--- In SkunkworksAMA_at_yahoogroups.com, "Terry" <tpuffies_at_h...> wrote:
>
> 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.
If you want low resistance, use thick speaker wire for your power
leads. They are designed for long term loads with low resistance for
better sound. And remember, the load creates heat in the wire and
heat increases resistance. And always use paired wires, since the
flow of electricity also induces magnetic fields and the paired wires
cancel each others fields.
I hope that made some sense...
>
> 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.
Isn't it nice that Radio Shack still sells parts...
> 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.
You can buy clear dust goggles at most hardware stores. If you remove
the entire lense you could drill 2 holes, one over each eye, for the
LED aray and simply move the aray from one opening to the other.
If you secure the cable at temple so that it travels over the ear
before dropping, it would keep it from pulling the goggles ascue while
sitting or laying down. No matter how balanced or secure the cable,
this is not something to wear while walking around the house...
This link shows the style of goggles I'm refering to:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=35710
Received on Tue Mar 09 2004 - 23:25:25 CST