pid controller circuit

[azeemahmed]

i need a pid controller practicle working circuit for light intensity control.
plz help me out with this.

[Nick Mulder]

wouldn't proportional control be enough ?  or are you introducing drag/delay/error in the system yourself ?

An outline of the sensor and driven system would be helpful for anyone who wishes to help you, are you working in analog or going digital ?

a lamp and LDR/phototransistor ? what are the surrounding conditions/is it isolated ?

[azeemahmed]

thank you for the kind reply.
i am controlling the lamp using TRIAC phase angle control. secondly Integrator with propotional is a must to have a value at the ouput when the error goes to zero. the transducer used is a photovoltiac detector(solar cell).
the controller will control any change in light intensity due to disturbances in the AC voltage supply and disturbances from any other light source. e.g doors and windows, light intensity usually flickers while watching tv due to light from tv. sometime in thunder storms when the windows are banging(open and close), in welding workshops these are all examples of some rapid disturbances, this will require a differentiator as well. this is all that i think maybe u have a better idea.

[Nick Mulder]

the reason i am aware of PID control is through reading up on motor control - perhaps you could look into modifying some of the cct's and systems used in that field ?

the forums at CNCzone.com have heaps of info on that...

[move] :P