> -----Original Message----- > From: andy pugh [mailto:[email protected]] > Sent: October-06-19 9:21 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Spindle Speed Control. > > On Sat, 5 Oct 2019 at 16:17, John Dammeyer <[email protected]> > wrote: > > > That part is perfect. Didn't know there were opto's like that out there > > that could have a VCC of 10V. > > > I mainly selected it for the output driver, which actively discharges the > cap through the resistor when off and charges when on.
Yes but does it discharge to 0V or the is there a semiconductor junction voltage drop involved. With an external pull-down resistor, over time the cap would discharge back through the series resistor and the pull down resistor. Now if the device is a FET with a mill-ohm ON resistance then it's not an issue but if it's a transistor it likely won't reach 0V. The only way I can make the op-amp go below 0.2V is to add a negative supply to the op amp and bias the circuit with -0.2V so that 0% PWM brings the output to 0V. Just didn't want to add the minus supply but I can do that with a ICL7660. Just not sure I have one in my parts bin. > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is designed > for the especial use of mechanical geniuses, daredevils and lunatics." > � George Fitch, Atlanta Constitution Newspaper, 1916 > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
