[sdiy] Ultrasonic VCO question for Ian Fritz (or whoever)

[Magnus Danielson]

From: Ian Fritz <ijfritz at earthlink.net>
Subject: Re: [sdiy] Ultrasonic VCO question for Ian Fritz (or whoever)
Date: Mon, 28 Oct 2002 10:19:57 -0700

> Magnus --

Ian,

I just saw that I made a mistake...

> >The compensation will distort the waveform for higher frequencies but trade
> >from waveform accurateness (which is bad to start with due to the reset slope,
> >I've seen it and it's not excessively nice) for better tracking abilities.
> >What can be a problem is that the compensation leads to a slightly lower AC
> >amplitude and raises the DC offset as the frequency raises and compensation
> >starts to kick in.
> 
> 
> How can you say you say you have "seen it"?  Have you built this circuit? 
> Where did you get the schematic if you don't have the EN issues?
> 
> Why so you think the DC offset would change?  This is a tri oscillator, so 
> I see no reason for the pos and neg half cycles to be affected differently.

Sorry... here I must have speeded in my reading... "tri oscillator" where I was
talking about a "sawtooth oscillator".... so sorry! My misstake.

However, the principle is the same. You get a waveform distorsion in a
triangle-oscillator, but the DC offset compensates out for the triangle case
in relation to the sawtooth case, naturally.

Naturally, this time I pictured a fairly normal triangle core. Could be off by
many kilometers since I don't have access to the schematic in question. Maybe
I should just shut up so others may briliance...

Magnus