I tried the
On Mon, Jul 21, 2014 at 7:02 AM, Attila Kinali <att...@kinali.ch> wrote: > > How about doing it the old analog way? Feed the output of the > PID controller to comparator together with a sawtooth signal. > That will give you a quite nice 0-100% PWM control. > I'm quite sure a similar solution is possible with a NE555 as well. > I tried an analog controller first. It is very hard to implement a tunable PID controller that does PWM without using a bazillion chips. My second controller worked much better and a I wrote, uses only a single 8-pin DIP chip. The AVR uP has more analog inputs and outputs then you need and costs about $1.25 As for the fan startup. What you do is test it and store the minimum fan voltage in a constant and use that as the zero point. So the "P" part of the PID sets the fan voltage to the temperature error times a constant plus the zero point. A better solution is to use a tachometer fan. Then the controller does not set the fan voltage but sets the fan speed. there are still extra pins on the controller and this is one upgrade and the other upgrade is to measure absent air temperature But the simple controller does well enough. I don't see any reason at all to build a PWM controller with a comparator. Multiple sets of that hardware is built into every uP and they cost nearly nothing and come in a single 8 pin DIP. > > Of course, you would need to adjust the PID controller parameters > to accomodate for the new element in the control loop. > > Attila Kinali > > -- > I pity people who can't find laughter or at least some bit of amusement in > the little doings of the day. I believe I could find something ridiculous > even in the saddest moment, if necessary. It has nothing to do with being > superficial. It's a matter of joy in life. > -- Sophie Scholl > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.