Date: Fri, 6 Dec 2002 13:46:03 -0800
Reply-To: fortinoj@SPEAKEASY.NET
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Joseph Fortino <fortinoj@SPEAKEASY.NET>
Subject: Re: Blue LED instrument lighting
Content-Type: text/plain
screen shot? what a write up
On 06 Dec 2002, 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
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