[Diy_efi] Re: [WB-o2] LED changes brightness

[bcroe at juno.com]

I have been doing a little testing, and I found a problem.  
SOMETIMES my DIY-WB heater circuit became unstable 
and was unable to drive the heater 100%.  Dimming LED.
I fixed it with a .047mfd cap across D5, pins 1 and 3.  These 
are the 2 end pins, easy to tack a cap onto.  Philip, could 
you try this and see if it helps?  The exact value of the cap 
could vary some.  

I also tried my 1 min timer that shorts out R4.  It worked 
well after the above fix.  Dropped the minimum input voltage 
to below 11.7V for me.  The circuit was stable.  Once again, 
Philip could you try the clip lead shorting R4 after a minute, 
again after the above fix?

If all this checks out, I will be asking for someone I can 
FAX the circuit to, who then can post it on a web site for 
the rest of us.  

Bruce Roe

15 Mar 03 "Philip V. Glazatov" <gphilip at umich.edu> writes:
> My U1 is heat sinked well. It is bolted to a huge aluminum plate 
> through a 
> heatpad made of SP900 material. My R4 might be questionable though. 
> I could 
> not find any heat transfer glue anywhere, so I clamped it down to 
> the same 
> plate using the same heatpad material.
> 
> I will do the tests that you suggested and report back. I will also 
> finish 
> my second box this weekend and see if it does the same thing.
> 
> Philip
> 
> At 09:20 PM 3/14/2003, bcroe at juno.com wrote:
> >Sounds like my fix didn't work, at least not for you.  I'd
> >  better do some testing.
> >
> >You should see 1.25V across R4 when you first turn
> >it on.  I am wondering if your U1 is bad, do you have
> >plenty of heat sink?
> >
> >Check the vo;tage between th Alternator output stud
> >and the case.  Connect there (fuse to stud) if you
> >can't get your cig wiring to deliver full voltage.
> >
> >Bruce Roe
> 
> 
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> WB-o2 at diy-efi.org
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> 


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