D
Doug Goncz
- Jan 1, 1970
- 0
Hello!
From down under, with stamps all over it, comes a package from Oatley
Electronics containing four 1 watt white LEDs and four lenses. Each LED is
about the usual size but is heat sinked to a disc about the size of an American
nickel. Quite heavy.
Each is rated 3.6 VDC, and a whopping 350 milliamps. I have a 15 V regulator on
my bicycle. Let's see, that's 2 x 7.2 or 14.4 volts for the LEDs off of 15 from
the regulator.
What are the efficiency tradeoffs between a resistor and a constant current
source? Is it better to use a constant current incandescent lamp as a source in
this application, or a semiconductor solution? I suppose the semiconductor
would be more efficient but the lossy lamp gives some light which counts toward
efficiency.
I calculate a 43 ohm, 6 watt resistor. Did I get it right?
What's the most efficient setup for these LEDs in series or even parallel, with
the given source, 15 V, capable of 5A. (It also runs an inverter)? Do I need to
evaluate the performance of the regulator at 350 milliamps?
My intuition is that these 4W of LED lighting should be the equivalent of 16W
of incandescent, assuming they do about as well as fluorescents. With the
lenses, I should have plenty of light forward with a mere twitch of the pedals.
Is the right resistor calculation 0.6 V / 0.35 A = 1.7 ohms, 1/4 watt? That is
acceptable on efficiency.
Should I further heat sink the 4 LEDs side by side on a 1/8 or 1/16 inch thick
aluminum base about 6x1 inches, forming a chassis with more structure
supporting the lenses and enclosing the system?
My physics project at NVCC:
Google Groups, then "dgoncz" and some of:
ultracapacitor bicycle fluorescent flywheel inverter
From down under, with stamps all over it, comes a package from Oatley
Electronics containing four 1 watt white LEDs and four lenses. Each LED is
about the usual size but is heat sinked to a disc about the size of an American
nickel. Quite heavy.
Each is rated 3.6 VDC, and a whopping 350 milliamps. I have a 15 V regulator on
my bicycle. Let's see, that's 2 x 7.2 or 14.4 volts for the LEDs off of 15 from
the regulator.
What are the efficiency tradeoffs between a resistor and a constant current
source? Is it better to use a constant current incandescent lamp as a source in
this application, or a semiconductor solution? I suppose the semiconductor
would be more efficient but the lossy lamp gives some light which counts toward
efficiency.
I calculate a 43 ohm, 6 watt resistor. Did I get it right?
What's the most efficient setup for these LEDs in series or even parallel, with
the given source, 15 V, capable of 5A. (It also runs an inverter)? Do I need to
evaluate the performance of the regulator at 350 milliamps?
My intuition is that these 4W of LED lighting should be the equivalent of 16W
of incandescent, assuming they do about as well as fluorescents. With the
lenses, I should have plenty of light forward with a mere twitch of the pedals.
Is the right resistor calculation 0.6 V / 0.35 A = 1.7 ohms, 1/4 watt? That is
acceptable on efficiency.
Should I further heat sink the 4 LEDs side by side on a 1/8 or 1/16 inch thick
aluminum base about 6x1 inches, forming a chassis with more structure
supporting the lenses and enclosing the system?
My physics project at NVCC:
Google Groups, then "dgoncz" and some of:
ultracapacitor bicycle fluorescent flywheel inverter