[RFI] 120v halogen lights

Martin Ewing martin at aa6e.net
Sun Apr 4 13:58:38 EDT 2004

OK, I've heard this said before.  But inquiring minds want to know:  why 
should DC be worse than AC for lifetime in lighting applications?

I seem to recall it was an issue for vacuum tube filaments, presumably 
because having a DC gradient on the filament led to unequal 
concentration of emission on the filament.  (On the other hand, AC 
supplies could lead to hum.) But in a lighting situation?

I can think of a couple reasons why DC might be better: no AC-induced 
vibration, unity peak to average power, etc.

73 - Martin, AA6E

> Subject:
> Re: [RFI] 120v halogen lights
> From:
> "Tom Rauch" <w8ji at contesting.com>
> Date:
> Sun, 4 Apr 2004 10:23:22 -0400
> To:
> <rfi at contesting.com>, "Pete Smith" <n4zr at contesting.com>
>>I assume that there is no reason why any real transformer that delivers 
>>12.6vac couldn't be used -- perhaps even an AC wall wart.
>That's right, as long as it is AC. If you run DC bulb life is shorter.
>73 Tom 

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