Re: Re[4]: LF: Automatic variometer circuit

[Andy Talbot <andy.g4jnt@gmail.com>]

Yes, Indeed

Andy

On 31 October 2015 at 17:00, Chris Wilson <chris@chriswilson.tv> wrote:

Hello Andy,

Saturday, October 31, 2015


Is this what you mean?

http://www.chriswilson.tv/phase-driver.jpg

Thanks.


> Actually, looking again at the circuit again, it is not necessary
> to use an opamp in that position to define the mid rail for the
> comparator reference.    Just two equal; value resistors and
> oneelectrolytic decoupling the junction to ground (Definitely not
> two caps to top and bottom in the original configuration shown ... think about it...)  


> You only need an opamp to define a stiff mid rail voltage where
> there is likely to be any significant current draw.  Or many stages
> need to be referenced to it - such as a multi stage filter.    For
> single stage configurations, just two resistors and a bit of decoupling is enough









--
Best regards,
 Chris                            mailto:chris@chriswilson.tv