You might be able to spread the beam out by grinding/polishing a flat
spot on the end to counteract some of the focusing effect.

Larry A.

Alistair Bell wrote:
>
> I was inspired by the German site and by Roger's work so yesterday at work
> while waiting for some E. coli to grow, I tried my hand a making a LED dash
> light.
>
> materials:
>
> red LED from bike light. Unsoldered from little board, which of course meant
> it only had very short "legs". Checked out to be approx. 1.8 V and a narrow
> beam spread (20 degrees?). "Flattened" area at base of LED indicates the
> negative post.
>
> resistor - 470 - 500 ohm (calculation/estimation based on a dash voltage of
> 10V and a LED voltage of 1.8)
>
> dash light bulb holder.
>
> some 22 gauge telfon insulated tinned copper wire (scraps at hand)
>
> heat shrink tubing.
>
> Method (made up as I went along):
>
> drilled 1/16" hole in base of bulb holder. Soldered 1" lengths of wire to
> the legs of the LED. shrunk small lengths of heat shrink over the solder
> joints. Cut one of the lengths of wire back to aprox 1/4" and removed
> insulation. Tinned/soldered the exposed wire to make solid. Bent that back
> upon itself to make a tight "V".
>
> The other wire is fed down through the bulb holder and out the drilled hole,
> The LED is pressed into the holder with the bent wire making contact with
> one of the internal bulb holder contact. The LED is a good fit and the bulb
> holder itself "stretches" a little to hold it in tight. I marked with a felt
> pen the side of the bulb holder that the LED was making contact with the
> internal contacts.
>
> The wire sticking out of the base was trimmed a little and leg (trimmed
> also) of the resistor soldered to it. A very short length of wire was
> soldered to the other leg of the resistor.
>
> The free end of the short length of wire was soldered to the "topside" ie
> the side that does not come in contact with the circuit foil. This is a
> tricky part, you'll see how to solder it when/if you do it!
>
> A bit of heat shrink over the resistor and wires and its done!
>
> One has a 50% percent chance of getting it right when you twist it into the
> circuit foil, I don't know if these LEDs "pop" if full voltage is applied
> "backwards" so I inserted into foil with dash light rheostat turned way
> down.
>
> Well it works, but as Roger found too, the beam is quite narrow and only
> illuminates the top half of the gauge. The little reflector assembly might
> be modified (foil inside?) but better to have a wider beam spread LED.
>
> Inserted into the centre position, that is the bulb that lights up the idiot
> lights, the LED illuminates all of the icons but not evenly.
>
> The LED does dim with the rheostat, but does not go out at the
> lowest/dimmest setting.
>
> But I think it was a worthwhile exercise, now I'll go get a range of LEDs
> and experiment further.
>
> Alistair
>
> --
> '82 Westy -> diesel converted to gas in '94
> albell@uvic.ca
> http://members.shaw.ca/albell