Rather than glue the LEDs into a lens, I was thinking of making a
board with tabs to hang it from the frames. That way, it could be
moved from one side to the other, or put on different frames.
The wires thickness is a definate concern, but once you know the IR
drop across the supply wire, that amount figures into the
calculations for the current limiting resistors. For example, I found
some "monster cable" at the hardware store that is about 10 guage,
but VERY flexible. Perfect for what I want. The IR drop across 6 feet
of it at 10 amps is 0.18 volts. That gives me 4.71 volts at the card.
If I guesstimate .1 volts drop across the card, I base my resistor
calculations on 4.61 volts.
The LEDs draw 100 ma at 1.68 volts for the wide-angle 880 nm ones.
Which means that I need to figure a resistor that will drop the
remaining 1.45 volts at 100 ma. That means 12 ohms. Luckily, the
power dissipation in the resistor is less than the 1/4 watt rating of
the standard carbon-filled resistor.
For eyeglasses, the drop will be a whole lot less, since the number
of LEDs drops to about 1/6 as many.
I figure an 18 or 20 guage wire, clipped onto the top of the temple
pieces that go over the ear, will be fairly unobtrusive and even
serve to counter-balance the weight of the LEDs and card hanging on
the front of the glasses.
--- In SkunkworksAMA_at_yahoogroups.com, "Dragdamar Hsard"
<dragdamar_at_y...> wrote:
> I would think that it would be to flexable to be comfortable.
> However, a pair of generic safety goggles with the LEDs set in holes
> drilled thru the face would provide both comfort and a stable
platform
> for both the LEDs and the circuitry required. And the clear
> perforated sides would allow natural light in and fresh air to
> circulate. All you would need is a cord from your power supply to
the
> circuit board. However, the length of the cord would be limited by
> the amperage you are going to be pulling.
>
> I'm an electrician and have a bit of electronics training, so I do
> understand the constaints of voltage and amperage.
Received on Fri Mar 05 2004 - 09:21:28 CST