[Diy_efi] WB02 not passing tests completely

[William Shurvinton]

I noted a similar effect which turned out to be due to a tiny input offset
on the op-amp. In my case the test did nothing as the offset was enough to
keep the integrator pegged at max. using a power supply to provide a
different voltage and everything was fine.

In theory the test should not work as if you had a perfect op-amp there
would be no input differential. But op-amps aren't perfect. The test is
simple and works in 99% of cases so no real worries

NB I used scrounged op-amps from work so likely different manufacturer/batch
from the ones steve supplies.

Bill
----- Original Message -----
From: rr <RRauscher at nni.com>
To: <Diy_efi at diy-efi.org>
Sent: Thursday, May 23, 2002 10:02 PM
Subject: Re: [Diy_efi] WB02 not passing tests completely


> This tests the integral function. This function is what brings
> the feedback loop to zero error (slowly). Your DIY-WB will
> function even with a longer time constant.
>
> Also check R33, C7 and R17. They may have some effect
> on what you are seeing.
>
> If all looks OK, try it out. No damage will be caused with
> the longer time constant.
>
> BobR.
>
>
> rob files wrote:
>
> > Hi BobR,
> >
> > What is the significance of these time specs?  Which components
influence?
> > >From the test procedures and from inspection of the circuit, it appears
to
> > be controlled by C10, R18 and R34.  I have verified the resistors, and
C10
> > is the big ass capacitor, so that one is hard to get wrong.  Maybe I
have
> > short on one of my traces...
> >
> > Still I would like to understand a little better what these tests
validate
> > and what the slow ramp times would mean to the operation of the WB
sesor.
> >
> > Thanks for the help,
> > Rob
> >
> > >From: rr <RRauscher at nni.com>
> > >Reply-To: Diy_efi at diy-efi.org
> > >To: Diy_efi at diy-efi.org
> > >Subject: Re: [Diy_efi] WB02 not passing tests completely
> > >Date: Thu, 23 May 2002 16:27:25 -0400
> > >
> > >That doesn't sound right. If it is truely twice as long I'd look for
> > >a resistor(s)/capacitors(s) that are mis-placed. Remember
> > >that these time factors are +- 10% due to the available components.
> > >
> > >BobR.
> > >
> > >
> > >
> > >rob files wrote:
> > >
> > > > Hi all,
> > > >
> > > > For steps #34 and #42 there are time constants given.  For both
tests,
> > >my
> > > > board takes roughly twice as long as specified.  Is this a problem,
and
> > >if
> > > > so, where should I look?
> > > >
> > > > It passes all other tests with flying colors.
> > > >
> > > > Thanks,
> > > > Rob
> > > >
>
>
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