Hi, folks, I am, as you will recognize, a n00b to Arduino. I'm interested in using the SousViduino setup to drive a cooling element (like your bitchin' peltier unit) to control a regulated cold bath, analagous to the SouVide setup. Indeed, I want to pair the regulated cold bath with the regulated hot bath to optimize a thermal grill.
In reading through the sketch, it's not clear to me where (or if) it needs to be different for running a cooling element rather than a heating element. I am likely missing something. Does the autotuning allow it to figure out which direction its output moves the system?
Thanks for your advice!
RB
Sous Viduino - using it to control a cold bath?
Moderators: adafruit_support_bill, adafruit
Please be positive and constructive with your questions and comments.
- so_650
- Posts: 5
- Joined: Tue Oct 27, 2015 12:28 am
- Franklin97355
- Posts: 23912
- Joined: Mon Apr 21, 2008 2:33 pm
Re: Sous Viduino - using it to control a cold bath?
The sketch will turn the power on if the temperature is lower than the set point so you would need to modify the code to work the other way. Finding the places where the temperature is checked and an action is taken would be a good start.
- adafruit_support_bill
- Posts: 88096
- Joined: Sat Feb 07, 2009 10:11 am
Re: Sous Viduino - using it to control a cold bath?
The last parameter in the PID constructor specifies whether the PID should operate in DIRECT or REVERSE mode:
http://playground.arduino.cc/Code/PIDLibraryConstructor
The SousViduino uses DIRECT control. Just change DIRECT to REVERSE in the following line:
http://playground.arduino.cc/Code/PIDLibraryConstructor
The SousViduino uses DIRECT control. Just change DIRECT to REVERSE in the following line:
Code: Select all
//Specify the links and initial tuning parameters
PID myPID(&Input, &Output, &Setpoint, Kp, Ki, Kd, DIRECT);
- so_650
- Posts: 5
- Joined: Tue Oct 27, 2015 12:28 am
Re: Sous Viduino - using it to control a cold bath?
Thank you both!
Franklin, I was hoping the sketch would include "remedial thermostat" language, like: "if T(actual) < T(set) then turn the baby on;"
Alas, 'twas not to be found.
support_bill - Many thanks for pointing out that that's in the PID function. I'll give it a try.
Franklin, I was hoping the sketch would include "remedial thermostat" language, like: "if T(actual) < T(set) then turn the baby on;"
Alas, 'twas not to be found.
support_bill - Many thanks for pointing out that that's in the PID function. I'll give it a try.
- adafruit_support_bill
- Posts: 88096
- Joined: Sat Feb 07, 2009 10:11 am
Re: Sous Viduino - using it to control a cold bath?
Code: Select all
"if T(actual) < T(set) then turn the baby on;"
Peltier Devices do not respond well to repeated thermal cycling. Efficiency will suffer and the lifetime of the junction will be short. You should use a relatively fast PWM frequency instead of the TPO output.
Please be positive and constructive with your questions and comments.