that is entirely unacceptable.
> Do any of you know of a good brand of these things?
That's unlikely. :( You MIGHT be able to kill the RFI with your
installation by one or both of the following:
1) A suitable capacitor ACROSS the line -- that is, between Line (Hot)
and Neutral (White). To be safe, this must be a cap rated for the high
voltage spikes that often occur on the power line (3-6kV). This requires
a cap with an X2 rating. I would choose a value on the order of 0.05uF
(50 nF). The leads should be VERY short. The capacitor should be right
at the noise source, on the line side.
2) A suitable common mode choke, formed by winding all three of the
power conductors for at least ten turns through a #31 ferrite toroid, or
5-7 turns through .one of the "biggest #31 clamp-ons" (1-in i.d., about
1.5 inches long) listed in Appendix One of my RFI tutorial. The choke
should be very close to the offending fixture.
I would try the capacitor first, both because it's the mostly likely
fix, and because it's the easiest and lowest cost.
73, Jim Brown K9YC
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