[Diy_efi] SUCCESS! (was Re: LED changes brightness)

[Philip V. Glazatov]

Bruce, you are THE MAN!

I took one of those small yellow 0.1 mfd caps (C8, 9, 13, 14) and connected 
it to D5. First I connected it wrong. I connected it to pin 2 and the pin 
that is closer to the LED. It still worked! The LED stopped blinking and 
started shining constantly and MUCH brighter. Then I reconnected the cap 
correctly to pins 1 and 3 and it still worked just as well. The cap by 
itself solved 99% of the problem!

Then I shorted the R4 and the LED blinded me!!! So I am now typing to you 
blind. :-)

I did some other tests that you asked for. The voltage drop across R4 was 
1.32 V in the beginning. It started slowly dropping to about 1.16 after the 
LED came on. After it settled I checked the voltage across J3 and J4 and it 
was 13.42 V. I went and checked the voltage at the battery (the alternator 
is kinda hard to reach) and it was 14.32 V. Even with that good and healthy 
voltage my LED was still barely glowing and blinking periodically.

So should I now just solder that capacitor across D5? Could that change the 
WB calibration?

I would also like to implement you other fix that eliminates R4 so that I 
am less dependent on voltage. I also need to know what tests to do to make 
sure that I do not have too much or too little current going to the sensor 
heater. But I guess that might never bother me again.

Thank you very much for finding the problem and a solution. You could fax 
me a scheme (708-585-3470) and I will post it for others to see.

Philip


At 12:32 AM 3/18/2003, bcroe at juno.com wrote:
>17 Mar 03 bcroe at juno.com writes:
> > C11 is a 47 mfd polarized cap, not what you want.  I said
> > 0.047 mfd (not polarized).  But any of the 0.1mfd will probably
> > work (C2, 7, 8, 9, 13, etc).  No matter which way it goes.  Or
> > put 2 of them in series to get 0.05 mfd.
> >
> > 16 Mar 03 "Philip V. Glazatov" <gphilip at umich.edu> writes:
> > > Okay, Bruce, I unsoldered the C11 capacitor from my
> > > other controller, which I have not finished yet. Will it work?
> > > I need to know which way to connect it.
> > >
> > > You could fax the circuit to me 708-585-3470. Thank you
> > > for your efforts trying to solve this.
> > >
> > > Philip
> > >
> > > At 06:57 PM 3/16/2003, bcroe at juno.com wrote:
> > > >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


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