Re: [Electronics_101] Re: I need some electrical advice for a Technics SA 404 receiver lighting
- Hello Steve,
At the bottom of the following web page there is Rapid Lamp Calculator
The diagram allows the user to determine the dependence of Current, Mean
Spherical Candela and Life on the value of voltage applied to the lamp
as a percentage of the design voltage for that lamp.
After looking at the diagram I come to the following conclusions.
1. Power dissipation is about 55% of the rated power when the light
output is 1/3 of the rated intensity.
2. The light output is approximately 10% of the rated intensity when
the power dissipation is 1/3 of the rated power.
3. My suggestion to operate the 80 ma and 250 ma lamps at approximately
equal power levels is a failure.
4. It is a good thing your were persistent.
5. Thankfully others have found some micro lamps with a rated output
close to the rating of the original 80 ma lamps.
The other Howard
On 4/27/2013 8:02 PM, raleigh_ranger wrote:
> Other Howard,
> > The odor may also be caused by the overheating of the fixture
> > the bulbs are mounted in.
> OK good point. If you are sure this is the case I agree.
> > Instead the power dissipated by 250 ma bulbs should be approximately
> > the same as the power dissipated by 80 ma bulbs. With approximately
> > equal power dissipated by both types of bulbs both types of bulbs
> >will produce approximately the same lumen output.
> This is the part I do not agree with.
> As someone else mentioned a 250mA filament will have more mass.
> If you dissipated the same power through a railroad spike it would not
> produce light. But a railroad spike will produce light if the amps are
> high enough. So what resistor would you put in series with a railroad
> spike to get the same light as a 80mA bulb?
[Non-text portions of this message have been removed]
- On 4/28/2013 2:10 PM, Bruzman@... wrote:
>Yes you would be safer going under spec.
> First off - THANK YOU to everyone for helping me out!
> Ok - I realize that a 70ma bulb will draw less current than an 80ma
> bulb. I located a bulb identical in size and shape to the original (8v
> / 80ma) but it is 8 v / 100ma.
> Would I be safer going under spec rather than a little over?
The other Howard
> The 250ma bulbs I tried had started to darken the pc board and I'm[Non-text portions of this message have been removed]
> glad I pulled them before the burned up. I don't know why I didn't
> think of the difference in amperage as causing more draw, more light
> and more heat - live and learn!
> I posted some pictures of my "project" thinking it might be easier to
> solve my problem.
> Again - THANKS for helping the newbie out! I loved electronics in High
> School and I guess I've got to re-teach myself things.