Date:         Fri, 5 Oct 2001 16:01:13 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: [vanagon] LEDs for idiot lghts and temp gauge
Comments: To: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
In-Reply-To:  <f04330104b7e3040b39db@[202.27.183.51]>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 03:25 AM 10/5/2001, Andrew Grebneff wrote:
>LEDs can be run through a rheostat (or electronic equivalent) to vary
>their intensity. I asked an electronics expert, as I plan to change
>my instrument lighting to backlit by several selectable sets of

Just make sure that there is sufficient (permanent) resistance in the
circuit to limit the maximum current to some acceptable value.  Most LEDs
can handle 20 milliamps if the temperature is reasonable.  If you want to
do it right, get ones with known specs and adjust the limiting resistors to
meet the spec.

Side note -- unlike incandescent bulbs, LEDs will light dimly with
extremely small currents.  My oil pressure LED, for example, is a
super-bright poke-your-eye-out clear red LED -- in the dark I can barely
see it glowing from leakage current that I doubt is more than a few microamps.

david


David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"