Got New 4 Rack Digital Today

[TomG]

Hot Damn BubbaG, where have you been ??? ???

[Arcs_n_Sparks]

Exactly. All these PID questions and the main man has been radio silent ??? :o

Arcs_n_Sparks

[projump]

Hello,
    Thanks for the comments and responses. I will smoke again this coming weekend. Not sure what I will cook yet. I'm also working on a storage cabinet to put on my deck to keep the Bradley in. I'll post a pic when it's done.
   Yeah the total time I cooked the meat was 4 hrs and 15 min. The wife tells me the chichen skin was good and tender.
   What does PID stand for? I know it's electronic and regulates the temp. I don't know if the digital Bradley unit is considered a PID. And yes, I was just wondering about the temp variation range between a digital BS and an original BS equipped with a PID.  projump
   

[West Coast Kansan]

Just re read my post and see where the confusion would be on my PID comment.  I didnt intend to relate a PID to the Bradley Digital. it was intended to compare the digital to accuracy of the PIDs folks here on the forum have rigged up on thier units.  Sorry about the confusion. I dont know all that much about the control in the Bradley Digital but it does not appear to be a proportional at all ... at least from what I can observe from my unit.  It seems to go up past the set point then suddenly decides that is enough ... shuts off and then wakes up again (eventually) as the temp drops past the set point. Seems to be ON or OFF without much of a variation in the duty cycle at all.

The good thing is that it sure seems to behave consistently so is becoming a lot easier to use with some experience. Frankly when I first started looking at Bradley I could not figure out what all the excitement was about relative to temperature of the oven but having seen pictures of some of the slick PID units guys have built and gaining some electric smoker  experience I have come to appreciate it a lot more. I think the PIDs offer another avenue for some fun but being a digital owner I am happy just the way it is... having fun.

[Arcs_n_Sparks]

projump,

Ready for your honorary E.E. degree? PID stands for Proportional, Integral, Derivative. This is a type of control scheme that applies various parameters to the control system. Basically, an error signal is derived from the difference between the setpoint and measured parameter (in this case, temperature). A proportional gain is applied to the error signal and fed to the control system. This will bring the system into alignment, but may have residual error. The integral term will drive the error to zero. The derivative term is used to "anticipate" how changes to the setpoint will affect the final value.

This is all complicated by various timing constants (turning on the Bradley to 100% will take some time to bring up the temperature). Turning off the Bradley at setpoint will result in overshoot, thus the cycling you see. Home heating thermostats applied this technique, but usually have a deadband of a few degrees.

For the purists (those are people that still use vacuum tube amplifiers (which actually have a lot of distortion, but that is another topic), and drink single malt scotch), the goal is minimal swing around setpoint. Which may or may not make any difference depending on what you are smoking.... :D :D :D

Arcin' & Sparkin'

[bubbagump]

Hot Damn BubbaG, where have you been ??? ???

Hi TG,

Olds asked the same question awhile ago. I'm slowly getting back into the swing of things.  :)

http://forum.bradleysmoker.com/index.php?topic=3396.0

Bubbagump

[projump]

 arc-n-sparks,
        Thanks for explaining PID to me, now its clear as mud to me, lol    ???
     You must be an electrical engineer.
                                            projump

[asa]

projump -
good job - those thangs look good enough to eat!