[ARC5] Halogen Light Power Supplies

[john rose]

Among my collection of slide rules is a Mazda Lamp Characteristics Calculator from GE, Nela Park (Cleveland) Engineering that ‘instantly’ calculates several criteria.

If you have a bulb rated for 115 volts and apply 105 volts;

you reduce the wattage used by 13%

you reduce the light output by 26%

you increase the life expectancy by 260%

you increase the unit cost of light produced by 113%

Therefore, to get that long life you waste 13% (light output down 26% yet the wattage is down only 13%) of your dollar spent to Edison. Over the expected lifespan of 2.6 times ‘normal’ you will fork over 34 percent more money than using rated voltage (260 x 113= 294 total cost vs 260 =34%). 

Aren’t tekgnawlogy wunnerfull?



From: Roy Morgan
Sent: ‎Monday‎, ‎May‎ ‎4‎, ‎2015 ‎7‎:‎57‎ ‎AM
To: Dennis Monticelli
Cc: arc5, Robert Eleazer






On May 4, 2015, at 4:13 AM, Dennis Monticelli <dennis.monticelli at gmail.com> wrote:

> Bill,
> 
> I have one of those ancient lamps too.  Just put a resistor in series to
> limit the current.  I run mine well below line voltage to insure its
> survival.  When under-driven the light is orange and rather dim but I still
> get a kick out of it.

Same here.  Running such  light bulb at say 100 volts or a bit less will let it last nearly forever.  There is technical information about the effect of lamp voltage on expected life - it’s a ten to the 6th power curve or some such.  The bottom line is that running a 120 volt lamp on 105 volts will let it run for a VERY long time.

The longest burning light bulb is at a fire house in Livermore, CA, and is much celebrated:

http://www.centennialbulb.org/

Happy glowing!

Roy

Roy Morgan
k1lky68 at gmail.com
K1LKY Since 1958

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