Date:         Sat, 26 Aug 2006 13:37:02 -0500
Reply-To:     Larry Alofs <lalofs@RCN.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Larry Alofs <lalofs@RCN.COM>
Subject:      Re: What Ohm value should a dash LED measure?
Comments: To: Jim Felder <felder@KNOLOGY.NET>
Content-Type: text/plain; charset=us-ascii; format=flowed

Jim:
  An LED is a non-linear device.  In other words its apparent resistance
will depend on what voltage the tester applies to it.  Since it is a
diode its "resistance" will also depend on which way the + an - test
leads are connected.  The best approach to checking them is to remove
them completely from the circuit if possible and use a 9V battery with a
resistor in series of about 1000 ohms.  This resistance is high enough
to prevent damage to the LED but still low enough to let you see some
light if it is working.  If you are not sure about which LED lead is pos
or neg, just try it both ways.  If it won't light at all it's bad,
either open or shorted.
HTH,

Larry A.


Jim Felder wrote:

> Mine (I'm measuring LEDs in three consoles) seem to be all over the
> place, varying between 1 and 100, mostly around 30.
>
> The little yellow (resistors?) in the foil circuitry seem to be
> about .6 Ohm.
>
> Thanks,
>
> Jim
>