- Greetings -
Scott asks a valid question regarding diodes. My comments on having about
50% of the diode polarity marks pointing to the lamps from the hot side
and 50% pointing the other way assumed that small diodes are being used,
one per lamp. No, I do not envision two or more diodes in series for any
lamp or collection of lamps.
Thanks to Chuck for his comments on the soft turn-on and off which half-
wave rectification gives to lamps. A friend, formerly with GE Outdoor
Lighting, told me this method of reducing lamp brightness yielded longer
lamp life than switching the voltage on at high voltage parts of the cycle
such as lamp dimmers do.
Thanks also to Chuck for his comments regarding "built to the buck" TV
sets (which includes most all of them). The fine print, probably on the
back of the set somewhere speaks to FCC regulation (part 15?) that the
TV will not interfere with other devices and, continuing, other devices
may interfere with it. The plastic cabinet is good for meeting electrical
safety requirements of UL, but does nothing with regard to keeping inter-
ference radiated by other devices including AF #282 out of its sensitive
circuits.
Most series motors around the home today have interference-suppression
capacitors connected in parallel with the brush holders. I have seen this
in line-powered electric razors and electric food mixers. In the matter
of experimenting to reduce AF loco interference, a 0.1 uF capacitor has
about 25 kilohms reactance at 60 Hz. At 25 VAC across the armature (more
than the AF transformer provides), the cap will draw only 1 mA. However
it's reactance drops inversely with frequency which diminishes the inter-
ference currents outside the loco. A similar cap between the tender or
Diesel trucks will help some more. Maybe one cap every 10 feet of track
will help. Therein lies the experimentation.
I have not seen capacitors applied between the commutator segments on the
armature. I suspect that the voltage stored on the cap when the second
segment turns under the brush results in capacitive discharge currents
thru the brush surface (one segment to the next) causes more harm than
good. My close experience is limited to motors from the Norelco razor
size to 21 HP, 120 V, approx 150 A series motors. If you know of one
having a string of capacitors between segments, please tell me about it.
Have fun controlling the noise.
CheerS.
Rhett - KE4HIH
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