Date:         Thu, 7 Jun 2012 14:56:36 -0700
Reply-To:     Steven Johnson <sjohnso2000@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Steven Johnson <sjohnso2000@GMAIL.COM>
Subject:      Re: more mysterious circuitry
In-Reply-To:  <CA+n284Npku-9O_43M7Jz5j9XY8j_kQm+bSjmbpsfNa2FRzCxmA@mail.gmail.com>
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Pretty sure the resistors are current protection and the diode is to
protect the led circuit
from the variable alternator voltage.

Steven J.

91 Westy

On Thu, Jun 7, 2012 at 1:49 PM, pickle vanagon <greenvanagon@gmail.com>wrote:

> Mysterious to me at least... I'm sure to the Beierl's of the word it makes
> perfect sense!
>
> The alternator led circuit has me confused.  (This is shown, for example,
> on 97.74).
>
> It goes from 12 volt power supply, splits into two tracks.  The first track
> goes through a 60 ohm resistor, the second track goes through a 470 ohm
> resistor and then through the alternator led, and then they meet up again
> and go through a diode on their way to the alternator.
>
> (The 60ohm resistor is actually two 1watt 120ohm resistors in parallel).
>
> Why does this need to be like this?
>
> My curiosity stems from the fact that I have two 1 watt 100ohm resistors
> available, and I'm wondering if I can replace those 25yr old 120ohm
> resistors with them, or if I need to leave them be.  I'm also wondering
> what parameters I need to worry about from the standpoint of upgrading that
> LEDto something brighter.
>