[Wbo2] simple warning LED display

[Tommy]

Sorry James, and everyone else, but this is way over my head.  I have a
very basic understanding of electronics.  Basically I know the
difference between a resistor and a capacitor?.but not beyond that to
any certainty.  The 15:1 doesn?t have to be precise, the led can trigger
at stoich ~ 2.5v.  I only want the led to come on at this voltage or
higher.  I shouldn?t be anywhere near stoich at WOT so if the light
comes on, I know there is a problem, ie. Additional injectors failed,
clogged filter, etc. 
 
Operating temp?  Not a clue.  
 
I was figuring this could be done in a simple circuit, but not so sure
anymore.  Atleast simple to me.
 
Thanks again
 
-----Original Message-----
From: James Holland [mailto:J_Holland at btopenworld.com] 
Sent: Sunday, September 18, 2005 12:50 PM
To: Tommy; wbo2 at diy-efi.org
Subject: Re: [Wbo2] simple warning LED display
 
I spoke too soon, I just had a look at the actual numbers. The
difference between stoich and 15:1 is only around 0.025V which is around
1%, that would need a very high degree of accuracy, a precision
reference, a comparator with a pretty good spec (LM139 maybe) and 0.1%
resistors. It might be possible, what sort of operating temperature
range are you aiming for?
----- Original Message ----- 
From: HYPERLINK "mailto:J_Holland at btopenworld.com"James Holland 
To: HYPERLINK "mailto:Crash813 at sbcglobal.net"Tommy ; HYPERLINK
"mailto:wbo2 at diy-efi.org"wbo2 at diy-efi.org 
Sent: Sunday, September 18, 2005 6:02 PM
Subject: Re: [Wbo2] simple warning LED display
 
Consider using a comparator circuit, something like an LM319 would be
OK. 
----- Original Message ----- 
From: HYPERLINK "mailto:Crash813 at sbcglobal.net"Tommy 
To: HYPERLINK "mailto:wbo2 at diy-efi.org"wbo2 at diy-efi.org 
Sent: Sunday, September 18, 2005 3:29 PM
Subject: [Wbo2] simple warning LED display
 
I?ve been on a search to find a very simple LED display for a wideband
unit.  What I want is a simple 1 led warning light that will trigger
when I get a lean voltage.  I don?t want to monitor the range all the
time.   I just want a single led to come on with a AFR of 15 or greater.
A light that when at WOT, I?ll know something is wrong without having
the interior of the car look like a disco club.  If anyone has any
ideas, links, past projects, etc I would be very appreciative.
 
Thanks
Tommy
 
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