ASM-1 oscillators

[gstopp at fibermux.com]

     The LM311 comparator provides the discharge pulse to the FET, so if 
     there were an area of power bus spikes I would first look at the +15 
     supply at this chip. Since the +5 reference for the sawtooth discharge 
     is provided to the LM311 at its (-) input with a +15/20K/10K resistor 
     divider, if the +15 were to dip momentarily then this reference would 
     dip as well, causing possible early reset of the sawtooth. This 
     junction is where the sync input is attached through a 100pf cap, BTW.
     
     However since the VCO's appear to be quite independent of each other 
     this could be considered a moot point.
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: Re: ASM-1 oscillators
Author:  Tom May <ftom at netcom.com> at ccrelayout
Date:    5/8/96 12:30 PM


Joachim Verghese <jocke at netcontrol.fi> asks:
     
>I was wondering, with these fast-reset sawtooth VCOs, are there any 
>hints of VCO interference (interlocking) at all? How does local supply 
>decoupling affect the performance in this context?
     
Correct me if I'm wrong, but it seems the oscillator reset would cause 
a large current spike in a very small loop which does not include the 
power supply, just the capacitor and whatever is discharging it.  The 
current available from the supply is limited by the current source 
controlling the cap's charging current, right?
     
Tom.