> Amplifiers and other devices with capacitor input power
> supplies have terrible power factors. The stiffer the
> power
> supply (the better the PS construction) the worse the
> power
> factor becomes.
By the way, I'm not agreeing or disagreeing with the use of
number 12 wire to power a TL-922.
It's just very important for people to understand the
following with capacitor input supplies:
1.) The better the transformer and power supply is
constructed, the worse the power factor becomes. This means
the peak current will be higher and voltage regulation more
dependent on oversizing the power mains wiring as the power
supply quality is improved.
2.) We cannot measure voltage drop on a power line using a
traditional meter. This is because RMS voltage is affected
very little by the peak clipping caused by power supply
loading. The metering has to be a peak detecting system
without averaging.
The end effect is the power mains resistance tends to
equalize performance between good and bad supplies, making
what could be an exceptionally stiff supply loose because of
power mains resistance. It's always a good idea to oversize
the wiring as much as possible when running a high power
factor load, and we absolutely cannot rely on the "heating"
rating of wiring to determine the best size for high power
factor loads like capacitor input supplies. We also cannot
judge the regulation by monitoring the line with a normal AC
voltmeter.
73 Tom
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