[sdiy] Quadra phasor clone questions

[Tim Ressel]

Harry,

Yep indeed, it feeds a non-inverting opamp input. Even
if it didn't, I don't like leaving high impedance DC
paths laying around.

--tim

--- harrybissell <harrybissell at prodigy.net> wrote:
> RE: the 10uF....
> 
> you don't need the DC path after the cap... but it
> is common practice
> if that point can be connected to the external world
> or conditionals
> like
> a switch contact.
> 
> The far side of the cap will float to whatever level
> it 'likes'...which
> may not
> be ground. Then if you change the load.. it will
> thump.
> 
> I didn't look at the schematic lately... one other
> variation is if the
> capacitor
> feeds a non-inverting opamp input... it MUST have a
> resistor for the
> bias current
> path (but not for the cap)
> 
> H^) harry
> 
> Tim Ressel wrote:
> 
> > Hey,
> >
> > I've been taking a good look at Juergen Haible's
> > Quadra Phasor clone. I'm a bit confused over the
> input
> > circuit. First there is an attenuator of about 6.5
> to
> > 1, followed by an amp with a gain of 2.6. It seems
> to
> > me this serves to increase the noise in the
> system.
> > After the 1st amp there is AC coupling with a 10uF
> > cap, but there is no DC path to ground after it. I
> > think this will cause clipping for inputs with
> narrow
> > pulses.
> >
> > Any insights?
> >
> > Other than these little puzzles, I am going ahead
> and
> > building one of these.
> >
> > Thanks!
> > --tim
> >
> > __________________________________________________
> > Do you Yahoo!?
> > Yahoo! Mail Plus - Powerful. Affordable. Sign up
> now.
> > http://mailplus.yahoo.com
> 


__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com